explain xkcd - User contributions [en]

Talk:2630: Shuttle Skeleton

2022-06-11T16:08:13Z

108.162.245.215:

Well, I know what "paint job" I'm putting on the pirate shuttle, in my next TTRPG session. 
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 13:12, 8 June 2022 (UTC)

TaxOnomy.

The joke here is about a recent California court case (https://www.cnn.com/2022/06/06/us/california-bees-fish-court-ruling-scn-trnd/index.html) which declared bumblebees to be considered fish under the California Endangered Species Act. The definition of "fish" listed in the act included invertebrates, which is why skeletons are relevant. [[User:Clam|Clam]] ([[User talk:Clam|talk]]) 14:36, 8 June 2022 (UTC)
:I don't know if this comic is related to the bee/fish ruling or not. There have been many earlier works where the skeleton of a fictional person or creature has been shown (the Simpsons, Lego man, etc). [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 17:14, 8 June 2022 (UTC)

Could someone explain why this is a mammal skeleton and not say, something related to a crocodile or a bird? Currently there's only a hint what makes it look like one. Which doesn't say that much to someone who doesn't know mammal skeletons too well. TIA! [[User:Chichak|Chichak]] ([[User talk:Chichak|talk]]) 17:09, 8 June 2022 (UTC)
:That's a good question, since there are lots of skeletal analogues among all the vertebrates. Crocodiles and birds only have 4 toes on their rear legs, so that could be part of it. It may just be an overall resemblance to whales, which we already know are mammals. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 18:06, 8 June 2022 (UTC)
::Well it definitely wouldn't be fish. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 18:36, 8 June 2022 (UTC)
::I'm actually confused about this. Mammals do not have ribs going all the way to the hips. Those look more like reptile ribs. 23:30, 8 June 2022 (UTC)
:::The head of this shuttle looks a lot more like a whale's head, specifically a toothed whale like a sperm whale. The arms are closer to the paddle-like structure of whale arms, but much longer, to be able to form the wings and control surfaces at the back. Having the ribs continue all the way to the pelvis, like a snake, would be an adaptation to give structure to the cargo doors, but that would likely impede their ability to open. Also, I do not know of any mammal that have ribs above the shoulder blades. The clavicles should be there [[User:Nutster|Nutster]] ([[User talk:Nutster|talk]]) 16:28, 9 June 2022 (UTC)
::::Those are extended transverse processes of the cervical ribs, or at least that's how I interpreted them. Note that the transverse processes are evolutionary descendants of what were ribs in an ancestor. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 17:51, 9 June 2022 (UTC)
:::::To me, there's definite impression of a bat skeleton, most notably that the fingers are hugely elongated to become the formers for the wings and the legs/feet are small enough to be nearly useless for anything more than basic gripping.[[Special:Contributions/108.162.245.215|108.162.245.215]] 16:08, 11 June 2022 (UTC)

These "citation needed" tags are getting ridiculous, but I do wonder about whether any space craft had plastic parts. Metal, yes. Carbon fiber, yes. Plastic? I doubt it. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 17:14, 8 June 2022 (UTC)
:They SHOULD be ridiculous, so good job. Regarding the question, I guess space craft may have plastic cup holder for example. The plastic parts are unlikely to be on outside, but inside, why not? In Apollo 13, they were using plastic bags for something at least. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 18:36, 8 June 2022 (UTC)
:: I was just thinking about the skeleton, you're right. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 22:08, 8 June 2022 (UTC)

This comic was unexpectedly terrifying. Not sure what I expected, but it wasn't this.[[Special:Contributions/108.162.246.62|108.162.246.62]] 20:43, 8 June 2022 (UTC)

I was just reading D'Arcy Thompson's "On Growth and Form". (John Tyler Bonner's 1969 abridgement of the 1942 edition.) At the end of the book, Thompson draws skulls on a grid, such as an early ancestor of the horse, Hyracotherium, and then distorts the grid in a uniform way to produce a new sketch that resembles a related species. He then used the same technique to demonstrate that other species were not "missing links" between those two species, because he could not distort the grid to make them fit. [[User:Tanana|Tanana]] ([[User talk:Tanana|talk]]) 02:41, 9 June 2022 (UTC)
:I'd be very wary of someone using a form of personal incredulity to demonstrate something (c.f. the "junkyard+tornado->jumbo jet" 'counter-'argument). I'm not aware of the book, but it sounds like it's anti-evolution, by your telling of it, and picking a case where you can 'find' a simple distortion that works across two examples doesn't then invalidate the intermediate stages for which there's no reason to believe a consistent evolutionary pressure would create similarly smooth transitions at all stages you get to observe. It's observing the end-points of a random-walk and then being surprised at where the walker has managed to visit along the way. The term "missing link" is also outdated (those who use it these days tend to then require additional missing links be found betwixt any now-found 'links' and their neighbours, rather than ever be usefully satisfied) but I suppose might have still been a bit more mainstream back in 1942.
:So sounds like a fun book to read (I like a good cryptozoology/gods-were-aliens book, too!) but I'd be wary about it not having aged well (as I would with bits of the Origin Of Species, though it has held up surpisingly well), and I hope you're also reading it in a suitable frame of mind and not taking it (or passing it on) at face-value. [[Special:Contributions/172.70.162.147|172.70.162.147]] 09:04, 9 June 2022 (UTC)
Yes, the book (On Growth and Form) is certainly dated in places (first edition was in 1917). But I wouldn't characterize his arguments as being completely anti-evolutionary. It's just that he notices many instances where the physical forces on organisms seem to be directing the form of the organisms. He doesn't explain the exact mechanism of change. (At least in the abridged edition.) He's pretty searchable with Google Images. [[User:Tanana|Tanana]] ([[User talk:Tanana|talk]]) 20:36, 9 June 2022 (UTC)
:Maybe search when I can spare time. Sounds a bit Lamarckian, too... ;) [[Special:Contributions/172.70.162.77|172.70.162.77]] 23:04, 9 June 2022 (UTC)
By way of explanation, I think I thought of D'Arcy Thompson because of his strong emphasis on how physics and mechanics (could) contribute to biological forms. Mr. Munroe seems to be playing with some of the same ideas. [[User:Tanana|Tanana]] ([[User talk:Tanana|talk]]) 03:50, 10 June 2022 (UTC)

Well that's horrifying. [[User:TheLonelySandPerson|TheLonelySandPerson]] ([[User talk:TheLonelySandPerson|talk]]) 01:39, 9 June 2022 (UTC)

On a related note, the Apollo Lunar Module was a completely different design early on, but slowly evolved into its familiar crab-like shape through convergent evolution. [[Special:Contributions/172.71.26.59|172.71.26.59]] 03:14, 9 June 2022 (UTC)
:Carcinization strikes again.[[Special:Contributions/172.71.94.73|172.71.94.73]] 07:25, 9 June 2022 (UTC)

What’s up with the “type of fish or shark”? Sharks are a type of fish, the “or shark” doesn’t make sense?
:Presumably Randall was thinking "bony fish". Maybe that was too technical to be funny. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 12:44, 9 June 2022 (UTC)
:((Edit conflict, and I'm really just expanding upon Nit's summary, but having written it now, here you are...)) It's messy, but often sharks are (paraphyletically) kept out of the "fish" category. Similarly to how mammals, amphibians, etc of the ''tetrapoda'' are actually descended from the "fish" superclass (under its classical branch name, of course). Thus to separate from the bony-fish (and possibly other subtrees, across which the common term "fish" might alply), sharks may be deemed not-fish for classification purposes and it is often good practice to do so.
:Common names confuse matters: a dogfish (shark) is very far related from a starfish, at least as much as a seahorse is more fish (very so, in fact!) than equine. [[Special:Contributions/172.70.91.128|172.70.91.128]] 12:54, 9 June 2022 (UTC)
:: If bees can be classified as fish, then so can sharks! But wouldn't be easier to just expand the definition of endangered species to include invertebrates, rather than lumping things clearly where they do not belong? But, hey, what do I know? I am just a scientist, not a lawyer. [[User:Nutster|Nutster]] ([[User talk:Nutster|talk]]) 16:21, 9 June 2022 (UTC)
Just for clarification, a California court has not ruled that bees are a type of fish. They ruled that when a law specifically states "for the purposes of this law, X includes Y," it means that for the purposes of that law X includes Y. [[Special:Contributions/172.71.26.151|172.71.26.151]] 16:58, 9 June 2022 (UTC)
:It's very like the old "Beavers are fish, for the purpose of eating at Lent/etc" from the Catholic church. Except that I presume they ''aren't'' effectively encouraging the eating of bees/fish, in lieu of anything else... [[Special:Contributions/162.158.159.43|162.158.159.43]] 18:53, 9 June 2022 (UTC)
::Yep, Catholics can now eat beaver, capybara, or bees on Friday. But not Space Shuttles.[[Special:Contributions/172.71.22.21|172.71.22.21]] 20:13, 9 June 2022 (UTC)

Hello, I've replaced the CNN video with an NBC archive video because the CNN video is georestricted to US only (You can check restrictions using https://polsy.org.uk/stuff/ytrestrict.cgi, checking https://www.youtube.com/watch?v=AfnvFnzs91s returns a nearly-red map except for the US). - [[Special:Contributions/172.68.253.61|172.68.253.61]] 18:42, 9 June 2022 (UTC)

I've gotta say this is the most confusing skeleton I've seen. It's certainly a vertebrate (spine? check. skull? check), and it's certainly at least a tetrapod (girdles? check. 1 proximal limb bone, two distal limb bones per limbs? check.), and definitely at least a basal reptile. However, it is correct that mammals (modern synapsids) don't have ribs going down to their hips. Additionally, if those holes in the top of the skull are supposed to be the temporal fenestrae, those are the highest-placed temporal fenestrae I've seen on a synapsid. Usually they're much lower (as an example: in a human, our temporal fenestrae are the space under our zygomatic arch - our "cheekbone," though in all fairness humans are actually poor examples of many things in synapsids). Also, the lack of a third phalanx on any of the digits is throwing me for a loop; I'm sure there are mammals that lose some phalanges on all digits, but for the life of me I can't think of one (even a horse has all three phalanges on the one digit they keep). TL;DR: this skeleton looks more like that of a diapsid reptile than a mammal, in my opinion. (My only qualification is that I have a masters in biology, and, for a year or so, I studied under a paleontologist who specialized in the split between diapsids and synapsids) [[Special:Contributions/172.69.248.143|172.69.248.143]] 18:45, 10 June 2022 (UTC)

2619: Crêpe

2022-05-16T18:24:54Z

108.162.245.215:

{{comic
| number = 2619
| date = May 13, 2022
| title = HITLER DOOD
| image = Hitler portrait crop (cropped).jpg
| titletext = WAT NOU?
}}

==Explanation==
{{incomplete|Created by a ÇRÊPË - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
[[File:crêpe.png|thumb|The word "crêpe" in the comic]]
[[Cueball]] has made a {{w|crêpe}}, a thin pancake known for its legendary status in French cuisine, which he proudly announces. However, the {{w|circumflex}} (the accent above the e) is written strangely. Instead of the usual simple angle (^), it looks more like the outline of a flattened arrowhead (⮝). [[Megan]], who can apparently {{tvtropes|PsmithPsyndrome|hear the orthography}} of spoken text, comments on the odd shape with an appropriate pun.

Megan's response, "Weird circumflex but okay" is a play on the recent expression [https://www.urbandictionary.com/define.php?term=Weird%20flex%20but%20ok Weird flex, but ok]. A "flex" is bragging about something. A "weird flex" is used when the speaker acknowledges (perhaps ironically) that the first person is attempting to brag about something, but doesn't recognise the thing as brag-worthy.

Her answer could also be applied to the shape of the crêpe, as circumflex means "bent around".

In some dialects of English (e.g. British English), and in the original French pronunciation, "crêpe" is said so that the ê is pronounced as in "get", i.e. "cr-eh-p", but American English speakers pronounce it like an "A", i.e. "cr-ay-p".

The title text continues the wordplay by saying that "A medicine that makes you put two dots over your letters more often is a diäretic".

The word diäretic is a pun on {{w|diuretic}} (a substance promoting increased urine production), {{w|Diaeresis (diacritic)|diaeresis}} (a symbol in the form of two dots placed above a vowel, as the ä in the made up word diäretic; the adjective form of diaeresis can be spelled "[https://www.thefreedictionary.com/Diaresis dieretic]") and {{w|diacritic}} (a glyph added to a letter to distinguish its sound from the normal version, what both the circumflex and the diaeresis are). See also the comic [[1647: Diacritics]] about the use of these. Taking a diäretic medicine would supposedly cause you to use diaeresis (also known as umlaut) över möre lëtters thän wöuld üsuallÿ bë thë cäse.

Diacritics are rarely used in English, potentially because of the diverse set of origin languages it developed from, or the wide variation of pronunciations within a same nation, but are a common feature of other languages. In English, they are normally only seen in specific loanwords (such as crêpe) or used for emphasis or decoration (for example the {{w|metal umlaut}} seen in rock bands like {{w|Motörhead}}, {{w|Mötley Crüe}}, {{w|Queensrÿche}}, or {{w|Spın̈al Tap}}). The exception to this is the diaresis, which when it is used at all, is placed over the second vowel in a double-vowel word to indicate a morphological break between them as opposed to a dipthong, e.g. naïve or coöperation. The diaresis is optional, and, especially with words beginning with the co- prefix (e.g. cooperation, coevolution, or coincidence), rarely used. The New Yorker magazine is a famous outlier, advising consistent use of the diaresis in [https://www.newyorker.com/culture/culture-desk/the-curse-of-the-diaeresis its style guide].

==Transcript==
:[Cueball is holding a plate up in both hand, showing Megan the crepe lying on the plate. His word for crêpe has a different diacritic over the "e" than the normal circumflex (^). Instead it looks more like an open arrow head.]
:Cueball: Check out this crêpe I made!
:Megan: Weird circumflex, but okay.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Language]]
[[Category:Puns]]
[[Category:Food]]

1217: Cells

2022-05-04T01:00:14Z

108.162.245.215: undid vandalism

{{comic
| number = 1217
| date = May 27, 2013
| title = Cells
| image = cells.png
| titletext = Now, if it selectively kills cancer cells in a petri dish, you can be sure it's at least a great breakthrough for everyone suffering from petri dish cancer.
}}

==Explanation==
{{w|Cancer}} is one of the most feared group of illnesses due to high mortality and a topic visited by Randall in [[:Category:Cancer|past comics]].

Whenever a study finds a hint of a cure, it is hyped up in media as major breakthrough. However, because research is done in a laboratory using cultivated cancer cell assays in petri dishes or well plates, it typically does not take interactions with other parts of a body into consideration, which is ultimately necessary for a patient to survive treatment without harmful side-effects. In order for a cancer treatment to be viable, it would have to primarily target only cancer cells; not healthy ones. Added to this is the issue that major cancer in the body quickly evolves resistance to most treatments, most treatments end up either unused or used as just one in a cocktail of cancer fighting drugs.

Here, [[Randall]] reminds us that there's no need to get excited upon hearing about a drug that kills cancer cells because it may very well harm healthy cells as well, just as a bullet fired from a handgun would. Alternatively, one could interpret the message that, since something as mundane as a handgun is capable of destroying cancer cells, it really is not too impressive for a drug to make that claim.

The title text suggests that even if a drug did only kill cancer cells while leaving healthy cells alone, the human body still has many other complex processes that may render a drug that works in a petri dish insufficient. For instance, a drug that kills cancer cells in a petri dish may not be able to get at cancer cells deep within a human body. It is a long way from the laboratory to the pharmacy.

A more humorous interpretation of the title text is that it will only kill cancer cells if they are in petri dishes, and not anywhere else. The naming convention here is similar to "lung cancer", breast cancer", etc., but of course, petri dishes are not normally a part of human organism{{Citation needed}}. Less probably, it might be about cancer cells that originated from, but are not necessarily located within, petri dishes, making the scenario even more oddly specific.

==Transcript==
:[Caption above the panel:]
:When you see a claim that a common drug or vitamin "kills cancer cells in a petri dish,"
:Keep in mind:

:[Cueball in a lab coat stands on a chair next to a desk, pointing a gun at a petri dish. There is a microscope on the desk.]

:[Caption below the panel:]
:So does a handgun.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Biology]]
[[Category:Cancer]]

834: Wikileaks

2022-05-04T00:59:49Z

108.162.245.215: undid vandalism

{{comic
| number = 834
| date = December 15, 2010
| title = Wikileaks
| image = wikileaks.png
| titletext = STUDENTS ARE CALLING PRESIDENT JOHNSON EN MASSE TO PROTEST THE BOMBING AND IT'S JAMMED THE WHITE HOUSE SWITCHBOARD. COULD THEY COLLAPSE OUR CRITICAL PHONE SYSTEMS? HAS THE FIRST TELEPHONE WAR BEGUN? STAY TUNED FOR MORE ON THIS DANGEROUS NEW TECHNOLOGY.
}}
[[File:Anonymous_emblem.svg|thumb|upright=1.5| Anonymous' emblem. (from Wikimedia Commons)]]
==Explanation==
This comic references {{w|WikiLeaks}}, a site to which classified data can be sent for publication, while nobody would know who leaked the data. Many people dislike WikiLeaks, but proponents claim that, since government is supposed to work for the people, all government information should be available to anyone who wants to see it. WikiLeaks' actions are illegal in most countries, and the people maintaining WikiLeaks stay anonymous, with the notable exception of {{w|Julian Assange}}, the spokesperson. Among the supporters of Wikileaks are the 4chan-based activism/hacker group {{w|Anonymous (group)|Anonymous}}, who, for the week or so prior to this comic's release, used DDoS attacks to take down servers for companies that aided the governments of the world in taking down Wikileaks and its CEO, Julian Assange. Amazon, PayPal and MasterCard were all targets of Anonymous. The claim 'We are legion' is a reference to Mark chapter 5 in the Bible, in which Jesus throws out a group of demons that call themselves Legion, [http://www.biblegateway.com/passage/?search=Mark%205:1-10&version=NIV "for we are many."]

The comic imagines an ironic scenario in which WikiLeaks, the organization Anonymous fought to protect, stays true to their mission of releasing secrets to the public, and publishes the personal information of Anonymous members. The joke in the comic notes a contradiction in Anonymous's position, relying on strict secrecy of its members' private information while supporting an anti-secrecy organization like WikiLeaks. This may be a reference to an incident in 2009 when WikiLeaks [http://www.wired.co.uk/news/archive/2009-02/18/wikileaks-forced-to-leak-own-secret-info published a leaked list] of some of their anonymous donors, following their then-policy of complete impartiality regarding leaks.

