2859: Oceanography Gift

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Oceanography Gift

Title text: Shipping times vary. Same-ocean delivery may only take a few years, but delivery from the Weddell Sea in Antarctica may take multiple decades, and molecules meant for inland seas like the Mediterranean may be returned as undeliverable by surface currents.

Explanation

This explanation may be incomplete or incorrect: Created ten years ago by a WATER CURRENT - Please change this comment when editing this page. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

In this comic, Randall seems inspired by the timing of ocean currents, much as he has previously been with air currents, although he may even have already considered some of the technicalities prior to that.

The DOI Jönsson & Watson reference is to a 2016 open-access article in Nature Communications 'The timescales of global surface-ocean connectivity'.

The idea here is that water dumped into the ocean today will take ten years to circulate round to the next coastline (wherever that is). So you can plan ahead before posting water to someone...

The title text mentions that if it is "Same-ocean delivery" it may only take a few years as the coast lines are in the same general body of water, and doesn't have to pass around large obstacles like continents or through small gaps.

But if you wish delivery from Weddell Sea it may take decades. This is not only because it lies near the Antarctic Peninsula. You might wish delivery to a nearby oceans coast... But also because it contains the Weddell Gyre one of the two gyres that exist within the Southern Ocean. An Ocean gyre is any large system of circulating ocean surface currents. So any water dropped there would likely end up circling there for much longer than water dropped in any particular other part of an ocean where there is no gyre nearby. For certain it has been Randall's intention that we should all end up reading about Ocean gyre.

The title text also mentions Inland seas, which is bodies of water that are very large in area but is either completely surrounded by dry land or connected to an ocean only by a river or a strait. He mentions the Mediterranean Sea which is only connected to the Atlantic Ocean through the narrow Strait of Gibraltar; therefore, water molecules dumped in one ocean would not get to those oceans (except perhaps by evaporation and precipitation). And thus they are returend to sender as undeliverable.

The Mediterranean Sea is not completely cut off from the main oceans and the surface current is actually going into the Mediterranean Sea, as the heavier and more salty water in the inland sea causes the water to sink below the water of the Atlantic sea. So the outflow from the sea is far beneath the surface. So actually it would be water dumped in the Mediterranean Sea that would never leave the ocean as surface water!

The Caspian Sea is a real inland sea that has no outlet to any oceans and only inlet from rivers.

Transcript

This transcript is incomplete. Please help editing it! Thanks.

[Cueball and Megan are standing thigh deep, at either edge of a stretch of water between two steep but walkable shorelines.]

[Cueball, at the left, is apparently opening bottles of water and pouring them into the sea while recording himself.]

Cueball: Happy birthday!

Cueball: I got you these water molecules.

[Sound effects:] (click) (pour)

[The water between has a morass of short swirling arrows indicating movement. In the air above this there is a square-bracketted 'label']

[Label:] 10 years pass

[Megan, at the right, is dipping bottles into the water to fill them]

Megan: Aww, thank you!

[Sound effect:] (scoop)

[Text below comic:]

Global surface ocean connectivity times are ≤10 years (Jönsson & Watson, 2016, DOI:10.1038/ncomms11239), so if you're willing to plan ahead, you can pour water into the ocean while wishing someone a happy birthday, and then in 10 years let them know they can pick up their gift at the nearest coastline.

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Discussion

The explanation for inland seas is incorrect. What Randall refers to is that with some (or many) of them, the surface currents work against letting any water flow in, because those currents flow outward. Thus, water poured into the Atlantic won't enter the Mediterranean, but water poured into the Med will move outward and then join the general ocean exchange. What the explanation says does apply to (for instance) the Dead Sea. Of course, water molecules added to that have a high chance of evaporation, which would then get them into the global circulation anyway. 172.71.98.97 (talk) 07:04, 25 November 2023 (please sign your comments with ~~~~)

This is incorrect anyway, since the Mediterranean has a net inflow of water from the Atlantic (inflow from its rivers can't make up for evaporation). 172.70.38.34 08:20, 25 November 2023 (UTC)

I would not have called the Med an "inland sea", either.

Though I haven't read the main article/its history, since I put the very first paragraph there and invited others to add more. I presume someone took that literally (like Dead, Aral, Caspian or Salton, each with their own characteristics) rather than with the perhaps rather over-broad definition of having a single relatively narrow 'neck' connection.

But the caveat in the Title Text of undeliverable by surface waters does apply, depending upon where you're sampling, as the Levantine sink of water takes inflowing water (that hasn't reversed around Corsica and gone straight back out) and feeds it round to the depths (and out again into the Atlantic) to a large degree. If you're relying on the 2D circulation, you lose such connectivity through the depths as well as it attaining atmospheric height...

i.e. complex, and I think Randall's wording is not perfect. And yet to see if I can go back and improve/correct/support the Explanation. 172.71.178.134 18:47, 25 November 2023 (UTC)

...and, re: the later edit about the Suez, yes. That too. Meant to consider it, in my re-edit, but forgot to finish checking which way the flow was (or tended to be). Good catch, though. 172.71.94.193 15:06, 26 November 2023 (UTC)

I am not inclined to call the Mediterranean an "inland sea" either, at first thought... but upon inspection, perhaps only because Europe and Africa are separate continents, which makes it feel less "enclosed" and more of a "border", which is not a very good reason. Terdragontra (talk) 20:23, 13 January 2024 (UTC)

Well, (very-pre-)historically, it was the Tethys Ocean, before the continents started to close up like they have done. 172.69.79.139 21:09, 13 January 2024 (UTC)

Randall says that molecules intended for the Med may be returned as undeliverable - not that they will. I would read that to mean that they're more likely to end up back where they started than they are to make it to a destination in the Med, in which case the current explanation is a bit off base.172.71.242.37 09:26, 27 November 2023 (UTC)

I'm not sure the overall premise is accurate; the paper is dependent on very low probability pathways, using the ability of algae to reproduce in those regions to give billions of chances of hitting those difficult pathways. The water in the bottle doesn't reproduce. 172.69.194.70 (talk) 09:51, 27 November 2023 (please sign your comments with ~~~~)

<mumble mumble>...homeopathy...</mumble mumble> 172.71.178.32 12:00, 27 November 2023 (UTC)