Editing 2889: Greenhouse Effect

{{comic
| number    = 2889
| date      = February 2, 2024
| title     = Greenhouse Effect
| image     = greenhouse_effect_2x.png
| imagesize = 740x315px
| noexpand  = true
| titletext = Once he had the answer, Arrhenius complained to his friends that he'd "wasted over a full year" doing tedious calculations by hand about "so trifling a matter" as hypothetical CO2 concentrations in far-off eras (quoted in Crawford, 1997).
}}

==Explanation==

This comic has [[:Category:Climate change|climate change as its topic, a recurring theme]] on xkcd. There is no 'joke' <em>per se</em>, just a wry (and serious) observation on the timeline of climate change, and our understanding of it. The fact in question here is when science became aware of anthropogenic global warming and its primary cause.

The comic depicts a timeline with three events:
* The introduction of the {{w|Watt steam engine}} in 1776. The comic takes it as the start of the {{w|Industrial Revolution}}, and the event that most directly ushered in the boom of fossil fuels' burning.
* [https://en.wikisource.org/wiki/On_the_Influence_of_Carbonic_Acid_in_the_Air_upon_the_Temperature_of_the_Ground The first quantitative prediction] of the {{w|greenhouse effect}} by {{w|Svante Arrhenius}} in January and April 1896 (that doubling CO<sub>2</sub> concentration would increase mean temperature by 5 to 6 °C, depending on latitude). Arrhenius drew on and included a summary of {{w|Arvid Högbom}}'s 1894 Swedish article, which dealt with carbon cycle over geological periods and first estimated annual global carbon emissions.
* The present day, early 2024.

As the caption points out, less time elapsed between the start of the Industrial Revolution and the work by Arrhenius, than has elapsed since then. Some present-day climate discussions may cite [https://onlinelibrary.wiley.com/doi/abs/10.1111/j.2153-3490.1957.tb01849.x a 1957 paper by Revell and Seuss] as "the starting point" for modern inquiries into global warming. While it was more advanced and detailed, the comic notes "we figured out the greenhouse effect" 61 years prior; see both [https://folk.universitetetioslo.no/roberan/t/EarlyEstimates1.shtml Robbie 2018] and even longer {{w|History of climate change science}} which includes earlier, qualitative works.

The implication, consistent with other [[:Category:Climate change|climate change themed xkcd comics]], is that humans have taken insufficient action to stop global warming despite knowing about it for more than a century, and understanding, at least intellectually, the consequences of inaction.

The title text portrays Arrhenius as dismissive of his work. A reading of the reference cited (page 8 in [https://courses.seas.harvard.edu/climate/eli/Courses/EPS281r/Sources/Greenhouse-effect/Arrhenius/3-optional-Crawford-1997.pdf Crawford 1997]: 'Writing to a friend at the end of [1895], he found it "unbelievable that so trifling a matter has cost me a full year".') suggests instead that Arrhenius was complaining about the unanticipated difficulty of answering what he thought initially was a simple question, about the historical (geological time) connection between carbon dioxide concentrations and global temperature. Per this reading, Arrhenius's complaint was about the work required to achieve the result, <em>not</em> about the significance of the result. His interpretation of the significance, though, differed from today's (page 11 in Crawford 1997): "[Global warming will] allow our descendants, even if they only be those of a distant future [estimating the doubling time as 500 years], to live under a warmer sky and in a less harsh environment than we were granted".

==Transcript==
:[At the top of the comic a timeline is shown as a long line. It has three dots, one at each end a bit inside the end of the line and one close to the middle Each dot has a gray curved line going up to it from below. Below the end of these lines a year is given. And beneath the year is a caption. Above the time line are two gray double arrows going from three gray lines above each of the three dots. The lines are broken in the middle where a label is written.]

:[Label of arrow that spans from first to second dot:]
:120 years

:[Label of arrow that spans from second to third dot:]
:128 years

:[Label for the first dot:]
:'''1776'''
:James Watt develops a steam engine that helps kick off the Industrial Revolution

:[Label for the second dot:]
:'''1896'''
:Arvid Högbom and Svante Arrhenius note that industrial activity is adding CO<sub>2</sub> to the atmosphere, and calculate how much the Earth will heat up if the CO<sub>2</sub> concentration doubles. Their answer closely matches modern estimates.

:[Label for the third dot:]
:'''2024'''
:Today

:[Caption below the panel:]
:We figured out the greenhouse effect closer to the start of the Industrial Revolution than to today.

==References==
<references/>

{{comic discussion}}

[[Category:Climate change]]
[[Category:Timelines]]
[[Category:Comics featuring real people]]