In theory, Anonymous consists of everyone who takes steps to remain anonymous, not merely the hackers and criminals. In practice, Julian would merely have to post a list of Wikileaks contributors.

The title text appears to be a news wire from during the {{w|Vietnam War}} when {{w|Lyndon B. Johnson}} was President in the United States. The students were calling to protest the War, in what xkcd implicates as the first {{w|DDoS}} attack. A DDoS attack is a Distributed Denial of Service attack, one of Anonymous' favorite tactics, in which the attackers send vast quantities of traffic from many different points to take down a web server, or, in the case of the title text, a phone network. Taken as a whole, the title text satirizes news reports in which a DDoS attack is confused with an actual hack, as only in the latter does the attacker gain (partial) access to the system itself.

==Transcript==
:[The logo of Anonymous (but without the question mark), a black formal suit with no head, is talking.]
:Anonymous: We are Anonymous. We are legion. We are no one and everyone.
:Anonymous: And we are here to fight for WikiLeaks.

:[The panel is presented as the front page of WikiLeaks, in a browser.]
:<big>New Leak:</big>
:Names, addresses, IPs, and phone numbers of everyone in Anonymous.
:Download Now

:Anonymous: ...Dammit, Julian.

{{comic discussion}}
[[Category:Internet]]

920: YouTube Parties

2022-05-04T00:59:21Z

108.162.245.215: undid vandalism

{{comic
| number = 920
| date = July 4, 2011
| title = YouTube Parties
| image = youtube_parties.png
| titletext = This reminds me of that video where... no? How have you not seen that? Oh man, let me find it. No, it's ok, we can go back to your video later.
}}

==Explanation==
A {{w|YouTube}} party is when a group of people show each other YouTube videos. The problem with YouTube parties is that no one pays attention to the video that's playing; instead, each person is thinking of the video that they personally want to play next.

You can see analogous behavior at any get-together where couples (parents) are telling stories about their kids. Nobody cares about anybody else's kid; they are just waiting (not even listening) until they get the chance to talk about their own offspring.

The joke seems to be that everybody is doing this, but it is unclear whether they realize it. They each seem to be under the delusion that the others will be fascinated by "their" video (or child's accomplishments), even though the evidence strongly suggests otherwise. Possibly they don't care about that either; they just want an audience, even an unwilling one.

This may be defensible where kids are involved, because the parents could reasonably feel that the accomplishments of their children reflect well on themselves. However, the people in the YouTube party didn't create the videos, they just found them. Which makes their behavior (or perhaps YouTube parties in general) even more inane and pointless.

The title text reiterates this point. The speaker is reminded of another video that is so superior to the one currently playing that we should find it and watch it immediately. We can always go back to the current video later (if anybody still remembers, that is; and according to the comic above no one will ''want'' to remember it).

==Transcript==
:[Cueball and a group consisting of three Cueballs and one Ponytail are standing in a dark room around a table. The group and Cueball are illuminated by a laptop on the table.]
:[Caption above the panel:]
:The problem with YouTube parties:
:Cueball (thinking): This video is blowing their ''MINDS.''
:Group (thinking): Oh man, I know what video we should watch once this is over.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:YouTube]]
[[Category:Multiple Cueballs]]

1889: xkcd Phone 6

2022-05-04T00:59:04Z

108.162.245.215: undid vandalism

{{comic
| number = 1889
| date = September 13, 2017
| title = xkcd Phone 6
| image = xkcd_phone_6.png
| titletext = We understand your privacy concerns; be assured that our phones will never store or transmit images of your face.
}}

==Explanation==
This is the sixth entry in the ongoing [[:Category:xkcd Phones|xkcd Phone series]], and once again, the comic plays with many standard tech buzzwords, and horribly misuses all of them, to create a phone that sounds impressive but self-evidently isn't to even the most ignorant customer. The previous comic in the series [[1809: xkcd Phone 5 ]] was released 7 months before this one and the next [[2000: xkcd Phone 2000]] was released 8 and a half months later.

This comic was released the day after Apple announced their new {{w|iPhone 8}} and the higher-end {{w|iPhone X}} (pronounced iPhone 10) with facial recognition features.

===List of features (clockwise from center/top)===

; Front camera (centered for eye contact during video chat)
: A front camera has become a common feature of smartphones. The camera lens is located on the same side of the phone's case as the main screen, making it possible to capture the image of the user's face looking at the screen and display the interlocutor's face on the screen simultaneously, enabling video chat. However, as the camera is usually located above the screen, when the user looks at the displayed image of the other person they direct their eyes at the center of the screen and not at the camera's lens. This makes it appear on the other end of the chat as if the person talking was looking down and not making eye-contact, which can be an uncomfortable situation for many people. For this reason, professionals involved in movie or TV-making, like actors or reporters, are trained to look straight into the camera's lens while talking, which creates impression of looking straight at the viewer's face. During a video chat, however, looking into the lens of an above-screen camera does not allow one to see the interlocutor's face clearly because it is then in the peripheral field of vision.

: To solve this conundrum, Randall proposes locating the camera lens right in the middle of the screen. The user looking at the the other person's face on the screen would then also be looking at the lens, creating an impression on the other end of the chat that they are looking straight at the other person. This is absurd, since the lens would then take place of some of the center pixels of the screen, which would probably mean that it could not display the center part of the captured image of the other person's face. This could include features such as eyes and/or lips, which play an important part in non-verbal communication. Locating the camera lens in this way would probably also interfere with the touch-screen function. It would probably make other applications on the phone difficult to use, since virtually no user interface is designed to accommodate a blind spot in the center.

: The idea of having the camera in the middle of the screen is only currently absurd, however, as advances in technology may eventually enable such a feature to work without disturbing the appearance or function of the phone's display, unlike the visual disturbance clearly indicated in the comic. For instance, previous technological advancements have improved the functionality of the display, starting with adding touch sensing. The touch sensitive hardware of the phone is located in a thin layer above the hardware, that generates the image for the display, and capacitive touch sensing technology is less obtrusive than previous resistive sensing. While it has yet to be released to market, certain manufacturers are aiming to place a phone's fingerprint reader underneath the screen, for seamless functionality. Although it may be difficult at this point, figuring out a way to have a camera capture images through the array of pixels on the screen is not completely beyond imagination.

; Full-width rear camera
: Historically, there has been an 'arms race' among phone manufacturers to increase the 'size' of the rear camera, in terms of the number of pixels they can capture. This is not typically accompanied by equivalent increases in physical size, though. Phone cameras tend to have lenses which are quite small, and round or square -- measuring the same in width as in height. On this phone, the 'full-width' lens appears to be a long, thin strip, like an oval or rectangle shape. This could allow the camera to gather a lot more light, potentially working in low light situations. However the lens would be more vulnerable to damage and dirt. Unless a very large sensor was used, focusing the image could be a problem, since cell phones are typically not very deep.

; CDC partnership - phone automatically administers seasonal flu vaccine to cheek every year
: U.S. {{w|Centers for Disease Control and Prevention}} is a government agency tasked with addressing public health concerns, such as infectious diseases, including seasonal flu. A common way of limiting the spread of an infectious disease is {{w|Vaccine|vaccination}}, which most often involves administering a specially prepared vaccine via an {{w|intramuscular injection}}, though researchers have investigated other delivery systems, including aerosol, or microneedle injection. Uptake of vaccination is often poor, and many governments routinely use various different campaigns and techniques to try to encourage more people to get themselves vaccinated.

: This feature implies that the phone would automatically perform some form of injection once a year, administering a vaccine via a small aperture while the user is holding the phone to their cheek during a call. However, the placement of this component is dubious, as it would line up with the user's ear, rather than their cheek, during a phone call. It may be designed to detect the fraction of a second during which your cheek would be in the appropriate position (perhaps after a phone call, as you may be dropping the phone from your ear), and administer it at that moment; this would conveniently prevent disturbances to a majority of conversations.

: A further absurdity to this feature is that the vaccine is different every year, in order to account for various mutations causing different, and typically new, strains of the virus, which is the reason it has to be administered yearly. The CDC bases the combination of strains on a best-guess of what will be the most significant strains in circulation over the upcoming year, so in order to have the current year's vaccine, the user would have to physically load the new version into the phone for later administration, or there would have to be a mechanism to synthesize the concoction on-board the phone, and an associated logistics framework and digital standards for OTA delivery of specifications for the year's vaccine.

; 12-function
: Most smartphones can be used for more than twelve different things{{Citation needed}}. However, this may refer to the twelve basic functions of algebra (identity, squaring, cubing, square root, logarithm, exponential, reciprocal, sine, cosine, greatest integer, absolute value, and logistic), or the twelve function keys on a modern keyboard (more than the ten on the original IBM PC keyboard). Alternatively, it may be a reference to calculators: basic models are sometimes referred to as four function calculators (addition, subtraction, multiplication and division), and complex scientific calculators may advertise 250 or more functions.

; Dishwasher safe
: Waterproofing has become a much-pushed feature of many recent smartphones, with manufacturers competing on the claimed resilience of their models. A phone that was truly dishwasher safe would be ahead in this race, as it would have to be able to withstand high-pressure jets of water, high temperatures, and caustic effects of detergent over significant periods. This is often listed as a selling point of items used for preparing, serving, or storing food, such as plastic containers or crockery, which a normal person might want to clean using a dishwasher, but it seems excessive for phones, which are rarely cleaned with anything more than a quick wipe, and most people would not intentionally attempt to clean in a dishwasher.

; GPS transmitter
: Many smartphones have a receiver for the {{w|Global Positioning System}}, which allows a phone to compute its position based on signals from the constellation(s) of GPS satellites. However, a device with a "GPS transmitter" would broadcast signals that would interfere with the GPS receivers of all devices nearby. This might be used in some form of differential GPS, broadcasting signals from a known location to allow more precise determination of other locations, or such a system might be used to confuse or control devices, such as drones, which navigate using GPS.

; 3-G acceleration
: This is a mixture of three unrelated concepts with similar names. In computer graphics, "{{w|Graphics processing unit|3-D acceleration}}" refers to GPU hardware that speeds up handling of three-dimensional data, such as shapes rotating in space. In physics, "3 Gs of acceleration" refers to speed increasing at a rate of 3 times the acceleration of Earth's gravity, or approximately 30 m/s². In cellular networks, {{w|3G}} refers to a standard for data communication. GPUs, accelerometers, and compatibility with 3G networks are all normal features of modern smartphones. "3-G acceleration", however, is not a real term, and doesn't describe any meaningful feature of a phone. It appears to suggest that either the phone is capable of self-propelling with 3 Gs of acceleration, which doesn't seem particularly useful, or, perhaps more feasibly, that it has some way of increasing the data transfer rate over a 3G connection.

; Portable, solar-heated
: Portability is pretty much the entire point of using a ''mobile'' phone, so advertising portability is rather redundant. Solar ''power'' charging could be a very useful feature on a phone, but solar ''heating'' usually applies to plumbing, where a water tank is heated by the sun and used to supply hot water to taps. Technically, as the sun heats up everything it shines on, the phone is in fact solar heated. However, since avoiding overheating is a particular challenge in smartphone design, deliberately capturing solar energy simply in order to heat the device would seem rather counter-productive.

; Pore-cleaning strip
: Pore-cleaning strips are sticky strips designed to be applied to the skin and then pulled away to remove dirt and oils from the pores, with the intention of reducing spots and improving the complexion. The location shown for this feature would be inconvenient and irritating, as it would come into contact with the face every time the phone was held to the ear to make a call; something sticky on that location would be very annoying for clean-shaven people and extremely painful for anyone with facial hair. It would probably also result in that strip of the screen becoming obscured by an accumulation of facial gunk. Pore strips have been mentioned before in [[777: Pore Strips]].

: This may act as a sensor for the ''Shroud of Turin-style facial transfer unlock'', whereby the phone would collect the dirt, oils, and microflora from the user's face when it is pressed against the phone, and use it to verify their identity.

; Maximum strength
: Medicines are often sold as "Maximum strength", usually indicating that they contain the highest dose of active ingredients allowed by law, or allowed without a prescription. For phones, there are sometimes "hardened" or "ruggedized" versions, which are designed to survive harsher environmental conditions, such as surviving drops and collisions, excessive water, dust, etc. ''Maximum strength'' here could indicate such a "ruggedized" phone, though this would be hard to achieve with a screen that extended past the edges.

; Never needs sharpening
: Phones do not need to be sharpened in the first place{{Citation needed}}. This is a feature more likely to be found in a knife advertisement -- the slogan is infamous for hawking knives that ''cannot'' easily be sharpened, like a serrated blade -- or a mechanical pencil. Since the screen goes past the edge, it might be sharp enough to cut through things, much like a knife, though the phone would be unsafe to carry and handle if that were the case{{Citation needed}}.

Might also refer to sharpening the camera, which usually means adjusting the lens till an object is in focus. Most phones have autofocus and rarely need to be manually sharpened.

; Can survive up to 30 minutes out of water
: This is a play on the common IP-rating of water resistance, which is typically rated for submersion to a rated depth for 30 minutes. A phone which could only be used or carried for 30 minutes before it needed to be immersed in water would be rather inconvenient, although the phone short circuiting would likely not be an issue, as the phone is "dishwasher safe."

: Alternatively, either this phone's target market could be whales, dolphins, or other marine life, such as octopodes, or the feature could be optional. While such a feature would prove to be extremely useful for aquatic customers, the "solar-heated" feature would undoubtedly be inhibited significantly as water depths increased.

; Exclusive Audubon Society app identifies birds and lets you control their flight
: The {{w|National Audubon Society}} is a non-profit organization dedicated to the conservation of nature, and mainly of birds, which also organizes open {{w|birdwatching}} events. There are apps that attempt to identify bird species, for example, from a [https://play.google.com/store/apps/details?id=com.labs.merlinbirdid.app&hl=en_GB photo] or [https://play.google.com/store/apps/details?id=com.isoperla.birdsongid&hl=en_GB audio recording] of a bird made by the smartphone itself, though the Audubon Society's [https://play.google.com/store/apps/details?id=com.audubon.mobile.android&hl=en_GB own app] does not offer anything this interactive. An app allowing you to control the bird's flight would be way cooler and might work using the built-in GPS transmitter, confusing their navigation systems. However birds do not use GPS to navigate{{Citation needed}}, and it would fly in the face of the Audubon Society's core activity. This is a reference to {{w|Unmanned_aerial_vehicle|drones}} (which could be thought of as artificial "birds") which are often controlled by a smartphone app. This may also be a reference to [[1425: Tasks]], in which an app that can recognize if a bird is on camera is proposed.

; Extra screen
:Some phones advertise an additional display or display mode, often giving access to basic information, such as battery level and notifications without needing to activate the main screen function. Typically, this would be a low-power mode of operation of the normal screen, or else a form of display on another surface of the phone, such as the side or rear. Here, it seems to be an oddly shaped rectangular extension on the bottom of the main screen. This may have been added to make up for the loss of screen estate due to the center camera.

; Wireless charging port
:A port for {{w|Inductive_charging|wireless charging}} is an oxymoron, since wireless charging has no wires and thus has no need for a port, unless it is required for fuel for a fuel cell (see clean coal, below). This may be a jab at Apple's removal of the headphone port from their previous phones.

; Safe for ages 6-8 months, 10 months, 18 months-3 years, and 12 years and older
:Usually an item is deemed safe for a particular age or older, or (in the case of toys) is recommended for a particular age range. This is unusual in that it's a hodge-podge of age ranges with no apparent reason why some ages are safe and others are not. It may be a parody of drug commercials that list several age ranges for which the drug had to be separately approved.

; Screen goes past the edge
:A parody of the trend of "edge to edge" displays in recent generations of smartphones, or phones whose screens curve partway around the edge of the phone. In this case the screen is wide enough that it ''could'' curve partway around the edge, except the spillover does not actually form to the curves, resulting in a screen that is wider than the body of the phone. If the spillover is rigid, this would make the phone rather uncomfortable to hold, and the spillover is at risk of chipping off.

; High thread count CPU
:A {{w|Thread_(computing)|CPU thread}} is a task the CPU performs. Several threads may share memory, making them a process. Threads are meant to run in parallel and the operating system distributes the workload on the available hardware execution units. These execution units are sometimes called hardware threads, especially when there is more than one per processing unit (or core). For example, the Intel Core i7 7700 is considered a 4-core, 8-thread CPU. The vague "high thread count" statement could make sense in this context, however, it is most likely a joke about bedding, where it is an actual selling point; the thread count of a textile signifies the density of fibres in the material, and a high thread count is an indicator of a high quality fabric.

; Shroud of Turin-style facial transfer unlock
:The {{w|Shroud of Turin}} contains an image of the body and face of a man, originally believed to be {{w|Jesus Christ}}, before the Shroud was found to be 1200 years too young. Some theories suggest the image was created by interaction with or transfer from the body that was wrapped in the shroud. Presumably, to unlock this phone, the user would have to physically {{w|facepalm|press their face}} against the phone, the way the Shroud-Man's image was allegedly transferred to the shroud. This is probably a reference to the iPhone X's FaceID unlock, which uses a ''photograph'' of your face, augmented with spatial information, to unlock itself, and which had attracted [https://www.wired.com/story/iphone-x-faceid-security/ significant criticism] immediately before this comic came out.

; Fonts developed by NASA
: This may be a reference to many advertisements that claim that their product uses technology developed by NASA in an attempt to make it seem more impressive. NASA technology does often tend to be quite strong and advanced, as they claim at their [https://spinoff.nasa.gov/ spin off] website. Between 1975 and 1992 NASA used the {{w|NASA insignia|"worm" logotype}} in its insignia; it was a special font that omitted the horizontal bar in the capitalized letter A. However, it would not be particularly impressive to use this, since fonts have very little to do with NASA's core operations{{Citation needed}}, and it potentially implies that it would not support many other common, and perhaps more readable, fonts.

: This may also be riffing on the {{w|Writing_in_space|urban legend}} that NASA invested vast amounts of research in developing a pen that could write in space, rather than just using a pencil.

; Includes applicator
: This is found on the packaging for many products, such as tampons, cosmetics, and paints. An applicator for a phone would be absurd, since the phone cannot be applied, spread, inserted, or attached to something else. However, this may be referring back to the aforementioned yearly vaccine.

