Editing 2859: Oceanography Gift

{{comic
| number    = 2859
| date      = November 24, 2023
| title     = Oceanography Gift
| image     = oceanography_gift_2x.png
| imagesize = 740x272px
| noexpand  = true
| titletext = 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==
In this comic, [[Randall]] seems inspired by the timing of {{w|ocean current}}s, much as he has previously been with [[2805: Global Atmospheric Circulation|air currents]], although he may even have already considered some of the technicalities [[1675: Message in a Bottle|prior to that]]. As supporting evidence, he provides a DOI reference to a 2016 Jönsson & Watson open-access article in Nature Communications, '[https://www.nature.com/articles/ncomms11239 The timescales of global surface-ocean connectivity]'.This would be extremely impractical, since in ten years, it's possible that you and the recipient broke connections, or one of you (or both of you) passed away. If these scenarios are not the case, ten years is an awfully long time to wait for a present.

In this specific (fictional) example, the water dumped into the ocean today will take ten years to circulate round to the depicted neighbouring coastline (wherever that is). Which implies significant planning ahead is necessary before posting water to someone. And a lot of presumption about the lack of any other dispersal/dilution, or that some degree of fungibility is acceptable, so long as it is ''{{w|Ship of Theseus|philosophically}}'' the same group of molecules involved. Of course, some of the water molecules may take a short-cut by being evaporated then precipitated closer to the delivery site.

The title text mentions that "same-ocean delivery" may only take a few years, as the coast lines are in the same general body of circulating water, and doesn't have to pass around large obstacles (like continents) or through small gaps (straits). But if you wish delivery from {{w|Weddell Sea}} it may take decades. The Weddell sea lies near the {{w|Antarctic Peninsula}}, part of the {{w|Southern Ocean}} whose circulation can be considered largely isolated from the neighbouring bodies of water by the {{w|Antarctic Circumpolar Current}}. In particular, that area contains the {{w|Weddell Gyre}} one of the two {{w|ocean gyre}}s in that area.

The title text also mentions {{w|inland sea}}s, which can be generalised as bodies of water that are very large in area but either completely surrounded by dry land or connected to an ocean only by a river or a strait. He mentions the {{w|Mediterranean Sea}} which is only connected to the {{w|Atlantic Ocean}} through the narrow {{w|Strait of Gibraltar}}; the intention of the title text is to suggest that water molecules dumped in an ocean would not get to appear in such a sea (except by {{w|evaporation}} and re{{w|precipitation}}) into its catchment area) and thus they can only ever circulate back to the dumping point (deemed 'undeliverable'). 

In reality, the Mediterranean Sea is not completely cut off from the main oceans and surface currents actually do reach into and around the Mediterranean. The natural loss from evaporation is not fully compensated for by the inflow of the incident rivers from southern Europe, North Africa and Asia, directly or via other attached bodies of water (e.g. the Black Sea). The movement of water also involves the deeper Levantine Intermediate Waters layer (a subsurface current) which exits via Gibraltar and helps to further draw current inwards at the surface level.  As such, except for a limited amount of water which reverses direction within the extreme western end the Mediterranean, it is more true to say that ''surface'' currents cannot actually transport water from within the sea outwards into the Atlantic (and beyond).  (This explanation ignores flow through the Suez Canal.)

The {{w|Caspian Sea}} is a real inland sea that has no outlet to any oceans and only inlets from rivers, one of many [[2325: Endorheic Basin|endorheic basins]] that are also lakes, and thus trivially isolated from all other maritime currents.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.|Probably still improvable}}

:[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 <!-- Written like this in response to the possibility that Randall is trolling us, or causing us inconvenience, by using our "transscript format for a description" actually *in* the literal text... -->

:[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.

{{comic discussion}}

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