; Burns clean coal
: Clean coal is coal that is burned so that it does not give off as much soot, sulphur dioxide, nitrogen oxides, mercury, or other pollutants as "normal" coal, or methods of burning coal that give off relatively less pollutants. This may be advertised by energy companies trying to appear to be using clean energy, due to pollution concerns. Coal burning power plants are usually quite large, so a traditional coal fired thermal-electric plant in a cell phone would be absurd. {{w|Fuel cell|fuel cells}}, which produce electricity by oxidizing some fuel, can be small enough to fit in a cell phone, but they do not typically burn coal. The cordless charging port might be a receptacle for refueling the phone, using liquid or a fuel cartridge.

; Pre-seasoned
:Pre-seasoned typically refers to cast iron cookware which is ready to use out of the box, as opposed to needing to season it with oil and heat. It can also refer to packaged meats which are ready to cook without needing to be seasoned with herbs and spices, or timber that has been dried and is ready for use. A more technical definition of 'seasoning' means operating devices, usually calibrated standards or battery cells, for a while in the factory, to make sure the device meets constant performance requirements without deviating or diminshing too much. In this sense it could apply to the battery of the phone.

; Broad-spectrum SPF 30
:The xkcd phone somehow gives a {{w|sunscreen|sun protection factor}} (SPF) 30 level of protection from sunlight, meaning that it blocks all but 1/30 of skin-burning UVB radiation from sunlight, though it is not clear whether it is the user or the phone itself which is protected. Phones do not typically require protection from sunlight{{Citation needed}}. On the other hand, if, when placed between the user and the sun, the phone allows >3% of the radiation through, this would be remarkably more translucent, and therefore less effective, than most phones (which allow much less than 1% of UVB, or any other visible or near-visible wavelength, through). It would also be an inefficient method of protection, since it would only be able to protect a relatively small patch of skin.

; College-ruled
:College-ruled is a style of notebook paper having narrower than normal lines, in order to fit more text per page. That the phone is college-ruled suggests that there are lines permanently displayed on the screen, which could obscure any images on the screen, and make any text that doesn't line up with the lines hard to read. Defective screens can show similar patterns; for example, the iPhone 6 "touch disease" causes regularly spaced vertical lines to appear on top of the screen. Here, it is possible that the manufacturer is trying to pass off screen defects as features.

; Sterile packaging
:Useful for medical supplies, less so in a phone. There are numerous studies and resulting 'news' articles looking at the number of bacteria, fecal samples, and so forth, that can be found on the typical phone, typically with a sensationalist take on how you will be 'shocked' to discover this. However, sterile packaging would do little to counter this, since most of this contamination is accumulated after the user removes the phone from the packaging and begins using it.

; Radium backlight
:The discovery of the radioactive element radium sparked a brief fad in which manufacturers of consumer products began coating them with a paint containing radium and a radioluminescent substance, such as zinc sulfide, which converted the radiation from the radium into visible light. In particular, some clock and watch makers painted the faces or hands of their timepieces, allowing the time to be read at night without an external power source for the light. However, it was eventually realized that regular exposure to radium could result in radiation poisoning, particularly for the workers assembling and painting the products. A radium-based backlight would therefore be both potentially dangerous (especially for an object carried on one's person much of the time) but also largely useless, as the radioluminescent light is rather dim compared to conventional phone back lights.

; 4K pixels (50×80)
:"4K" typically denotes a screen with a width of ~4000 pixels, such as 4K TVs, which have 3840×2160 pixels, or about 8.3 million pixels total. That would be an outstanding resolution for a cell phone. Here, however, the "fine print" in parentheses clarifies that 4000 is actually the total number of pixels, not the width, which would be remarkably low resolution for a smart phone. As a comparison, the old Commodore VIC-20, with a resolution of 176 × 184, would have over 8 times the pixels of this phone. It is more comparable to the screen resolution of the sturdy Nokia 3310, which boasted a total of 4032 pixels, positioned 84 × 48.

===Version===
In the caption below the phone [[Randall]] presents many different version numbers:
*The number 6 is in correct order of all the xkcd phones
*The {{w|Roman numerals|Roman numeral}} VIII refers to the newly announced {{w|iPhone 8}} and jokes about the Roman numeral X below
*Version number 10 is the current version of Microsoft Windows
*The {{w|iPhone X}} was announced together with the iPhone 8 by Apple on September 12, 2017, a day before this comic was released. Apple clarified that X is meant to be read as the Roman numeral for 10, so for additional absurdity two xkcd phones share the same number, using different numerals
*The number 26 refers to the number of letters in the English alphabet
*In the year 1876 {{w|Alexander Graham Bell}} received the U.S. Patent No. 174465 for the {{w|invention of the telephone}}, but there is still a {{w|Elisha Gray and Alexander Bell telephone controversy|controversy}} whether {{w|Elisha Gray}} was the first to present a working telephone.

The "nonconsecutive version number war" referenced below the version names refers to several recent phones, and possibly operating systems, released consecutively with nonconsecutive version numbers, including:
*The iPhone X (or Ten) which will be released shortly after the iPhone 8
*The Samsung Galaxy Note 7 was released after the Note 5
*The Oneplus 5 was released after the OnePlus 3T
*The ZTE Axon 7 was released after the original Axon, skipping numbers 2-6.
*Microsoft Windows has a long history of non-consecutive version numbers/names, with the most well-known releases being (in order) {{w|Windows 3.1|3.1}}, {{w|Windows NT|NT}}, {{w|Windows 95|95}}, {{w|Windows 98|98}}, {{w|Windows 2000|2000}}, {{w|Windows Me|Me}}, {{w|Windows XP|XP}}, {{w|Windows Vista|Vista}}, {{w|Windows 7|7}}, {{w|Windows 8|8}}, and {{w|Windows 10|10}}.

Randall's ludicrous naming scheme aims to 'defeat' all of these by eclipsing them. By counting parallel version numbers xkcd defeated Apple 6:2.

The symbols at the end are ™ for trademark, ® for registered trademark, and © for copyright. The degree symbol ° after the letter C could be a play with degree Celsius. The use of all four symbols after the phrase is ridiculous, as ™ and ® indicate trademarks with opposite registration statuses, slogans can't be copyrighted, and the degree symbol usually has no meaning when applied to text.

In the title text Randall recognises privacy concerns about the facial recognition feature. A picture of a face will only be used for facial recognition, but never stored on the device nor transmitted to the internet. A ''small'' side effect may be that the famous selfie pictures aren't possible anymore, as well as video calls. Ironic, considering that the reason the camera is in the middle is to allow easier video calls.

==Transcript==
:[A smartphone is shown, the screen is slightly wider than the case, in the middle is a photo lens, and at the right bottom a small extra part is added to the screen.]
:[On top a bracket ranges nearly over the entire width of the case. The text reads:]
:Full-width rear camera
:[The label at the photo lens is:]
:Front camera (centered for eye contact during video chat)
:[The label on the extra part says:]
:Extra screen
:[At the bottom below the case a label reads:]
:Wireless charging port

:[The labels left to the phone are:]
:4k pixels (50x80)
:Radium backlight
:Sterile packaging
:College-ruled
:Broad spectrum SPF 30
:Pre-seasoned
:Burns clean coal
:Includes applicator
:Fonts developed by NASA
:Shroud of turn-style facial transfer unlock
:High thread count CPU
:Screen goes past the edge
:Safe for ages 6-8 months, 10 months, 18 months-3 years, and 12 years and older

:[The labels right to the phone are:]
:CDC partnership: Phone automatically administers seasonal flu vaccine to cheek every year
:12-function
:Dishwasher safe
:GPS transmitter
:3-G acceleration
:Portable, solar-heated
:Pore-cleaning strip
:Maximum strength
:Never needs sharpening
:Can survive up to 30 minutes out of water
:Exclusive Audubon Society app identifies birds and lets you control their flight

:[Text below the phone:]
:Introducing
:'''The xkcd Phone 6, VIII, 10, X, 26, and 1876'''
:''We didn't start this nonconsecutive version number war, but we will not lose it.''™®©°

{{comic discussion}}

[[Category:xkcd Phones]]
[[Category:Comics sharing name|xkcd Phones]]

1732: Earth Temperature Timeline

2022-05-04T00:58:48Z

108.162.245.215: undid vandalism

{{comic
| number = 1732
| date = September 12, 2016
| title = Earth Temperature Timeline
| before = [[#Explanation|↓ Skip to explanation ↓]]
| image = earth_temperature_timeline.png
| titletext = [After setting your car on fire] Listen, your car's temperature has changed before.
}}

{{TOC}}
==Explanation==
This comic is a [[:Category:Timelines|timeline]] on how the temperature has changed from 20,000 BCE (Before {{w|Common Era}}) to the present day (2016), with three predictions for the rest of the 21st century depending on what actions are taken (or not taken) to stop CO₂ emission. This comic is a direct, but much more thorough, follow up on the previous global warming comic: [[1379: 4.5 Degrees]]. By having readers scroll through millennia of slow-paced natural changes, Randall uses the comic to confront the rapid temperature rise in recent years.

Over the past 100 years, human action has produced a large amount of {{w|CO₂ emissions}}, which have caused a rise in average global temperature through the {{w|greenhouse effect}}. This is called {{w|global warming}} and is part of a {{w|climate change}}, a subject that has become a [[:Category:Climate change|recurrent subject]] on xkcd. There are still many people who claim that this is not happening, or at least that it is not caused by any human actions, called {{w|Climate change denial|climate change deniers}}. One argument of theirs is that global warming is happening for natural causes, summarized with the phrase "temperature has changed before".

This comic shows that while temperature changes have indeed occurred before, the speed of the current temperature rise is much, much faster than those measured for many previous thousands of years. The comic became so popular that [[Randall]] [[#Popularity_of_comic|postponed the release]] of his next comic to keep this one on the front page one day longer.

The temperature curve is a dotted line most of the time, but from about 1850 to 2016 the measurement data is good enough to let the curve become a solid line indicating that this is not an estimate. Before 1850 the temperature is an estimate based on the [[#Sources|sources]] given. And likewise into the future the three possible curves are also dotted to show that they are predictions, based on how seriously the population of Earth takes knowledge (and comics) like this.

Although this is a topic Randall obviously takes very seriously, and by far most of the facts fit with known history, he still includes several [[#Jokes in the comic|jokes in the comic]]. See also the [[#Table of all elements|table]] explaining each item in the comic. After the election of {{w|Donald Trump}} for president later the year of this comic's release, it is possible that Randall believes that his worst fears (as expressed by the current path at the bottom) will hold up, with the actions taken by the new president.

The title text compares the saying that "the temperature has changed before" comparing temperature changes over thousands of years to the rapid global warming over the last century with saying that the "small" changes to the temperature a car experiences over the years of normal usage should not make you worried over the rapid temperature increase that happens when someone sets your car on fire. Randall previously used this joke in [[1693: Oxidation]].

===Jokes in the comic===
* By placing the invention of the internet at 1980 in the chart, just where the temperature curve starts its most rapid increase, Randall humorously implies that the internet caused the rise in temperature.
* At 13600 BCE a glacier is shown retreating from New York because of the warm up. It is disgusted by the new changes and proclaims: ''That’s it! I’m moving to Canada!'' This is a joke on [https://www.rollingstone.com/politics/politics-news/want-to-move-to-canada-if-trump-wins-not-so-fast-100658/ an idiom said by US citizens] to protest against changes in their country. As shown in the chart, the glacier takes 5000 years (13600-8400 BCE) to cross what would become the Canadian border (neither the United States nor Canada existed yet).{{citation needed}} Also, glaciers don't speak English, or any language for that matter.{{Citation needed}}
* At 13400 BCE it is mentioned that {{w|origin of the domestic dog|humans domesticate dogs}}. [[Megan]] talks to a wolf about to be tamed making a deal with it, that it can eat and sleep with the humans as long as they can yell at it for pooping indoors. This sounds like a sweet deal for the wolf until [[Cueball]] mentions that they will {{w|Dog breeding|breed}} it to be {{w|Chihuahua (dog)|very small}} and then dress it up in small {{w|Dog's fashion|costumes}}. The wolf says wait, but it is already too late...
* The {{w|Pokémon}} reference at 9000 BCE about them going extinct in North America (although Megan, immediately underneath, does note that this is not a real fact). As the writing stated that ''Pokemon go extinct'' this can also be seen as a reference to a popular video game called {{w|Pokémon Go}} and hence also the comic [[1705|1705: Pokémon Go]].
* At 4500 BCE, next to "{{w|Proto-Indo-European language}} develops", [[Ponytail]] gets the idea to develop the language heavily inflected to make it difficult to remember all the verb endings for future students. This is a direct reference to the comic [[1709: Inflection]].
* The reference to the 1984 {{w|mockumentary}} about the fake rock band {{w|This Is Spinal Tap}} in conjunction with {{w|Stonehenge}} at 2200 BCE. In the movie the band ordered a giant 18 feet Stonehenge megalith but a writing mistake gives them one that is only 18 inches high.
**Another real band {{w|Nine Inch Nails}} is referenced 16000 BCE where Megan writes the band's stylized name NIИ on the wall next to [[Hairy]] who is in the process of painting the {{w|cave painting}} at {{w|Lascaux}} in France.
* Around the setting of the {{w|Iliad}} and the {{w|Odyssey}} (1200 BCE) a drawing of the {{w|Trojan Horse}} has writing on it that states: ''Not a trap''.
* Just below the previous entry also at 1200 BCE is the mentioning of the invasion of the {{w|Sea Peoples}}. This sounds so much like a reference to {{w|Mermaid|mermaids}}, often called {{w|Mermaid#One_Thousand_and_One_Nights|sea people}} that Randall feels the need to note that this invasion and these sea people is ''a real thing'' in a footnote. This is opposed to the Pokémon reference above where he notes that it is ''not a real fact''. The sea people was a seafaring confederation of groups known to have attacked ancient Egypt and other Bronze age civilizations around this time. It is widely regarded to be one of the major causes of the {{w|Late Bronze Age collapse|Bronze Age Collapse}}.
* The reference at 450 BCE compares the {{w|Battle of Thermopylae}} (also known as 300 Spartans) with the dramatized 2007 movie ''{{w|300 (film)|300}}'', but in the real world the fighting of course occurred [https://youtu.be/FCfdyroV7kc?t=12 at regular speed and with more clothing].
*There are other minor jokes but this list mentions all the major jokes.

===Table of all elements===
*Here is table including all elements in the chart with explanations including reading off temperature and year for each event from the curve.
**The year group is just an easy way to find the section.
**Element is a description mainly taken from the transcript.
**The actual year of an event has been read off more precisely on the chart.
***The central part of the element has mainly been used.
***Only rarely has ranges below 100 years been used but if a location is clearly midway between two hundred years intervals 50 year range has been used.
***Only when there are several posts close to each other has smaller range been used a few times.
**T (°C) is the number of degrees Celsius above or below the 1961-1990 average, which on this graph is set to zero, (i.e. not the number of physical degrees above or below this 0°C).
***These have been read of to 0.1°C rounding up or down. Lines have been inserted over the chart, 10 for each degree, to make this as accurate as possible.
***In a few cases where a maximum is reached 0.05°C has been used
**Explanation of each element.
{| class="wikitable"
!Year group
!Element
!Year
!T (°C)
!Explanation
|-
| rowspan="2"| 20000 BCE
| [An arrow goes from the dotted line to the central line at 0°C (representing the 1961-1990 average). In the middle of the line there is a temperature label:] 4.3°C At the start of our timeline, 22,000 years ago, Earth is 4°C colder than during the late 20th century. || 20000 BCE || -4.3 || The scale here is relative, showing the magnitude of change rather than an absolute temperature reading. As a rule, {{w|climate}} changes are compared with a 30 year interval, and the 1961-1990 average was {{w|Climate#Definition|chosen for convenience}} as the "normal" to compare temperature changes with, but any other choice of baseline would show the exact same changes. The {{w|Last glacial period}} (aka ice age) reached its {{w|Last Glacial Maximum|maximum extent}} approximately 22 to 24 thousand years ago.
|-

| {{w|Boston}} is buried under almost a mile of ice, and the {{w|glaciers}} reach as far south as {{w|New York City}}. [The Statue of Liberty is shown in front of a glacier front. [[Knit Cap]] is seen in the snowy landscape. The skyline of Boston is shown under a half a mile of ice.] || 19700 BCE || -4.3 || This shows what a difference 4 degree in global temperature means (massive effect), as opposed to four degrees on a daily weather wise scale (trivial). The Boston image is directly taken from [[1225: Ice Sheets]] about the ice age glacier coverage; it was also shown buried in ice in [[1379: 4.5 Degrees]].
|-
| rowspan="3"| 19500 BCE
| But the world is about to warm up. || 19500 BCE|| -4.3 || The warming process actually takes thousands of years, which this comic will portray down thousands of pixels to come. This is not a fast warm up, especially not compared to the one we are currently experiencing (at the bottom of the chart).
|-
| By this time, humans have already spread across {{w|Africa}}, {{w|Eurasia}}, and {{w|Australia}}. || 19300 BCE || -4.3 || {{w|Homo Sapiens}} successfully {{w|Recent_African_origin_of_modern_humans#Movement_out_of_Africa|migrated out of Africa}} somewhere between {{w|Recent_African_origin_of_modern_humans#Dating:_pre-or_post-Toba|130,000}} and {{w|Recent_African_origin_of_modern_humans#Coastal_route|70,000}} BCE.
|-
| They’ve created {{w|painting}}, {{w|pottery}}, {{w|rope}}, and {{w|Bow and arrow|bows and arrows}}, but haven’t developed {{w|writing}} or {{w|farming}}. || 19100 BCE || -4.3 || The {{w|History of painting#Pre-history|oldest known paintings}} date back to about 38,000 BCE. The {{w|Ceramic_art#History|oldest known pottery}} date back to about 20,000 BCE. The {{w|Rope#History|oldest known rope}} date back to about 26,000 BCE. The {{w|History_of_archery#Stone_Age_and_Bronze_Age_archery|oldest known arrows}} date back to about 70,000 BCE, but Randall seems to be mistaken about the bows which seems to be {{w|History_of_archery#Stone_Age_and_Bronze_Age_archery|at most 10,000 years old}}. Writing is mentioned again at 3500 BCE and farming at 10,000 BCE.

|-
| rowspan="2"| 19000 BCE
| Changes in the Earth’s orbit mean that more sunlight reaches the polar ice… || 18600 BCE || -4.2 ||{{w|Milankovitch cycles}} are repeated climate variations on a timescale of tens of millennia caused by cyclic variations in {{w|Orbital eccentricity|eccentricity}}, {{w|axial tilt}}, and {{w|precession}} of the {{w|Earth's orbit}}, which thus then determined climatic patterns on Earth. The Milankovitch cycles are referenced again around 4700 BCE.

|-
| [A line chart with a labeled Y-axis "Summer sun W/m2 at 60°N" with three labeled ticks ranging from 450-550. The curve starts up and then goes down five times and up four times ending down. There is one plateau towards the end compared to the rest of the curve where the ups and downs are quite alike.] || 18600 BCE || -4.2 || The chart shows the input of sun during summer time in the {{w|Northern hemisphere}} (at {{w|60° northern latitude}}) as the effect (W) per square meter (m2) which fluctuated in the range from 450-550 during the time shown in the chart. There is, however, no scale for the time between the peaks. This chart relates to the text about increasing sun to the polar ice in the entry above.

|-
| rowspan="1"| 18500 BCE
| [A map of the world. At the top is a light gray area covering {{w|North America}}, {{w|Greenland}} and northern {{w|Europe}} and most of the northern part of {{w|Russia}}. A similar gray area covers {{w|Antarctica}}. The gray areas are labeled as ice.] || 18300 BCE || -4.2 || This [[:Category:Maps|map]] shows where the ice covered the {{w|northern hemisphere}} (and Antarctica) during the {{w|Last Glacial Maximum}}. The continents have not moved much since then, but the lower water level caused by the amount of water bound up in the ice, can clearly be seen in several locations. For instance, the {{w|British islands}}, Greenland, and {{w|Papua New Guinea}} are connected to their respective neighboring continents. Also {{w|Alaska}} and Russia are connected through the ice sheets covering the northern part of the Earth.
|-
| rowspan="1"| 18000 BCE
| …And the ice sheets start to melt. || 17900 BCE || -4.1 || This was a slow process that takes 10,000 years. The ice is mentioned again at 13,600 and 8400 BCE.

|-
| rowspan="1"| 17500 BCE
| Temperatures have been creeping upward, but around this point, CO2 levels start to climb…|| 17300 BCE || -4.1 || Due to the release of gasses from various sources (dissolved in the ocean, trapped in {{w|permafrost}}, etc), {{w|Carbon dioxide in Earth's_atmosphere#Measuring ancient-Earth carbon dioxide concentration|atmospheric CO2 levels}} increased by 100 parts per million over a span of thousands of years. Modern civilization has added the same amount in a single century.

|-
| rowspan="1"| 17000 BCE
| …And then the warming speeds up. || 16700 BCE || -4.1 || It took 3000 years for the temperature to increase with one degree. So this sentence can be seen as sarcasm about the rate of natural climate change compared to modern {{w|anthropogenic}} (human caused) warming.

|-
| rowspan="1"| 16500 BCE
| [Cueball is standing with a spear just the right of the graph talking to a rabbit.] Cueball: Still pretty cold. || 16200 BCE || -4.0 || True, because although the temperature has risen with 0.3°C over the last 4000 years, it's still 4°C below the 1961-1990 average.

|-
| rowspan="2"| 16000 BCE
| [Megan touches the dotted line to the right of her, with Ponytail standing on the other side. The graph has finally passed the -4°C line below the 1961-1990 average.] || 15600 BCE || -3.9 || Megan is the first drawing on the left side of the curve. She seems to be pushing the temperature up.
|-
| [In the right part of the chart is an explanation of the data. Below the first two lines there are four drawings each showing possible temperature swings in reality compared to the smoothed data that represents the dotted curve of the entire chart. The dotted curve is shown in all four drawings and a thin line is shown running along it but with much more fluctuation left and right on the first two, a large spike right on the third and a large bump way right on the fourth. Above these there are two labels. The first labels is inside a bracket that covers the first three, and the last label is for the last drawing. Below is a list of sources.] Limits of this data: Short warming or cooling spikes might be “smoothed out” by these reconstructions but only if they’re small or brief enough. Possible Unlikely Reconstructions are from Shakun (2012) and Marcott (2013), scaled to Annan + Hargreaves (2013) estimate for the last glacial period. || 15600 BCE || -3.9 || This is Randall's pre-emptive response to skepticism about the accuracy of prehistoric data. {{w|Ice cores}} and similar records might miss individual year-to-year variation, but should catch sustained changes lasting many decades, which is the time scale that matters for climate. See links to the [[#Sources|sources below]].

|-
| rowspan="1"| 15500 BCE
| In what is now {{w|France}}, humans paint murals on the walls of the {{w|Lascaux}} caves [Hairy paints three animals, two with horns, and two humans, Cueball holding hand with Hairy who has a spear. On the other side of the central line Megan writes three letters, the last of which is reversed:] NIИ || 15200 BCE || -3.8 || A reference to the industrial techno band {{w|Nine Inch Nails}} as Megan writes the bands stylized name NIИ on the wall next to Hairy who is in the process of painting part of the {{w|cave paintings}} at Lascaux in France.

|-
| rowspan="1"| 15000 BCE
| Ice sheets around {{w|Alaska}} shrink, exposing a land bridge between Asia and North America [From around the bottom if this section and down to 11500 BCE the dotted curve moved steadily to the right towards warmed temperature peaking close to 1.5°C below the 1961-1990 average. Before this the temperature had not moved much away from that at the start.] || 14600 BCE || -3.5 || This land bridge is known as {{w|Beringia}}. It is mentioned again at 8300 when it disappears due to the rising seas.
|-
| rowspan="1"| 14500 BCE
| [Cueball walks right looking back at the graph behind him. Megan walks in front of him pointing further right.] Cueball: Cool. Humans reach {{w|North America}}. || 14200 BCE || -3.3 || This is approximately when the humans from {{w|Asia}} crossed the land bridge mentioned in the previous entry, from what is now {{w|Siberia}} to what is now {{w|Alaska}}. {{w|Settlement of the Americas}} occurred around the time shown in the chart, although {{w|Settlement_of_the_Americas#Chronology|it's possible}} that earlier humans did so by boat prior to the formation of the land bridge. Cueball's comment is a double entendre; it was figuratively "cool" that early people migrated this far, and the climate was literally cool compared to modern times.

|-
| rowspan="2"| 14000 BCE
| The edge of the ice withdraws from {{w|New York City}} and retreats north. || 13700 BCE || -3.1 || Even though the ice began to melt 4000 years before (at 18,000 BCE in the chart) it is first now that New York City is free of ice.
|-
| [A large glacier front speaks in a speech bubble with an arrow pointing at it. Behind is there are four peaks in the horizon and in front of it three small melting pools and some rocks on the ground.] Glacier: ''That’s it! I’m moving to Canada!'' || 13600 BCE || -3.0 || When US citizens are unhappy with changes in their country, they sometimes say they will move to Canada in protest. Here it is the glacier that is anthropomorphically unhappy with the climate changes. However this is a slow process; it crosses the Canadian border more than 5000 years later.

|-
| rowspan="2"| 13500 BCE
| Humans domesticate dogs (Date uncertain, may be much earlier) || 13400 BCE || -3.0 || See {{w|Origin of the domestic dog}}. This timeline event is not quite accurate. The first dogs differentiated from {{w|Gray wolf|wolves}} about {{w|Origin_of_the_domestic_dog#Time_of_domestication|23,500 years ago}}, but there was an event around 13500 BCE that increased the population size and may be attributable to domestication events.
|-
|| [Megan and Cueball is watching a wolf looking at them.] Megan: Okay, you can live in our homes and we’ll feed you, but we’ll still get mad if you poop on the floor. Wolf: Deal. Cueball: And we get to breed you to be tiny and dress you in little costumes. Wolf: …Wait. || 13100 BCE || -2.8 || Megan is making a deal with the wolf that it can eat and sleep with the humans as long as they can yell at it for pooping indoor. This sounds like a sweet deal for the wolf until Cueball mentions that they will {{w|Dog breeding|breed}} it to be {{w|Chihuahua (dog)|very small}} and then dress it up in small {{w|Dog's fashion|costumes}}. The wolf says wait, but it is already too late...

|-
| rowspan="2"| 13000 BCE
| {{w|Woolly Rhino}} goes extinct || 12900 BCE || -2.7 || Mainland woolly rhinos died in the {{w|Quaternary extinction event}}, but a small island population survived until {{w|Woolly_rhinoceros#Extinction|around 8000 BCE}}. Woolly rhinos likely became extinct in part due to {{w|Holocene extinction|over-hunting}}. Randall's choice of species on this chart seems to focus on animals that were greatly affected by humans, for good or ill.
|-
| {{w|Oregon}} is scoured by huge floods as glacial dams burst and lakes of meltwater flow to the sea || 12600 BCE || -2.2 || This is a reference to the {{w|Missoula Floods}} several cataclysmic floods that swept periodically across eastern {{w|Washington}} and down the {{w|Columbia River Gorge}} flooding much of eastern Washington and the {{w|Willamette Valley}} in western Oregon at the end of the last ice age. During the last {{w|deglaciation}} ice dams formed then burst several times between 13,000 and 11,000 BCE.

|-
| rowspan="1"| 12500 BCE
| Ice sheets withdraw from Chicago || 12200 BCE || -1.8 || The next step towards the Canadian border, after they left New York at 13,600 BCE.

|-
| rowspan="1"| 12000 BCE
| Humans settle {{w|Abu Hureyra}} in {{w|Syria}} || 11550 BCE || -1.6 || A well-preserved prehistoric village that existed from 11,000 to 7000 BCE (a little later than noted in the chart), allowing archaeologists to study how their culture developed.

|-
| rowspan="1"| 11500 BCE
| [An arrow on the left side of the dotted curve is pointing down along the dotted curve and to the left indicate temperature is declining again, meaning the dotted curve now moves left to colder temperatures. This only continues until 10500 BCE. It is only the second time something is noted on the left side after Megan at 16000 BCE] Temperatures start to decline, mainly in the Northern hemisphere This may be caused by changes in ocean circulation due to the floods of cold fresh meltwater flowing into the Atlantic as the North American ice sheet melts. This cooler period is called the {{w|Younger Dryas}} || 11300 BCE || -1.6 || In the Younger Dryas, the Earth cooled by almost one degree over 1000 years. There were {{w|Outburst flood#Glacial_floods_in_North_America_.288.2C000_to_15.2C000_years_ago.29|several floods}} during the end of the ice age but the most famous is the one from {{w|Lake Agassiz}}. A similar but less global effect could occur if the ice on {{w|Greenland}} melts too quickly and causes a {{w|shutdown of thermohaline circulation}}. Without the {{w|Gulf Stream}}, hot water would remain in the Gulf of Mexico and the Caribbean instead of warming the {{w|North Atlantic}} and Europe. The movie {{w|The Day After Tomorrow}} dramatized a worse-than-worst-case version of this, happening in days instead of centuries.

|-
| rowspan="1"| 11000 BCE
| [This is the first text to the left of the dotted curve:] Humans reach {{w|Argentina}} || 10900 BCE || -1.8 || The earliest evidence of {{w|Indigenous_peoples_in_Argentina#Prehistory|humans in Argentina}}. Finally the temperature graph has risen enough that there is space to write text on the left side of the curve.

|-
| rowspan="2"| 10500 BCE
| [An arrow pointing down along the right side of the dotted curve and to the right indicate temperature is increasing again, meaning the dotted curve now moves right to hotter temperatures. This continues until 8000 BCE where it levels out just above the 1961-1990 average.] Warming resumes || 10500 BCE || -1.8 || After 1000 years of slightly decreasing temperatures the warm up of Earth resumes. Over the next 3000 years the temperature increases 2.5°C, reaching a long plateau about 0.5°C above the 1961-1990 average around 7500 BCE.
|-
| Human settlements at {{w|Jericho}} ||10050 BCE || -1.4 || The {{w|Jericho#Pre-Pottery_Neolithic.2C_c._9500_BCE|first permanent settlement}} on the site of Jericho occurred around 9500 BCE, but there is evidence of {{w|Jericho#Natufian_hunter-gatherers.2C_c._10.2C000_BCE|non permanent settlement}} during this period, when cold and drought made permanent habitation in that region difficult.

|-
| rowspan="1"| 10000 BCE
| First development of {{w|farming}} || 9750 BCE || -1.1 || This is now called the {{w|Neolithic Revolution}}, i.e. the wide-scale transition of many human cultures from a lifestyle of {{w|Hunter-gatherer|hunting and gathering}} to one of {{w|agriculture}} and settlement. The {{w|history of agriculture}} began independently in several locations with both {{w|domestication}} of animals and the farming of different {{w|cereals}}. One of the first regions to develop farming was the {{w|Fertile Crescent}}. This is also around this time that the last ice age is said to have ended.

|-
| rowspan="2"| 9500 BCE
| {{w|Saber-toothed cat}} goes extinct || 9200 BCE || -0.3 || Although one of these (Smilodon) was known as the {{w|saber-toothed tiger}}, most saber-toothed "cats" are not related to tigers, or any modern {{w|cats}} at all, but can be viewed as examples of convergent evolution. {{w|Smilodon}} became extinct around 8000 BCE, and the last Saber-toothed cat first became extinct around 7000 BCE, which does not fit very well with Randall's range. Indirectly humans may have caused the extinction of the Saber-toothed cat by over-hunting their {{w|megafauna}} prey, depriving the cats of food sources.

|-
| {{w|Horses}} disappear from {{w|North America}} || 9100 BCE || -0.2 || The {{w|evolution of the horse}} began millions of years ago in North America; early species {{w|Evolution_of_the_horse#Miocene_and_Pliocene:_true_equines|migrated across Beringia into Eurasia}} before their predecessors {{w|Evolution_of_the_horse#Pleistocene_extinctions|died out}}.

|-
| rowspan="4"| 9000 BCE
| | Last North American {{w|Pokémon}} go extinct [Cueball with a spear and Megan is looking up at this last “fact”.] Megan: That is not a real fact. || 8900 BCE || -0.1 || Pokemon are not real. This faux-extinction is likely a reference to the {{w|Pokémon Go}} game, which Randall spoofed in [[1705|1705: Pokémon Go]]. Virtual Pokémon now thrive throughout the entire world, and are most commonly found near [http://time.com/4443225/pokemon-go-affluent-white-neighborhoods-report/ affluent first world neighborhoods].

|-
| Temperatures reach modern levels || 8800 BCE || 0.0 || It took 11,200 years for the temperature to increase 4.3°C. It's possible that human-created effects will produce an equal change in a few hundred years.
|-
| Rising seas cut off the {{w|land bridge}} between North America and Asia || 8700 BCE || 0.1 || {{w|Beringia}} was freed of ice in 15,000 BCE. This is an example of what happens when the temperature rises and glaciers melt. Sea levels are rising again as ice on {{w|Greenland}} and {{w|Antarctica}} continues to melt.

|-
| {{w|Cattle}} domesticated || 8500 BCE || 0.2 || Cattle feature prominently in the comic [[1338: Land Mammals]].

|-
| rowspan="2"| 8500 BCE
| Ice sheets retreat across the Canadian border || 8400 BCE || 0.3 || Finally the glacier that began retreating from New York around 13,600 BCE succeeded in moving to Canada as it had threatened to do...
|-
| Temperatures start to level out slightly above 1961-1990 levels || 8050 BCE || 0.4 || The next 3000 years the temperature stays within 0.2°C degree of a temperature 0.5°C above the 1961-1990 average. A very long and stable period.

|-
| rowspan="1"| 8000 BCE
| [The above sentence breaks over the 8000 BCE line. From here a maximum in temperature on the chart is reached at 0.5°C above the 1961-1990 average, which will not be overtaken until 2000 CE. It stays almost constant here until 5000 BCE where a slight cooling begins.] || 8000 BCE || 0.4 || This is the only five hundred year span with no events listed fully inside. Maybe because nothing happens with the temperature.

|-
| rowspan="2"| 7500 BCE
| This warm, stable period is called the {{w|Holocene Climate Optimum}} || 7400 BCE || 0.5 || Some skeptics like to say "[http://www.skepticalscience.com/10000-years-warmer.htm it was warmer in the Holocene]." This is no longer true. Global temperature began encroaching Holocene levels in 1998, and has equaled or possibly exceeded them since 2014.
|-
| {{w|Jiahu}} settled in China || 7050 BCE || 0.5 || Jiahu is another prehistoric settlement, similar to Abu Hureyra (12000 BCE), that was extensively studied by archaeologists.

|-
| rowspan="2"| 7000 BCE
| Final collapse of the North American ice sheet leads to rapid 2-4m sea level rise… || 6800 BCE || 0.55 || The temperature almost reached 0.6°C above the 1961-1990 average before this happened and caused the slight decrease in temperature mentioned below.
|-
| [A small arrow points down and left to the right of the dotted curve. There is a small decrease in temperature but it is very small and would have been missed without the arrow and label.] …And a period of cooling in the Northern hemisphere || 6550 BCE || 0.5 || A 0.05 degree decrease in 200 years again refers to the theme of slow natural climate change.

|-
| rowspan="1"| 6500 BCE
| As seas rise to near their modern levels, Britain is cut off from mainland Europe || 6300 BCE || 0.45 || This is a reference to the flooding of {{w|Doggerland}}.

|-
| rowspan="1"| 6000 BCE
| Humans develop copper metalworking || 5600 BCE || 0.5 || The {{w|copper age}} was relatively brief before humans discovered how to make {{w|bronze}}.

|-
| rowspan="2"| 5500 BCE
| Massive volcanic eruption in {{w|Oregon}} creates crater lake || 5300 BCE || 0.55 || {{w|Crater Lake}} is the caldera at the top of Mount Mazama, a collapsed stratovolcano. If it erupted again, it could become a Somma volcano (see [[1714: Volcano Types]]).
|-
| {{w|Gold}} metalworking || 5050 BCE || 0.6 || The temperature peaks here at just a bit more than 0.6°C above the 1961-1990 average. It will not rise above this level until the global warming sets in in the 1900s.

|-
| rowspan="2"| 5000 BCE
| {{w|Invention of the wheel}} || 4900 BCE || 0.6 || Wheels are one of the most important inventions of humanity. They feature in many xkcd comics, such as [[1075: Warning]].
|-
| [To the right of the dotted curve is an arrow pointing down and slightly left. From here temperature decreases very slowly but steadily from 0.5°C above the 1961-1990 average until 1000 BCE where a stable plateau is reached around the 1961-1990 average.] Earth begins to cool slowly mainly due to regular cycles in its orbit || 4800 BCE || 0.5 || Again a reference to the {{w|Milankovitch cycles}} mentioned in detail at 18,600 BCE. Here they cause a cooling rather than a heating as they did back then.

|-
| rowspan="3"| 4500 BCE
| {{w|Proto-Indo-European language}} develops || 4400 BCE || 0.5 || Most of the languages in Europe, the Middle East, and India share a surprising number of common roots. PIE is the theoretical ancestor from which they descend. Randall mentions this language family in many comics, such as [[890: Etymology]].
|-
| [To the right of the curve Ponytail holds up a hand towards Cueball.] Ponytail: Let’s make our language heavily inflected, so future students have to memorize a zillion verb endings! Cueball: Okay! || 4400 BCE || 0.5 || Ponytail gets the idea to develop the language heavily inflected to make it difficult to remember all the verb endings for future students and Cueball is okay with that. This is a direct reference to the comic [[1709: Inflection]].
|-
| Permanent settlements in the {{w|fertile crescent}} || 4200 BCE || 0.5 || The Fertile Crescent is one of those things you're supposed to remember from grade school. A lot of historic milestones happened there, such as the pyramids of Giza, the code of Hammurabi, and the Abrahamic religions.

|-
| rowspan="2"| 4000 BCE
| Horses domesticated || 3950 BCE || 0.5 || Horse riding was the greatest advance in land travel until the invention of engines. Horses appear in many xkcd comics, such as [[936: Password Strength]].
|-
| {{w|Minoan culture}} arises on Crete || 3700 BCE || 0.5 || Minoan culture invented many strange and wonderful things, such as the Labyrinth at Knossos and {{w|Bull-leaping}}.

|-
| rowspan="4"| 3500 BCE
| {{w|Egyptian mummification}} || 3500 BCE || 0.5 || xkcd has discussed mummification in {{what if|134|What If? 134: Space Burial}}.
|-
| Rise of the {{w|Indus Valley civilization}} || 3300 BCE || 0.5 || The largest bronze-age civilization.
|-
| Invention of {{w|writing}} in {{w|Sumer}} “{{w|prehistory}}” ends, “{{w|history}}” begins || 3200 BCE || 0.5 || Our knowledge of prehistoric events must rely on digging up artifacts and making inferences. After this time, it became possible to find descriptions of past people and events, which is the definition of history. (Old guy in Sumer: Kids these days with their new-fangled stone tablets, instead of using their memory...)
|-
| Earliest human whose name we know (Pharaoh {{w|Iry-Hor}} in Egypt) || 3100 BCE || 0.5 || The first named person we know of today! This was also mentioned as a "cool fact" in the title text of [[1355: Airplane Message]].
|-
| rowspan="5"| 3000 BCE
| {{w|Three Sovereigns and Five Emperors}} period in China || 2800 BCE || 0.4 || The temperature has finally dropped below 0.5°C above the 1961-1990 average after almost 2000 years of cooling from 0.6°C above the 1961-1990 average.
|-
| {{w|Gilgamesh}} || 2700 BCE || 0.4 || Gilgamesh was probably a Sumerian king whose tales were exaggerated into mythology.
|-
| {{w|Imhotep}} || 2600 BCE || 0.4 || Imhotep was not a pharaoh, but a wise commoner who was elevated to chancellor, high priest, and post-mortem divinity.
|-
| {{w|Maya civilization|Mayan}} culture emerges || 2600 BCE || 0.4 || Like the ancient Egyptians, Mayans are remembered for pyramids and {{w|logograph}}s.
|-
| {{w|Great Pyramid}} constructed || 2650 BCE || 0.4 || xkcd has discussed pyramids in [[1717: Pyramid Honey]] and {{what if|95|What If? 95: Pryamid Energy}}.

|-
| rowspan="3"| 2500 BCE
| {{w|Corded Ware culture}} in Europe || 2500 BCE || 0.3 || The term Corded Ware was invented by an archaeologist; no civilization actually called themselves that.
|-
| [To the left of the curve two rock musicians with long hair and electrical guitars are standing on either side of a small gate made of three slabs of stone, one on top of the other two standing stones.] {{w|Stonehenge}} completed || 2200 || 0.3 || This is a reference to the 1984 {{w|mockumentary}} about the fake rock band {{w|This Is Spinal Tap}}. In the movie the band wanted a giant Stonehenge prop 18 feet high, but a writing mistake gives them one that is only 18 inches.
|-
| {{w|Chariots}} developed || 2000 BCE || 0.3 || But {{w|Chariots of Fire}} came much later.

|-
| rowspan="3"| 2000 BCE
| {{w|Alphabetic writing}} developed in Egypt || 1750 BCE || 0.2 || Obligatory reference to xkcd [[1069: Alphabet]].
|-
| Last {{w|mammoth}}s on a tiny Siberian island go extinct || 1650 BCE || 0.2 || Many of the {{w|Pleistocene megafauna}} died in the {{w|Quaternary extinction event}}. Like the {{w|woolly rhino}} (see 12900 BCE) these animals likely became extinct in part due to {{w|Holocene extinction|humans hunting them}}, which may be why Randall included them in the chart. Most of the mammoths died out before 8000 BCE but {{w|Woolly_mammoth#Extinction|some survived in remote areas}} and the last known population died on {{w|Wrangel Island}} in the {{w|Arctic Ocean}} around 2000 BCE, slightly earlier than Randall shows here.
|-
| {{w|Minoan eruption}} || 1600 BCE || 0.2 || This volcano may have led to the downfall of Minoan civilization.

|-
| rowspan="5"| 1500 BCE
| {{w|Iron smelting}} || 1400 BCE || 0.1 || The beginning of the {{w|Iron Age}}.
|-
| {{w|Olmec}} civilization develops in Central America || 1350 BCE || 0.1 || No, Maggie, not Aztec, [http://vimeo.com/34002760 Olmec].
|-
| [A Trojan horse with two Cueball-like guys in front and a third standing on its back. Its back is at three Cueball’s height and its head rises to the level of the Cueball on its back. It stands on a platform with four wheel on the visible side. There is text on the horse] Setting of the ''{{w|Iliad}}'' and the ''{{w|Odyssey}}'' Text on horse: Not a trap || 1250 BCE || 0.1 || A reference to the {{w|Trojan War}} qua the drawing of the {{w|Trojan Horse}}. The horse was a big trap letting the soldiers hidden inside it into {{w|Troy}}. This explains why it has ''Not a trap'' written on it. Else they would not have taken the giant wooden horse present from their sworn enemies into their city just like that... Note that the Trojan horse isn't mentioned in the Iliad, and only recalled in passing by the characters in the Odyssey.
|-
| Invasion of the {{w|Sea peoples}}* * A real thing || 1200 BCE || 0.1 || {{w|Mermaid#One_Thousand_and_One_Nights|Sea people}} might sound like a reference to mythical {{w|mermaid}}s, so Randall feels the need to footnote that this event was ''a real thing'' (as opposed to his Pokémon reference, which he notes is ''not a real fact''). The sea peoples were a seafaring confederation of groups known to have attacked ancient Egypt around this time.
|-
| {{w|Polynesians}} explore the Pacific Ocean || 1000 BCE || 0.1 || {{w|Polynesian navigation}} was surprisingly widespread.

|-
| rowspan="8"| 1000 BCE
| [From 1000 BBC to 1000 CE the temperature is stable and very close to the 1961-1990 average.] || 1000 BCE || 0.1 || The temperature has fallen from the Holocene Optimum by half a degree to just a bit above the the 1961-1990 average. It will stay in this range for the next 2000 years.
|-
| {{w|Solomon}} || 1000 BCE || 0.1 || Solomon may have been a real historical king, but he probably did not threaten to chop a baby in half.
|-
| {{w|Iliad}} and {{w|Odyssey}} composed || 900 BCE || 0.1 || These classic myths were written more than 300 years after their supposed events. Archaeologists believe the city of {{w|Troy}} existed (and was destroyed by war around the right time period), but characters like Helen, Odysseus, and Achilles did not.
|-
| Rise of {{w|Greek city-states}} || 800 BCE || 0.1 || This is ''Sparta'', along with Athens and several others.
|-
| {{w|Neo-Assyrian Empire}} || 800 BCE || 0.1 || Hi, you may remember us from such kings as Adad-nirari and Sennacherib.
|-
| {{w|Ancient Olympic Games|First Olympics}} || 750 BCE || 0.1 || The first of the ancient Olympic Games is traditionally dated to 776 BC.
|-
| {{w|Zapotec civilization|Zapotec}} writing in modern Mexico || 600 BCE || 0.0 || Another Central American culture that fell to the Spanish invasion.
|-
| {{w|Confucius}} || 550 BCE || 0.0 || "He who knows all the answers has not been asked all the questions."

|-
| rowspan="10"| 500 BCE
| The stuff in the {{w|300 (film)|movie ''300''}}, but regular speed and with more clothing || 450 BCE || 0.0 || A reference to the {{w|Battle of Thermopylae}} by comparison with the 2007 movie ''300'' about this battle. The real Spartans wore armor, and real humans don't [http://www.google.com/search?q=300+slow-motion fly through the air in slow motion when struck].
|-
| {{w|Buddha}} || 450 BCE || 0.0 || Randall also mentions other religious figures like {{w|Jesus}} and {{w|Muhammad}}.
|-
| {{w|Nazca Lines}} || 350 BCE || 0.0 || These huge ancient drawings are difficult to see from ground level, leading some people to believe that they were intended for aliens.
|-
| {{w|Alexander the Great}} || 350 BCE || 0.0 || One of the most successful conquerors of the iron age, known for supposedly cutting the {{w|Gordian Knot}}.
|-
| {{w|Mayan hieroglyphics}} || 250 BCE || 0.0 || The {{w|Maya Calendar}} was probably created hundreds of years later.
|-
| {{w|Ashoka the Great}} || 250 BCE || 0.0 || The {{w|Edicts of Ashoka}} proselytized Buddhism across the continent.
|-
| {{w|Paper}} invented || 200 BCE || 0.0 || A significant step up from stone tablets or even papyrus.
|-
| {{w|Asterix}} || 100 BCE || 0.0 || Fictional main character in ''The Adventures of Asterix'', a comic series set around 50 BCE when {{w|Julius Caesar}} conquered {{w|Gaul}}.
|-
| {{w| Teotihuacan|Teotihuacán}} metropolis || 100 BCE || 0.0 || Another ancient city much beloved by archaeologists, even though they don't know who built it.
|-
| {{w|Julius Caesar}} || 50 BCE || 0.0 || Aside from being a conqueror, dictator, and deity, Julius had a big impact on {{w|Julian Calendar|calendars}}. The month of Quintilis was renamed July to honor him, and he was famously assassinated on the ides (middle day) of March.
|-

|-
| rowspan="8"|1 BCE 1 CE
| [Instead of a zero, there are two numbers for each of the two scales before (1 BCE) and after Christ (1 CE)] || 0 CE || -0.1 || Originally the year range went directly from 1 BC to 1 AD. The year zero has since been added for ease of mathematical and astronomical calculations.
|-
| {{w|Roman Empire}} || 1 CE || -0.1 || Julius never held the title "Emperor"; his adoptive son Augustus was the first to do so.
|-
| {{w|Jesus}} || 1 CE || -0.1 || Randall also mentions other religious figures like {{w|Buddha}} and {{w|Muhammad}}.
|-
| [To the left and erupting volcano.] {{w|Pompeii}} || 100 CE || -0.1 || The volcano is {{w|Mount Vesuvius}} which exploded in 79 CE and is famous for burying everyone in the close by city Pompeii preserving peoples bodies inside the huge amount of ash that swallowed the city very rapidly. Today it has given the archeologist lots of knowledge about the culture of that time.
|-
| {{w|Three Kingdoms}} period || 250 CE || -0.1 || Not just a series of movies and video games, but an actual thing that happened in China.
|-
| {{w|Gupta empire}} || 700 CE || -0.1 || Not as great as Ashoka, but still a pretty important time in the history of India.
|-
| Various groups take turns sacking {{w|Rome}} || 550 CE || -0.1 || 500 years is a pretty successful span for an empire.
|-
| {{w|Attila the Hun}} || 550 CE || -0.1 || He probably would not mind being remembered as one of the most infamous barbarians in history.

|-
| rowspan="4"| 500 CE
| {{w|Muhammad}} || 600 CE || 0.0 || Randall also mentions other religious figures like {{w|Buddha}} and {{w|Jesus}}
|-
| {{w|Tang Dynasty}} || 750 CE || 0.0 || A golden age in China, responsible for the development of printing, gunpowder, and many other advances.
|-
| [An arrow to the right of the dotted curve pointing down, takes a swing far out from the curve and then bends back again. The text label next to it breaks into the next 500 period. The dotted curve stays stable at the 1961-1990 average along this arrow.] {{w|Medieval warm period}} in Europe and some northern regions (too regional to affect the global average much) || 900 CE || 0.0 || Changes in ocean currents caused various regions to warm up while others cooled.
|-
| {{w|Leif Eriksson}} || 950 CE || 0.0 || Probably the first European explorer to reach North America.

|-
| rowspan="7"| 1000 CE
| [To the left a drawing of a compass with needle pointing the black end towards north east. There are labels for the four main directions (N, S, W, E) and a label next to it:] {{w|Magnetic compass}} navigation || 1050 CE || 0.0 || It's much easier to sail to the Orient when you can orient yourself.
|-
| [The dotted curve moves to the left towards lower temperature reaching a minimum around 1650 CE of about 0.6°C below the 1961-1990 average at the {{w|Little Ice Age}}.] || 1150 CE || -0.1 || This less than half a degree drop in temperature over 500 years was enough to cause the "Little Ice Age" which resulted in extended ice coverage in the winters in instance Europe. See more below at the entry for the Little Ice Age.
|-
| {{w|Genghis Khan}} || 1200 CE || -0.2 || Mongol emperor. {{w|Gengar}} is not named after him, but [http://bulbapedia.bulbagarden.net/wiki/Kangaskhan_(Pokémon) Kangaskhan] and [http://awoiaf.westeros.org/index.php/Khal the Khals] are.
|-
| {{w|Zheng He}}’s fleet explores Asia and Africa || 1400 CE || -0.3 || He explored farther than European contemporaries like Dias or de Gama.
|-
| {{w|Aztec Empire|Aztec Alliance}} || 1400 CE || -0.3 || Aztec dominance only lasted a century until Cortes arrived, but their cultural legacy is indisputable.
|-
| {{w|Printing press}} || 1450 CE || -0.3 || {{w|Johannes Gutenburg}} ushered in the {{w|Age of Enlightenment}}.
|-
| {{w|Christopher Columbus|Columbus}} || 1490 CE || -0.3 || The time given here references when Christopher Columbus reached the {{w|Americas|New World}} in 1492. The five events around 1500 CE lies very close together but it fits with Columbus fitted in just before 1500.

|-
| rowspan="2"| 1500 CE
| {{w|European Renaissance}} || 1500 CE || -0.3 || From here on, the chart has labels for each 100 year increment instead of 500, but the scale stays the same. Important events happens so much faster in these last five hundred years, there isn't enough space to write all of them, so Randall has had to be selective. He includes {{w|Isaac Newton}} but leaves out {{w|Albert Einstein}}, includes {{w|airplane}}s but leaves out {{w|car}}s, etc.
|-
| {{w|Shakespeare}} || 1600 CE || -0.4 || xkcd references Shakespeare many times, such as [[79: Iambic Pentameter]] and [[1026: Compare and Contrast]].

|-
| rowspan="2"| 1600
| {{w|Isaac Newton|Newton}} || 1650 CE || -0.4 || Isaac Newton appears in various xkcd comics, such as [[626: Newton and Leibniz]].
|-
| [To the right of the dotted curve there is an arrow pointing down that makes a swing in towards the curve and then back out again. This is the coldest it has been since 9500 BCE. It is labeled:] ”{{w|Little Ice Age}}” || 1650 CE || -0.4 || This was not a true geologic Ice Age, just a slightly chilly period when the temperature fell a fraction of a degree, but still colder than it had been through 11,000 years of human civilization. In Europe the winters were so cold that the river {{w|Thames}} {{w|Little_Ice_Age#Europe|froze over}} hard enough to hold {{w|River Thames frost fairs}} between 1607 and 1814. And in 1658 {{w|Sweden}} crossed the {{w|Danish Straits}} on foot to invade {{w|Copenhagen}} in the {{w|March Across the Belts}}. It was only possible due to the harsh winters of the Little Ice Age, demonstrating how much half a degree of climate change can mean.

|-
| rowspan="2"| 1700
| {{w|Steam engines}} || 1750 CE || -0.4 || The {{w|Age of Steam}} heralded the upsurge of human CO2 emissions.
|-
| {{w|United States Declaration of Independence|Unites States Independence}} || 1770 CE || -0.3 || On July 4, 1776.

|-
| rowspan="3"| 1800
| {{w|Industrial Revolution}} || 1825 CE || -0.3 || Not to be confused with {{w|Industrial music}} such as Nine Inch Nails.
|-
| {{w|Electrical telegraph|Telegraphs}} || 1830 CE || -0.3 || [https://youtu.be/gEGQUgWBQL4?t=56s -. --- .-- --..-- / - .... . / -- --- - .... . .-. / --- ..-. / ... .- -- ..- . .-.. / -- --- .-. ... . / .- .-.. .-- .- -.-- ... / ... . -. - / - .... . / .-.. .- -.. / --- ..- - / --- -. / .- / .... --- .-. ... .]
|-
| [After this the dotted curve becomes solid.] || 1850 CE || -0.3 || From 1850 weather records became sufficiently accurate and widespread to greatly improve the precision of climate measurements. Hence the curve stops being an estimate and thus also stops being a dotted curve and becomes solid.

|-
| rowspan="6"| 1900
| {{w|Airplane}}s || 1900 CE || -0.3 || xkcd discusses airplanes many times, such as [[726: Seat Selection]] and {{what if|30|30: Interplanetary Cessna}}.
|-
| {{w|World Wars}} || 1930 CE || -0.2 || Likewise, there are many xkcds on this topic, such as [[261: Regarding Mussolini]] and {{what if|100|100: WWII Films}}.
|-
| [The solid line takes a step to the right close to the 1961-1990 average. Over the rest of the 1900s it moves closer to the 1961-1990 average, crossing it before 2000 where it almost reaches the maximum temperature of 0.5 °C above the 1961-1990 average from earlier in 8000 BCE.] || 1940 CE || -0.2 || This is what the previous 14000 pixels of comic has been leading up to. After a laborious 20 millennia of gradual and meandering climate change, it should be clear that a full degree of warming in a single century is unprecedented in human history, and very unlikely to be natural variation.
|-
| {{w|Fossil fuel}} CO2 emissions start rapidly increasing || 1950 CE || -0.1 || The infamous [http://www.skepticalscience.com/Hockey-stick-or-hockey-league.html "hockey stick"] starts around here.
|-
| {{w|Nuclear weapons}} || 1950 CE || -0.1 || The Working Group on the 'Anthropocene' suggests dating the {{w|Anthropocene}} epoch from ~1950. The week after this comic [[1736: Manhattan Project]] with a mushroom cloud was released.
|-
| {{w|Internet}} || 1980 CE || 0.1 || The origin of the internet dates back to 1960 but it began growing rapidly in 1980. By placing the invention of the {{w|internet}} at 1980 in the chart, just where the temperature curve starts its most rapid increase, Randall uses this [[552: Correlation|correlation]] to humorously imply that the internet caused the rise in temperature. This is also where the temperature crosses the 1961-1990 average, which has to happen somewhere due to the {{w|Intermediate Value Theorem}}.

|-
| rowspan="2"| 2000
| {{w|Northwest Passage}} opens || 2000 CE || 0.4 || This was dramatic evidence that the climate had changed. When global warming removes enough sea ice to create shipping routes that never existed before, then it is clear to people that ''something'' is changing, even if they disregard who/what is responsible for the change.
|-
|[From here to present day the solid line increases rapidly and in 2016, present day, is almost reaches 1°C above the 1961-1990 average, with about 0.8°C above the 1961-1990 average.] || 2016 CE || 0.8 || '''Notice''': [http://www.skepticalscience.com/argument.php?a=11&p=2 Warming did not stop] in 1998.

|-
| rowspan="3"| 2016
| | Present day || 2016 CE || 0.8 || Today, just after the two hottest months ever measured since 1850 had ended (July and August 2016), this comic was released with the message displayed very clearly here below. Act now or fry...
|-
| [From here the curve once again becomes dotted as this is the future. After one dot it splits in two and after the first two dots another split between them occurs forming three possible future dotted curves.] || 2016 CE || 0.8 || Here stops the data and the projection into the future begins so the curve again becomes dotted. Three different scenarios are depicted.
|-
|The first curve bending down before the others, and thus to the right of the other two reaches about 1.2°C above the 1961-1990 average and then goes straight down and stops at the 2100 line. An arrow points to it from the left and a label is written partly before and the rest after the 2100 line to the left of the curve:] Best-case scenario assuming immediate massive action to limit emissions || 2100 CE || 1.2 || If humanity does all in its power to stop global warming we might be able to halt the global warming already before 2050 keeping the maximum temperature to just 1.2°C above the 1961-1990 average. Only 0.4°C above today's temperature. (Note that this is not, in fact, the absolute best-case scenario, as it assumes that no new greenhouse gasses are either added to or removed from the atmosphere in the future; the temperature rise could be kept to an even lower level if some or all of the already-emitted greenhouse gasses were removed from the atmosphere.)

|-
| rowspan="2"| 2100
| [The middle curve bends a little down after reaching 1.3°C above the 1961-1990 average, and then continues this path reaching 2°C above the 1961-1990 average in 2100. An arrow point from below to it and a label is written below the curve and below 2100 line:] Optimistic scenario|| 2100 CE || 2.0 || If all the current realistic preventions are implemented, which might not be so realistic, then we may not even stop the warming but slow it down so we "only" reach 2°C above the 1961-1990 average in 2100 CE but it would not stop there. This is half the temperature change experienced since the ice age, but the other way. This was directly referenced in the title text of [[1379: 4.5 Degrees]]: ''That's only HALF an ice age unit (IAU), which is probably no big deal.''
|-
| [The last line continues along the path from the last 16 years of the solid line reaching 4.2°C above the 1961-1990 average at 2100, almost as far on the other side of the 1961-1990 average in 150 years as it took 14,000 years to move from the other side from the start of the chart. Another arrow point to this from below with a label below the curve and below 2100 line:] Current Path || 2100 CE || 4.2 || In this last scary scenario Randall assumes the temperature keeps rising steadily by extrapolating along the slope of the last two to three years. Randall has warned about the hazards of [[Extrapolating]], but this line is in fact [http://www.skepticalscience.com/climate-best-to-worst-case-scenarios.html below the worst case predictions]. If this comes true we will reach a temperature increase taking us from the 1961-1990 average and in just 125 years to 4.2°C above this average. That is just as far above this average in that short time span as the ice age temperature was below. And it took more than 11,000 years for nature to reach such an increase. Randall already contemplated what this would be like in the +1 ice age unit (IAU) panel of [[1379: 4.5 Degrees]] two years ago, as well as in [[164: Playing Devil's Advocate to Win]] almost 10 years ago. He may get to ''enjoy quite a ride'' as he "wished" for back then.

There is no reason to assume the temperature will not keep rising past 2100 CE, so the {{w|Cretaceous Thermal Maximum|"Hothouse Earth"}} of the early {{w|Cretaceous period}} mentioned in the 4.5 degree comics +2 IAU panel might come to pass in future centuries if we continue on our current path. On the bright side, modern civilization might collapse if this trend keeps up, which would drastically cut our releases of carbon dioxide and other greenhouse gasses into the atmosphere. But then again, positive feedback from methane in melting {{w|permafrost}} might take over... Good luck Earth.
|}

===Sources===
The image attributes climate data sources as "Shakun et al. (2012), Marcott et al. (2013), Annan and Hargreaves (2013), HadCRUT4, IPCC":
* Shakun, Jeremy D.; Clark, Peter U.; He, Feng; Marcott, Shaun A.; Mix, Alan C.; Liu, Zhengyu; Otto-Bliesner, Bette; Schmittner, Andreas; Bard, Edouard (2012-04-04). [https://web.archive.org/web/20160520043848/http://www.atm.damtp.cam.ac.uk/mcintyre/shakun-co2-temp-lag-nat12.pdf "Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation"] (PDF). ''Nature''. '''484''' (7392): 49–54. doi:[https://doi.org/10.1038%2Fnature10915 10.1038/nature10915]. ISSN [https://www.worldcat.org/issn/1476-4687 1476-4687]. Archived from [https://www.nature.com/articles/nature10915 the original] on 2016-05-20.
* Marcott, Shaun A.; Shakun, Jeremy D.; Clark, Peter U.; Mix, Alan C. (2013-03-08). [https://web.archive.org/web/20130412021608/https://content.csbs.utah.edu/~mli/Economics%207004/Marcott_Global%20Temperature%20Reconstructed.pdf "A Reconstruction of Regional and Global Temperature for the Past 11,300 Years"] (PDF). ''Science''. doi:[https://doi.org/10.1126%2Fscience.1228026 10.1126/science.1228026]. Archived from [https://www.science.org/doi/abs/10.1126/science.1228026 the original] on 2013-04-12.
* Annan, J. D.; Hargreaves, J. C. (2013-02-13). [https://web.archive.org/web/20200728042751/https://cp.copernicus.org/articles/9/367/2013/cp-9-367-2013.pdf "A new global reconstruction of temperature changes at the Last Glacial Maximum"] (PDF). ''Climate of the Past''. '''9''' (1): 367–376. doi:[https://doi.org/10.5194%2Fcp-9-367-2013 10.5194/cp-9-367-2013]. ISSN [https://www.worldcat.org/issn/1814-9324 1814-9324]. Archived from [https://cp.copernicus.org/articles/9/367/2013/ the original] on 2020-07-28.
* {{w|HadCRUT|HadCRUT (Hadley Centre/Climatic Research Unit Temperature)}} - [http://www.metoffice.gov.uk/hadobs/hadcrut4/ Official site]
* {{w|Intergovernmental Panel on Climate Change}} - [http://www.ipcc.ch/ Official site]

==Transcript==
'''Note''' there are several spelling errors in the comic, so please do only correct spelling errors that are not part of the comic! See more in the [[#Trivia|trivia section]].
:[A large heading, followed by a sub-caption. Below that two lines with a statement in between:]
:<big>A timeline of Earth’s average temperature</big>
:since the last ice age glaciation
:When people say “The climate has changed before,” these are the kinds of changes they’re talking about.

:[A very long chart below the headings above is headed with a label for the scale of the X-axis above the chart. Below that a sub-caption. To the left an arrow down to the top of the chart pointing to the dotted curves starting point (at -4.3°C below the 1961-1990 average) with a label above the arrow. And arrow pointing left to the left of the center and another pointing right to the right of the center has labels. Below these is the temperature scale of the X-axis, with 9 ticks between the borders each with a label ranging from -4 to +4°C compared to the 1961-1990 average, but with another step in each direction not labeled towards to axis so the chart covers -5 to +5°C compared to the 1961-1990 average.]
:'''Temperature'''
: Compared to the 1961-1990 average
:Start
:Colder
:Warmer
:-4°C -3°C -2°C -1°C 0°C +1°C +2°C +3°C +4°C

:[To the right of the chart is a gray text standing on the side down along the outer boarder of the chart with the sources for the chart:]
: Source: Shakun et. al. (2012) , Marcott et. al. (2013), Annan and Hargreaves (2013) , HadCRUT4, IPCC 

:[The chart is split in 10 columns by the temperature scale and the borders. The two central columns are white, and then from there to the left the background becomes a faded color that changes from light blue to blue at the edge in four steps. Similarly to the right the color changes from light red to red. To the left there is a time scale taking 500 years leaps from 20,000 BCE all the way to year 1, where there are two years, one for BBC and one for CE. The 500 year leaps continue until 1500 CE and from there the steps are down to 100 years until 2100 with also present day 2016 labeled. After 1500 the CE is omitted. The labels stop there, but there is space below covering down to 2200 CE. There is clearly visible division line across the chart on the level of each of the 500 step, and fainter lines for each of the 100 steps all the way even though only the last 5 of these 100 steps are labeled. There is a similar clear line at 2016. Below each step on the Y-axis is noted, and then any text starting before the next step is noted below indented. If there are extra image belonging to text this is indented once more. The graph that the whole chart is about is a dotted line that begins at the “start” point mentioned above at -4.3°C and then begins to go straight down. It will change left and right all the way down. To being with all text and most drawings are to right of the dotted curve. Whenever something is to the left it will be noted. When it says to the left above something, and then nothing over the next, then the next will be to the right. Only at the very bottom are there more entries to the left than right. ]
:20000 BCE
::[An arrow goes from the dotted line to the central line at 0°C. In the middle of the line there is a temperature label:]
::4.3°C
::At the start of our timeline, 22,000 years ago, Earth is 4°C colder than during the late 20th century.
::Boston is buried under almost a mile of ice, and the glaciers reach as far south as New York City.
:::[The Statue of Liberty is shown in front of a glacier front. A very tiny Cueball is on top of the glacier. The drawing is labeled and so is also the glacier.]
:::New York
:::Ice
:::[Cueball (wearing a knit cap with a pom-pom is seen walking in a snowy landscape leaving black footprints behind him. He walks through the white central part of the chart.]
:::[The skyline of Boston is shown with two clear buildings among all the other. Above it is a line and in between this area has been filled with thin lines. The drawing is labeled and so is this area. Also the skyline has an arrow pointing at it with a label:]
:::Boston
:::Ice
:::Modern skyline

:19500 BCE
::But the world is about to warm up.
::By this time, humans have already spread across Africa, Eurasia, and Australia.
::They’ve created painting, pottery, rope, and bows and arrows, but haven’t developed writing or farming.

:19000 BCE
::Changes in the Earth’s orbit mean that more sunlight reaches the polar ice…
:::[A line chart with a labeled Y-axis with three labeled ticks. The curve starts up and then goes down five times and up four times ending down. There is one plateau towards the end compared to the rest of the curve where the ups and downs are quite alike.]
:::Summer sun W/m2 at 60°N
:::550
:::500
:::450

:18500 BCE
::[A map of the world. At the top is a light gray area covering North America, Greenland and northern Europe and most of the northern part of Russia. A similar gray area covers Antarctica. There are two labels in the gray area above and one in the gray area below:]
::Ice Ice
::Ice

:18000 BCE
::…And the ice sheets start to melt.

:17500 BCE
::Temperatures have been creeping upward, but around this point, CO2 levels start to climb…

:17000 BCE
::…And then the warming speeds up.

:16500 BCE
::[Cueball is standing with a spear just the right of the graph talking to a rabbit.]
::Cueball: Still pretty cold.

:16000 BCE
::[Megan points to the graph to the right of her and between her and Ponytail standing on the other side. Mean is the first drawing on the left side of the dotted curve, which has hardly moved since the beginning, only to just on the other side of 4°C.]
::[In the right part of the chart is an explanation of the data. Below the first two lines there are four drawings each showing possible temperature swings in reality compared to the smoothed data that represents the dotted curve of the entire chart. The dotted curve is shown in all four drawings and a thin line is shown running along it but with much more fluctuation left and right on the first two, a large spike right on the third and a large bump way right on the fourth. Above these there are two labels. The first labels is inside a bracket that covers the first three, and the last label is for the last drawing. Below is a list of sources.]
::Limits of this data:
::Short warming or cooling spikes might be “smoothed out” by these reconstructions but only if they’re small or brief enough.
:::Possible Unlikely
::Reconstructions are from Shakun (2012) and Marcott (2013), scaled to Annan + Hargreaves (2013) estimate for the last glacial period.

:15500 BCE
::In what is now France, humans paint murals on the walls of the Lascaux caves
::[Hairy paints three animals, two with horns, and two humans, Cueball holding hand with Hairy who has a spear. On the other side of the central line Megan writes three letters, the last of which is reversed.]
:::NIИ

:15000 BCE
::Ice sheets around Alaska shrink, exposing a land bridge between Asia and North America
::[From around the bottom if this section and down to 11500 BCE the dotted curve moved steadily to the right towards warmed temperature peaking close to -1.5°C. Before this the temperature had not moved much away from that at the start.]

:14500 BCE
::[Cueball walks right looking back at the graph behind him. Megan walks in front of him pointing further right.]
::Cueball: Cool.
::Humans reach North America.

:14000 BCE
::The edge of the ice withdraws from New York City and retreats North.
::[A large glacier front speaks in a speech bubble with an arrow pointing at it. Behind is there are four peaks in the horizon and in front of it three small melting pools and some rocks on the ground.]
::Glacier: ''That’s it! I’m moving to Canada!''

:13500 BCE
::Humans domesticate dogs
::(Date uncertain, may be much earlier)
::[Megan and Cueball is watching a wolf looking at them.]
::Megan: Okay, you can live in our homes and we’ll feed you, but we’ll still get mad f you poop on the floor.
::Wolf: Deal.
::Cueball: And we get to breed you to be tiny and dress you in little costumes.
::Wolf: …Wait.

:13000 BCE
::[Randall did not use the normal spelling for Woolly Rhino, but this is an accepted alternative spelling:]
::Wooly Rhino goes extinct
::Oregon is scoured by huge floods as glacial dams burst and lakes of meltwater flow to the sea

:12500 BCE
::Ice sheets withdraw from Chicago

:12000 BCE
::Humans settle Abu Hureyra in Syria

:11500 BCE
::[An arrow on the left side of the dotted curve is pointing down along the dotted curve and to the left indicate temperature is declining again, meaning the dotted curve now moves left to colder temperatures. This only continues until 10500 BCE. It is only the second time something is noted on the left side after Megan at 16000 BCE]
::Temperatures start to decline, mainly in the Northern hemisphere
::This may be caused by changes in ocean circulation due to the floods of cold fresh meltwater flowing into the Atlantic as the North American ice sheet melts.
::This cooler period is called the Younger Dryas

:11000 BCE
::[This is the first text to the left of the dotted curve:]
::Humans reach Argentina

:10500 BCE
::[An arrow pointing down along the right side of the dotted curve and to the right indicate temperature is increasing again, meaning the dotted curve now moves right to hotter temperatures. This continues until 8000 BCE where it levels out just above 0°C.]
::Warming resumes
::Human settlements at Jericho

:10000 BCE
::First development of farming

:9500 BCE
::Saber-toothed cat goes extinct
::[To the left:]
::Horses disappear from North America

:9000 BCE
::[To the left, Randall spelled Pokémon wrong:]
:::Last North American Pokemon go extinct
:::[Cueball with a speak and Megan is looking up at this last “fact”.]
:::Megan: That is not a real fact.
::Temperatures reach modern levels
::Rising seas cut off the land bridge between North America and Asia
::Cattle domesticated

:8500 BCE
::Ice sheets retreat across the Canadian border
::Temperatures start to level out slightly above 1961-1990 levels

:8000 BCE
::[The above sentence breaks over the 8000 BCE line. From here a maximum in temperature on the chart is reached at 0.5°C which will not be overtaken until 2000 CE. It stays almost constant here until 5000 BCE where a slight cooling begins.]

:7500 BCE
::[To the left:]
::This warm, stable period is called the Holocene Climate Optimum
::[To the left:]
::Jiahu settled in China

:7000 BCE
::Final collapse of the North American ice sheet leads to rapid 2-4m sea level rise…
::[A small arrow points down and left to the right of the dotted curve. There is a small decrease in temperature but it is very small and would have been missed without the arrow and label.]
::…And a period of cooling in the Northern hemisphere

:6500 BCE
::[To the left:]
::As seas rise to near their modern levels, Britain is cut off from mainland Europe

:6000 BCE
::Humans develop copper metalworking

:5500 BCE
::[To the left:]
::Massive volcanic eruption in Oregon creates crater lake
::Gold metalworking

:5000 BCE
::[To the left:]
::Invention of the wheel
::[To the left. To the right of the dotted curve is an arrow pointing down and slightly left. From here temperature decreases very slowly but steadily from 0.5°C until 1000 BCE where a stable plateau is reached around 0°C.]
::Earth begins to cool slowly mainly due to regular cycles in its orbit

:4500 BCE
::[To the left:]
:: Proto-Indo-European language develops
:::[To the right of the curve Ponytail holds up a hand towards Cueball.]
:::Ponytail: Let’s make our language heavily inflected, so future students have to memorize a zillion verb endings!
:::Cueball: Okay!
::[To the left:]
::Permanent settlements in the fertile crescent

:4000 BCE
::Horses domesticated
::[To the left:]
::Minoan culture arises on Crete

:3500 BCE
::Egyptian mummification
::Rise of the Indus Valley civilization
::[To the left:]
::Invention of writing in Sumer “prehistory” ends, “history” begins
::Earliest human whose name we know
::(Pharaoh Iry-Hor in Egypt)

:3000 BCE
::''Three Sovereigns and five emperors'' period in China
::Gilgamesh
::[To the left:]
::Imhotep
::Mayan culture emerges
::[To the left:]
::Great Pyramid constructed

:2500 BCE
::Corded Ware culture in Europe
::[To the left of the curve two rock musicians with long hair and electrical guitars are standing on either side of a small gate made of three slabs of stone, one on top of the other two standing stones.]
::Stonehenge completed
::Chariots developed

:2000 BCE
::[To the left:]
::Alphabetic writing developed in Egypt
::Last mammoths on a tiny Siberian island go extinct
::[To the left:]
::Minoan eruption

:1500 BCE
::[To the left:]
::Iron smelting
::Olmec civilization develops in Central America
::[A Trojan horse with two Cueball-like guys in front and a third standing on its back. Its back is at three Cueball’s height and its head rises to the level of the Cueball on its back. It stands on a platform with four wheel on the visible side. There is text on the horse]
:::Setting of the ''Iliad'' and the ''Odyssey''
:::Text on horse: Not a trap
::[To the left:]
::Invasion of the Sea peoples*
::* A real thing
::Polynesians explore the Pacific Ocean

:1000 BCE
::[From 1000 BBC to 1000 CE the temperature is stable and very close to 0°C.]
::[To the left:]
::Solomon
::Illiad [sic] and Odyssey composed
::[To the left:]
::Rise of Greek city-states
::Neo-Assyrian empire
::[To the left:]
::First Olympics
::Zapotec writing in modern Mexico
::[To the left:]
::Confucius

:500 BCE
::[To the left:]
::The stuff in the 300 (film)|movie ''300'', but regular speed and with more clothing
::Buddha
::Nazca Lines
::[To the left:]
::Alexander the Great
::[To the left:]
::Mayan hieroglyphics
::Ashoka the Great
::[To the left:]
::Paper invented
::[To the left:]
::Asterix
::Teotihuacán metropolis
::[To the left:]
::Julius Caesar

:[At the year 0, there is instead two numbers for each of the two scales before and after Christ:]
:1 BCE
:1 CE
::[To the left:]
::Roman Empire
::Jesus
::[To the left and erupting volcano.]
::Pompeii
::Three Kingdoms period
::[To the left:]
::Gupta empire
::[To the left:]
::Various groups take turns sacking Rome
::Attila the Hun

:500 CE
::Muhammad
::[To the left:]
::Tang Dynasty
::[An arrow to the right of the dotted curve pointing down, takes a swing far out from the curve and then bends back again. The text label next to it breaks into the next 500 period. The dotted curve stays stable at 0°C along this arrow.]
::Medieval warm period in Europe and some northern regions (too regional to affect the global average much)
::[To the left:]
::Leif Eriksson

:1000 CE
::[The dotted curve moves to the left towards lower temperature reaching a minimum around 1650 of about -0.6°C at the Little Ice Age.]
::[To the left a drawing of a compass with needle pointing the black end towards north east. There are labels for the four main directions and a label next to it:]
:::N
:::W E
:::S
:::Magnetic compass navigation
::[To the left:]
::Ghengis [sic] Khan
::Zheng He’s fleet explores Asia and Africa
::[To the left:]
::Aztec Alliance
::[To the left:]
::Printing press
::[To the left:]
::Columbus

:1500 CE
::European Renaissance
::[To the left:]
::Shakespeare

:1600
::[To the left:]
::Newton
::[To the right of the dotted curve there is an arrow pointing down that makes a swing in towards the curve and then back out again. At -0.6°C this is the coldest it has been since 9500 BCE. It is labeled:]
::”Little Ice Age”

:1700
::Steam engines
::[To the left:]
::Unites States Independence

:1800
::Industrial Revolution
::[To the left:]
::Telegraphs
::[After this the dotted curve becomes solid.]

:1900
::[To the left, and on the line for 1900:]
::Airplanes
::[To the left:]
::World Wars
::[The solid line takes a step to the right close to 0°C. Over the rest of the 1900s it moves closer to 0°C crossing it before 2000 where it almost reaches the maximum temperature of 0.5 °C from earlier in 8000 BCE.]
::Fossil fuel CO2 emissions start rapidly increasing
::[To the left:]
::Nuclear weapons
::[To the left:]
::Internet

:2000
::Northwest Passage opens
::[From here to present day the solid line increases rapidly and in 2016 present day is almost reaches 1°C, with about 0.8°C.]

:2016
::[To the left on the line for 2016:]
::Present day
::[From here the curve once again becomes dotted as this is the future. After one dot it splits in two and after the first two dots another split between them occurs forming three possible future dotted curves. The first curve bending down before the others, and thus to the right of the other two reaches about 1.2°C and then goes straight down and stops at the 2100 line. An arrow points to it from the left and a label is written patly before and the rest after the 2100 line to the left of the curve:]
::Best-case scenario assuming immediate massive action to limit emissions

:2100
::[The middle curve bends a little down after reaching 1.3°C and then continues this path reaching 2°C in 2100. An arrow point from below to it and a label is written below the curve and below 2100 line:]
::Optimistic scenario
::[The last line continues along the path from the last 16 years of the solid line reaching 4.2°C at 2100, almost as far on the other side of 0°C in 150 years as it took 14000 years to move from the other side from the start of the chart. Another arrow point to this from below with a label below the curve and below 2100 line:]
::Current Path

==Trivia==
*There have been several ''[[:Category:Large drawings|large drawings]]'' in the history of xkcd, some of which are bigger than this one (for instance [[1110: Click and Drag]]).
**Among those that can be viewed in one go, without downloading a larger file or moving around, this is by far the longest.
**The next longest is probably [[482: Height]].
*The timeline starts at 20,000 BCE (22,000 years ago) and ends at 2100 CE, thus covering 22,100 years.
*There are several spelling mistakes.
**Most obvious is the second time Randall wrote the word "Iliad," because he just spelled it correctly at 1500 BCE and then spelled it ''Illiad'' at 1000 BCE with two Ls.
**Attila the Hun was initially misspelt ''Atilla the Hun'' with ''one'' T and ''two'' Ls, but this was corrected at some point.
**Genghis Khan is misspelt as ''Ghengis Khan'' (a common error).
**Pokémon is spelled ''Pokemon'', but then again, that is not so strange for Randall (see [[1647: Diacritics]]). Despite that, he usually spells it correctly, as in [[1705|1705: Pokémon Go]].
**Note that the fact that woolly rhinoceros becomes ''Wooly rhino'' with only one l is not a spelling mistake but an alternative spelling of the word.
*The following notable facts are absent
**1850: methodical temperature record begins. However, this fact is indirectly indicated when the temperature curve becomes solid around 1850 and until present day.
**The entire swing period between 20 and 200 thousand years prior to now would depict temperature swings with increasing frequency and amplitude (ref geological record). But of course, this could not be included in a comic that only goes back to 20,000 BCE.
**During much of the 300 million years prior to that, the Earth was significantly warmer than now. However, the data's temporal precision decreases with age; seemingly abrupt changes millions of years ago might have happened over centuries or millennia. Hence, the older data is not usable to compare rates of change.

===Popularity of comic===
This comic became popular with a much broader audience than most xkcd comics. It was discussed admiringly by news sites such as [http://www.popsci.com/xkcd-earth-average-temperature-timeline Popular Science], [http://reason.com/blog/2016/09/14/send-around-this-xkcd-climate-change-web Reason], [http://www.slate.com/blogs/bad_astronomy/2016/09/13/xkcd_takes_on_global_warming.html Slate], [http://www.smithsonianmag.com/smart-news/new-comic-masterfully-shows-how-climate-has-changed-through-time-180960451/ Smithsonian], [http://www.forbes.com/sites/ericmack/2016/09/13/heres-22000-years-of-climate-changes-in-a-single-comic/ Forbes], [https://www.vox.com/2016/9/12/12891814/climate-change-xkcd-graphic Vox], [https://www.npr.org/sections/goatsandsoda/2016/09/14/493925781/epic-climate-cartoon-goes-viral-but-it-has-one-key-problem NPR], [https://qz.com/780391/xkcd-tells-the-entire-history-of-humanity-and-climate-change-in-one-cartoon-chart/ Quartz], [https://www.sciencealert.com/why-4-5-million-years-of-fluctuating-global-temperatures-can-t-explain-climate-change-today Science Alert] and [https://www.climatecentral.org/news/climate-change-xkcd-comic-20696 Climate Central]. It was promoted by famous individuals such as [https://twitter.com/elonmusk/status/775632728548970500 Elon Musk] and even [https://twitter.com/unfccc/status/776129715799224320 twitted by the UN council on Climate Change], and obviously hated on by vocal {{rw|climate_change|climate change deniers}} and {{rw|crank|cranks}} such as [https://www.reddit.com/r/dataisbeautiful/comments/53poul/josh_takes_on_xkcds_climate_timeline/ Anthony Watts]{{rw|Anthony_Watts|debunked}} and [http://joannenova.com.au/2016/09/how-to-make-climate-graphs-look-scary-a-reply-to-xkcd/ Joanne Nova]{{rw|Joanne_Nova|debunked}}

Saying the "dotted line comes from computer models" is a bit inaccurate. Prehistoric temperature reconstructions are based on lots of measurements from lots of places around the planet: ice cores, lake and ocean sediments, etc. which are the best proxy records of climate change. From those measurements, one infers temperature, so [[Randall Munroe]] [https://www.scpr.org/news/2016/09/15/64670/epic-climate-cartoon-goes-viral-but-it-has-one-key/#comment-2900724860 may be more correct than he realises]. Calling that process computer modeling stretches the meaning of the phrase. For more {{rw|rationalist}} critique of this chart not driven by the agenda of pushing {{rw|pseudoscientific}} beliefs which are against the worldwide consensus, see [https://www.climatecentral.org/news/climate-change-xkcd-comic-20696 t][https://reason.com/2016/09/14/send-around-this-xkcd-climate-change-web/ h][https://www.npr.org/sections/goatsandsoda/2016/09/14/493925781/epic-climate-cartoon-goes-viral-but-it-has-one-key-problem i][https://www.scpr.org/news/2016/09/15/64670/epic-climate-cartoon-goes-viral-but-it-has-one-key/ s] and most insightfully, [https://scienceblogs.com/gregladen/2016/09/13/everybody-always-gets-this-wrong-even-smart-people this].

*Due to increased interest, Randall decided to push the release of the next comic [[1733: Solar Spectrum]] one day back for a rare [[:Category:Thursday comics|Thursday release]] instead of the scheduled [[:Category:Wednesday comics|Wednesday release]].
**He [http://web.archive.org/web/20160915101125/http://xkcd.com/ noted this] above [[:image:1732_Earth_Temperature_Timeline_header_text_changed_for_all_comics.png|all the comics]] in the [[:image:1732_Earth_Temperature_Timeline_header_text_changed.png|header text on xkcd]]:
::''Note: Since a lot of new people are here looking for this chart today,''
::''I'll be posting Wednesday's comic on Thursday instead.''
:*Before that, the [http://web.archive.org/web/20160912181546/https://xkcd.com/ normal heading] with the release day of xkcd was shown.
:*This was (of course) still there Tuesday the [http://web.archive.org/web/20160913231501/http://xkcd.com/ day after] the release, because it was first on Wednesday there were reason to note the delay.
:*It stayed in place even [[:image:1732_Earth_Temperature_Timeline_header_text_changed_also_when_next_comic_was_released.png|for some time after]] the "Wednesday" comic was released on Thursday, but was [http://web.archive.org/web/20160915154605/http://xkcd.com/ then removed] before [[:image:1732_Earth_Temperature_Timeline_header_text_back_to_normal_shortly_after_next_comic_was_released.png|noon (EST)]] on Thursday.
:**Randall did thus not post a link to this comic in the header text for new visitors to use, only giving them that one extra day.
:*Even though the next comic was released on a Thursday, the scheduled Friday comic [[1734: Reductionism]] was still released as planned.
:**This was also the first time this occurred on xkcd - see [[1734:_Reductionism#Trivia|this trivia item]] from the Friday comic.
*On 2019-03-01, this comic became one of the six [[Design of xkcd.com|footer]] comics.
==== Removal of warning and footnote ====
*This comic's popularity was possibly the reason that both the more-than-10-year-old [[xkcd warning]] as well as the [[footnote#Original_footnote|original footnote]] was [[footnote#Removal_of_original_footnote|removed]] on the day of this comic's release.
**The next footnote was added 22 days later.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Large drawings]]
[[Category:Charts]]
[[Category:Timelines]]
[[Category:Line graphs]]
[[Category:Maps]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring real people]] 
[[Category:Multiple Cueballs]]
[[Category:Climate change]]
[[Category:Science]]
[[Category:Animals]]
[[Category:Music]] 
[[Category:Fiction]] 
[[Category:Sport]] 
[[Category:Religion]] 
[[Category:Internet]]
[[Category:Pokémon]]
[[Category:Footer comics]]
[[Category:Puns]] 
[[Category:Volcanoes]]
[[Category:Nuclear weapons]]

767: Temper

2022-05-04T00:58:23Z

108.162.245.215: undid vandalism

{{comic
| number = 767
| date = July 16, 2010
| title = Temper
| image = temper.png
| titletext = Mr. Rogers projected an air of genuine, unwavering, almost saintly pure-hearted decency. But when you look deeper, at the person behind the image... that's exactly what you find there, too. He's exactly what he appears to be.
}}

==Explanation==
Actor {{w|Mel Gibson}} was the subject of controversy a few days before this comic came out because a telephone rant was taped and released to the public. He laughed off the call, saying simply "I have a bit of a temper."

{{w|Fred Rogers}} was a minister and television personality best known for his children's educational show ''{{w|Mister Rogers' Neighborhood}}''. He's also famous for his testimony before the US Senate Communications subcommittee to secure a much-needed increase in funding for public educational broadcasting. He died of stomach cancer on February 27, 2003, but the legacy he left is substantial; to quote Wikipedia: "Rogers received the Presidential Medal of Freedom, some forty honorary degrees, and a Peabody Award. He was inducted into the Television Hall of Fame, was recognized by two Congressional resolutions, and was ranked No. 35 among TV Guide's Fifty Greatest TV Stars of All Time. Several buildings and artworks in Pennsylvania are dedicated to his memory, and the Smithsonian Institution displays one of his trademark sweaters as a 'Treasure of American History'."

Part of what made Fred Rogers (and, by extension, ''Mister Rogers' Neighborhood'') so successful was the perpetually cheerful, genuine way he presented himself. He was always sincere, but he was polite and gentle in his sincerity. Additionally, in stark contrast to the celebrity stereotype, he was an enormously compassionate and kind-hearted person even when off the screen. People who knew him in real life often observed that the Mister Rogers shown on TV wasn't just a character, it ''was'' Fred Rogers himself - as the title text notes. This counterstereotype has fueled [http://www.snopes.com/radiotv/tv/mrrogers.asp urban legends] that he was a former child molester, that he served in the military and killed many, etc., none of which are true.

This comic subverts these false suspicions. Fred Rogers is fictionally recorded having a fight with his wife, but instead of a Mel Gibson-style explosive rage, he approaches it with a calm, diplomatic, and loving attitude consistent with his real personality. The title text does the same, setting up for a shocking reveal and failing to meet it.

==Transcript==
:[A black frame with the text [NO VIDEO] in the center, speech is in bubbles.]
:Voice: Sometimes, when we disagree, I feel frustrated. But I never forget how lucky I am to have you in my family. Always remember how special you are.
:1981: An audio recorder on the set catches Fred Rogers fighting with his wife.

{{comic discussion}}
[[Category:Romance]]
[[Category:Comics featuring real people]]

1050: Forgot Algebra

2022-05-04T00:58:06Z

108.162.245.215: undid vandalism

{{comic
| number = 1050
| date = May 2, 2012
| title = Forgot Algebra
| image = forgot_algebra.png
| titletext = The only things you HAVE to know are how to make enough of a living to stay alive and how to get your taxes done. All the fun parts of life are optional.
}}
==Explanation==
[[Megan]], standing with [[Hairy]], is an ex student of [[Miss Lenhart]] and she taunts her old algebra teacher, because she hasn't used algebra since she left school. This is a reflection of a common gripe among students: that they have no need to learn math because they assume they'll never use it after they graduate. [[Randall|Randall's]] argument is that you have the option to use what you learned in school or not. Lots of people use math after they graduate, lots of people use their music lessons, and others don't use anything they learned in school at all. However, Randall doesn't understand why someone would be proud of their own ignorance, especially since people do brag about things like being able to cook and speak other languages, which are also entirely non-essential, perhaps even more so than algebra.

However, Megan is also wrong in that she likely does use basic mathematical calculations in everyday life, even if they're not in orderly lists of parameters ending with "solve for x." For example, to turn one's apartment into a ball pit like in [[150: Grownups]], one must calculate or at least estimate (another skill learned in math class) the floor space of the room, the desired depth for the balls to cover, the space occupied by one crate of balls, and the cost of such a crate. While the operations are basic arithmetic, the ability to recognize unknowns and sort them into a meaningful statement comes from algebra.

The title text states that technically you don't "need" to do anything but survive and {{w|Death & Taxes|pay your taxes}} (although, ironically, doing one's taxes can require quite a bit of algebra), and implies that math is one of the optional and fun parts of life.

This is one of the two comics where Miss Lenhart is both drawn and named, the first being [[499: Scantron]].

==Transcript==
:[Hairy is looking on as Megan takes her hands to her mouth and yells after Miss Lenhart who is walking away while looking back at her over her shoulder.]
:Megan: Hey, Miss Lenhart! I forgot everything about algebra the moment I graduated, and in 20 years no one has needed me to solve ''anything'' for x.
:Megan: I ''told you'' I'd never use it!
:Megan: In your ''face''!

:[Caption below the panel:]
:It's weird how proud people are of not learning math when the same arguments apply to learning to play music, cook, or speak a foreign language.

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Miss Lenhart]]
[[Category:Comics featuring Hairy]]
[[Category:Math]]

1644: Stargazing

2022-05-04T00:57:27Z

108.162.245.215: undid vandalism

{{comic
| number = 1644
| date = February 17, 2016
| title = Stargazing
| image = stargazing.png
| titletext = Some of you may be thinking, 'But wait, isn't the brightest star in our sky the Sun?' I think that's a great question and you should totally ask it. On the infinite tree of possible conversations spread out before us, I think that's definitely the most promising branch.
}}

==Explanation==
This is the first comic in the [[:Category:Stargazing|Stargazing]] series. It was followed by [[2017: Stargazing 2]] two and a half years later and [[2274: Stargazing 3]] four years later.

This comic opens on [[Megan]] as the host for a {{w|stargazing}} TV show, or simply a stargazing tour. She claims to be a doctor in {{w|astronomy}} though her remarks, however enthusiastic, may call this into question. (Originally the host was suspected to be a spoof on {{w|Brian Cox (physicist)|Brian Cox}}, see [[#Relevant TV-shows|below]], but at some later point [[Randall]] changed his official transcript thus making the host female rather than male as in the original version, see the [[#Trivia|trivia]] section below. Thus now the host is clearly Megan, which it could not have been originally when the host was described as a man by Randall).

Throughout the comic the host's tone and choice of words becomes increasingly unprofessional, referring to most of the stars as "shitty," personifying them based on different astronomical observations, and providing little useful information on the study of stars or how they work.

It seems that this is not an isolated issue as the television host mentions that people keep asking her whether or not she is a real astronomer.

The host also continuously glosses over the arguably less exciting portions of a typical presentation on astronomy sharing only what she sees as "the good stuff." This penchant for only caring about something if it is interesting extends past astronomy as well as the host is too bored when reading the dictionary to look up the meaning of astronomer.

The comic derives much of its humor from the absurdity of the host's comments on various astronomical bodies. Although not technically incorrect, the way she presents the information is far from informative. (See details below on [[#The host's observations|the host's observations]]).

One of her observations regards the fact that {{w|Sirius}} is a {{w|binary star}}, a system where two stars orbit each other. So even though it is the brightest star as seen from Earth we only really see one of them, as the other is, to quote the host, "not even trying". Sirius A is "large" and "bright" {{w|main sequence}} white star, while Sirius B is a {{w|white dwarf}} with a little under half the mass, 0.49% the radius and only 0.22% the luminosity of Sirius A.

{{w|Andromeda Galaxy|Andromeda}} is the largest galaxy in our {{w|Local Group}}. It is 220,000 light years across and contains a trillion stars. Humans have difficulty conceptualizing distances of this scale. Suffice to say that it is very large.{{Citation needed}}

{{w|Betelgeuse}} is the 9th brightest star visible from earth. One of its prominent features is its visible redness. Within the next million years (or maybe only 100,000 years) it is expected to explode as a {{w|supernova}}, which will certainly be a spectacular sight. It could happen anytime now, and the host hopes it will be in her lifetime.

In the title text it is mentioned that the {{w|Sun}} is also a star and of course is much brighter than Sirius seen from Earth, and thus Sirius is technically not the brightest star in our sky (although it is in the night sky). The title text sarcastically encourages the audience to raise that obvious but irrelevant point (a standard joke when people mention bright stars) instead of asking a more interesting, informative, or fruitful question, when there are so many to ask regarding astronomy.

See also [[1371: Brightness]] and [[1342: Ancient Stars]]. Saying cool things about space to make people like you is mentioned in [[1746: Making Friends]].

===The host's observations===
Here is a list of the host's observations:
*Most {{w|Bright Star Catalogue|visible stars}} are still very faint, and just become background to the bright {{w|stars}} that form the named {{w|constellations}}.
**The host correctly states that they are just dots. (This is also true for the bright stars, but at least they are clearly distinguishable).
*{{w|Sirius}} is the {{w|Apparent magnitude|brightest}} star in our {{w|List of brightest stars|night sky}}. But it is not the brightest object in the night sky, as several of the planets, especially {{w|Venus}} and {{w|Jupiter}}, and of course the {{w|Moon}} are much brighter. It is also far from being one of the most {{w|Absolute magnitude|luminous stars}} in the {{w|Milky Way}}, but its proximity to Earth makes it the brightest in the night sky. There are {{w|List_of_most_luminous_stars#Data|twenty visible stars}} that are more luminous than Sirius, {{w|List of most luminous stars|none of which}} come even close to being in the top 100 of the most luminous stars observed today.
**The host thus names Sirius as the star in charge since it outshines all the others as seen from the {{w|Earth}}.
*Sirius is actually a star system consisting of two stars as it is a {{w|binary star}} system. But where Sirius A is twice the size of the {{w|Sun}} and much brighter, then Sirius B is now just a dim {{w|white dwarf}}, the remains from a much larger star that became a {{w|red giant}} before shedding its outer layers and collapsing into its current state around 120 million years ago. So now Sirius A completely outshines Sirius B, which actually is now a dead star with no further fusion going on inside its core.
**This is construed by the host as it is barely even trying, as it is now only radiating away the rest of the heat from the now exposed core.
*{{w|Andromeda Galaxy|Andromeda}} is a {{w|spiral galaxy}}, like the Milky Way, and it is the largest galaxy in the {{w|Local Group}} where our own galaxy the Milky Way is the second largest. It is one of a few visible objects that are located outside the Milky Way. It is "only" 2.5 million light-years from the Sun and it is heading our way (or vice versa), and will {{w|Andromeda–Milky Way collision|collide with the Milky way}} in about 4 billion years (before the Sun goes into {{w|Sun#After_core_hydrogen_exhaustion|its red giant phase}}). Being 220,000 light years across and consisting of a trillion stars, it is somewhere between 1.2-2.2 times wider than the Milky Way and has 2.5-10 times as many stars. (The local group was also mentioned two comics ago, in [[1642: Gravitational Waves]], together with the much less well known third largest galaxy in the group the {{w|Triangulum Galaxy}}).
**It is therefore true when the host says that it is too big to try to understand, and thinking about it will make your head spin, so she suggests we do not think about it.
*{{w|Betelgeuse}} is a clearly visible (9th brightest) {{w|Red_supergiant|red supergiant}} {{w|Semiregular_variable_star|variable star}} located in the {{w|Orion (constellation)|constellation of Orion}}. It is one of the largest and most luminous observable stars (12th) and one of the few where it is clear that the light is not white. Most people can see that it is slightly red, whereas most other stars are so faint that they look white despite having different colors (when seeing Orion's two brightest stars, to remember which is which between Rigel and Betelgeuse, its diagonal opposite, just remember: Rigel is "R" like blue, and Betelgeuse is "B" like red). It is expected that Betelgeuse, being at a late stage of its {{w|Stellar_evolution|evolution}}, {{w|Betelgeuse#Approaching_supernova|will go supernova}} within the next million years as a {{w|type II supernova}}. The exact time when it will become a {{w|Supernova}} is so uncertain that it could [http://earthsky.org/brightest-stars/betelgeuse-will-explode-someday#explode just as likely happen tomorrow] as in a million years. When it happens it will not be dangerous to anyone on Earth, but it will likely be visible even during the day, as it may even become as bright as the full Moon.
**When it does go nova, it will be a fantastic spectacle for everyone, but especially for anyone who likes the ''good stuff'' in space like the host, who cannot wait for the star to explode. Clearly she hopes it will be in her lifetime, and, although this is unlikely, there is a small chance that it might just happen.
*A {{w|meteor}} (also known as {{w|shooting star}}), is debris from space that rains down on Earth, and burns up in the atmosphere. This happens all the time, but you need to be either lucky, patient, or know the right time for one of the {{w|meteor showers}} to see one. Often they are visible for so short a time period, that it is difficult to share the experience with anyone, as it will be gone by the time they turn their head to look where you are pointing.
**The host becomes very excited when she spots such a meteor, especially because it is likely that her audience got to share the experience with her, as they were already looking in the same direction as her. But still she asks if they saw it, because it is so short lived.
*{{w|Outer space}} is the void that exists between {{w|Astronomical object|celestial bodies}}, including the Earth. There is by definition nothing there but {{w|vacuum}}, and the interesting part of space is thus not the space but the astronomical objects found out there.
**The host says that ''space is cool'', which is a very un-astronomical comment, as explained above. Also her excitement for a simple shooting star is cause for the suspicion that is raised after her space comment.

===Relevant TV-shows===
The comic could be a reference to BBC's ''{{w|Stargazing Live}}'', which {{w|Brian Cox (physicist)|Brian Cox}} has appeared in since 2011. If drawn in xkcd style he would likely look like Megan. He has a PhD in high-energy {{w|particle physics}}, but not astronomy. The newest season of the show aired during January 2016 just a month before this comic's release. Brian Cox has also been the presenter of several other science programs, especially such as the ''{{w|Wonders of the Solar System}}'', ''{{w|Wonders of the Universe}}'' and ''{{w|Wonders of Life (TV series)|Wonders of Life}}''. Originally the host was described as male in the official transcript (see [[#Trivia|trivia]] below, making this seem more likely. for some reason Randall changed the host to female in the transcript later. Very strange, but for sure when he was male, it was obviously a Brian Cox spoof.

It could also be a reference to {{w|Jack Horkheimer}}'s PBS shows ''Star Hustler'' and ''{{w|Star Gazers}}''. Horkheimer, however, does not at all look like Megan, and he died 6 years ago. But he was not a doctor in astronomy, only getting into it when he started volunteering at the Miami Museum of Science's planetarium. He ended up writing shows for the planetarium and the PBS series developed from there. He rarely covered facts about the night sky that couldn't be found in any basic reference (possibly because the show was aimed at children and non-astronomy buffs), although he did get more in-depth about current astronomical events such as {{W|Comet Hale–Bopp}}.

==Transcript==
:[A thin panel with Megan as a TV-host is holding her hands up. She is drawn in white on a black background. Behind her is an audience drawn in faint gray lines consisting of Hairy (to the left) and two Cueball-like guys and Ponytail (seen in a rare full face position) to the right of the host. One of the Cueball-like guys is partly hidden behind the host.]
:Host: Welcome to stargazing, with your host, me.
:Host: I'm a doctor or whatever.

:[Same scene as before but in a broader panel, and the host is now holding only one hand up with a finger pointing up. The audience is the same four people, but now Hairy has moved further to the left in the panel to make room for a Megan-like woman also to the left of the host.]
:Host: I'm not gonna waste your time on the shitty stars.
:Host: Just the good stuff.
:Host: Honestly half of 'em just look like dots.

:[A frame-less drawing with a zoom out showing the group of six people in black silhouette on a white background. Part of the ground beneath them is shown as a black pool. The host is pointing up with one hand. The people have been rearranged, so left of the host is now a Cueball-like guy and a Megan-like woman, and to the right is the other Cueball-like guy, then Ponytail (seen from the side as usual) and Hairy. All are looking up following the host's directions.]
:Host: This is Sirius. It's the brightest star in our sky so it's in charge.
:Host: It's really two stars but one of them is barely even trying.
:Host: This is Andromeda, it's too big to think about, so let's not.

:[Zoom in of the host's upper body, again drawn in white on a black background. She is looking right gesturing with one arm raised, and the other still pointing up with a finger stretched out. Her audience is no longer shown.]
:Host: That red stars is Betelgeuse. It's gonna explode someday.
:Host: Can't happen soon enough, as far as I'm concerned. I-
:Host: ''Holy shit did you see that meteor!?!''
:Host: Space is ''awesome!''

:[Same scene as the previous panel, but the host has turned towards left looking at someone in the audience (not shown) who speaks off-screen. She has taken both her hands down for the first time.]
:Off-screen voice: Are you ''sure'' you're an astronomer?
:Host: People keep asking that, so I finally tried to look that word up in a dictionary, and ''wow'' is that book ever boring. No thank you.
:Off-screen voice: But-
:Host: ''Space!''

==Trivia==
*Randall changed the [http://www.explainxkcd.com/wiki/images/archive/4/48/20160221022727!stargazing.png original] posted version of the comic.
**The only thing that changed was in the third panel where '''''That's''' Andromeda'' was changed to the current version: '''''This is''' Andromeda''
*The official transcript [https://web.archive.org/web/20160913162302/http://xkcd.com/1646/info.0.json originally] used male pronouns for the TV host. It now (as of 2019) uses female pronouns for the host.
**The official transcripts seems to have been messed up on xkcd at the time being.
***The [http://xkcd.com/1644/info.0.json transcript for 1644] is thus at the moment a mix of that comics main info (top and bottom) which results in the correct title and title text, but the entire description in this transcript is describing the comic from two releases before no. [[1642]].
***This seems to be a general problem for comics released around that time...
***Thus the description of this comic, was first released when comic no. [[1646]] came out.
***This has not been corrected (4 years later at the time of writing)!
****So the official transcript for 1644 can be found [http://xkcd.com/1646/info.0.json here], together with the data for comic 1646.
**The current transcript is included here below:
::(Inverse color panel - white on black)
::[A television host in the foreground, speaking toward the reader. A group of other people are in the background behind them.]
::Host: Welcome to Stargazing, with your host, me. I'm a doctor or whatever.
::[She continues to talk.]
::Host: I'm not gonna waste your time on the shitty stars. Just the good tuff. Honestly half of 'em just look like dots.
::(Normal color panel - black on white)
::[A shot from far away of the host standing in the center of the group of people watching her, she points to the sky.]
::Host: This is Sirius. It's the brightest star in our sky so it's in charge. It's really two stars, but one of them is barely even trying. This is Andromeda. It's too big to think about, so let's not.
::(Inverse color panel)
::[Close-up on the host gesturing toward the sky behind her.]
::Host: That red star is Betelgeuse. It's gonna explode someday. Can't happen soon enough, as far as I'm concerned. I--
::HOLY SHIT DID YOU SEE THAT METEOR?!?!
::Space is awesome!
::[The host speaks to someone out of panel.]
::Other: Are you sure you're an astronomer?
::Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you.
::Other: But--
::Host: SPACE!
:*The original official transcript with male host is included here below (correcting a typo with a missing "s" in "stuff" and formatting to look like our normal transcripts):
::[A television host in the foreground, speaking toward the reader. A group of other people are in the background behind them.]
::Host: Welcome to Stargazing, with your host, me. I'm a doctor or whatever.
::[He continues to talk.]
::Host: I'm not gonna waste your time on the shitty stars. Just the good stuff. Honestly half of 'em just look like dots.
::[Normal color panel - black on white. A shot from far away of the host standing in the center of the group of people watching him, he points to the sky.]
::Host: This is Sirius. It's the brightest star in our sky so it's in charge. It's really two stars, but one of them is barely even trying. This is Andromeda. It's too big to think about, so let's not.
::[Inverse color panel. Close-up on the host gesturing toward the sky behind him.]
::Host: That red star is Betelgeuse. It's gonna explode someday. Can't happen soon enough, as far as I'm concerned. I-- ''HOLY SHIT DID YOU SEE THAT METEOR?!?!'' Space is ''awesome''!
::[The host speaks to someone out of panel.]
::Other: Are you ''sure'' you're an astronomer?
::Host: People keep asking that, so I finally tried to look that word up in a dictionary, and ''wow'' is that book ever boring. No ''thank'' you.
::Other: But--
::Host: ''SPACE!''

{{comic discussion}}

[[Category:Stargazing]]
[[Category:Comics sharing name|Stargazing]]
[[Category:Comics with inverted brightness]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Multiple Cueballs]]
[[Category:Astronomy]]
[[Category:Space]]

1153: Proof

2022-05-04T00:55:45Z

108.162.245.215:

{{comic
| number = 1153
| date = December 28, 2012
| title = Proof
| image = proof.png
| titletext = The prosecution calls Gottfried Leibniz.
}}

==Explanation==
{{w|Zeno of Elea}} was an ancient Greek philosopher who devised several apparent paradoxes of motion called {{w|Zeno's paradoxes}}. Here are the two relevant to the comic:

:'''Arrow paradox:''' At any instant in time, an arrow suspended in mid-air is no different from an arrow in motion. How, then, can motion occur? (Answer: {{w|calculus}} [all objects have a velocity].) The lawyer presumably intends to use this argument to prove that his client could not have used the arrow to commit murder. Another possibility was that it is impossible to hit a person in motion.

:'''Dichotomy paradox:''' Suppose I need to go from point A to point B. First I must walk halfway there: half of the distance between A and B. Then I must walk half the remaining distance, which would bring me to three-quarters of the original distance; then I must again walk half the now-remaining distance to reach a point seven-eighths of the way from point A, and so on. Because I would have to take an infinite number of non-zero steps, I will never reach point B. By the same argument, the lawyer in the comic can get closer and closer to the judge's table, but never reach it.

There are two possible law vs math/logic puns in the comic, on the words "approach" and "proof." "{{w|Approach the bench}}" is a legal term meaning to have a private conversation with the judge; approach in calculus means an infinite process where a function value gets closer and closer to a {{w|Limit (mathematics)|limit}} value that it never actually reaches, reminiscent of Zeno's paradoxes. "Proof" is also ambiguous, with a different meaning in formal mathematics than in {{w|jurisprudence}}. See {{w|Proof (truth)}} and {{w|Mathematical Proof}}, for example.

{{w|Gottfried Leibniz}} is the co-inventor of {{w|calculus}} (along with Isaac Newton; see [[626: Newton and Leibniz]]). If Leibniz were to testify in this imaginary trial, he might argue that calculus invalidates Zeno's paradoxes, because the moving arrow has a different velocity than a stationary one (the function describing the motion has a nonzero derivative at the point), and the {{w|infinite series}} in the dichotomy paradox has a finite sum. Both Zeno and calculus assume a continuous, infinitely divisible, ideal {{w|spacetime}} (as does {{w|quantum mechanics}}); a different solution would be available if spacetime turns out to be discrete. However, Zeno is arguably not concerned with actually calculating the correct answer. In the real world, Zeno can be trivially disproven simply by moving and reaching a desired target (it is said that Diogenes the Cynic reacted to the paradox by wordlessly walking to a destination, to demonstrate his contempt for it). It remains a question of debate whether a mathematical approach addresses the central points in Zeno's arguments.

[[994: Advent Calendar]] is also about Zeno.

==Transcript==
:Zeno: My client couldn't have killed anyone with this arrow, and I can ''prove'' it!
:Judge: I'd like to examine your proof, Zeno. You may approach the bench.
:Zeno: —But never reach it!

{{comic discussion}}
[[Category:Philosophy]]
[[Category:Math]]
[[Category:Multiple Cueballs]]