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I have been reading the discussion about pumping sea water into the desert for purposes of irrigation and changing the dry climate of that area, but what about to just purely offset the rising sea levels? Could pumping ocean water (with solar power) north of Malibu California into the dry areas help with coastline erosion and put water into the desert as a secondary but not primary benefit? I am a completely non-scientific person who just happens to have an interest in coastal erosion so I welcome all your educated thoughts on this. Ideally it would be done in all the deserts globally to have a coordinated effort. Think of the infrastructure jobs in places like Africa. It would require a “world bank” initiative to create the funds to do this but as a global coordinated effort it may be required as part of planet rehabilitation. Yes I said “create” the funds, ie “print money” which would have a slightly inflationary effect on world economies but would mostly “inflate” depressed economies through wealth redistribution since these economies would likely be the major supply of labor. Like we see in Canada when the people from poor fishing towns went to work on the pipelines and brought cash back home.

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This is no an answer per se, just a back-of-the-envelope calculation for fun.

Lifting 1 kg (one litre) of water up a height of 1 meter uses 9.8 (let's say 10) joules of energy.

Let's say you want to lower the sea level by 1 meter. You need to pump 3.6e17 litres (3.6e14 m2 of ocean area = 3.6e14 m3 to pump * 1000 for litre conversion).

Let's say you want to lift this water up a height of at least 10 meters, so it doesn't go right back into the ocean but rather stays behind some kind of dike. We're already at 3.6e18 J of energy. That's 1e15 Wh, or 1000 TWh. That's more than what the 20 largest power stations combined produce in a year.

This also assumes an ideal, 100 % efficient pump (no energy loss)...

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  • $\begingroup$ Ah, so there'd be a selective pressure towards quick infantile growth, and/or the development of fins, eh ... nature finds a way ... sorry, couldn't resist :-) $\endgroup$ – user18607 Jan 9 at 20:43
  • $\begingroup$ @ebv: No, just a migration to the non-flat parts of California :-) But with California, there are ways that don't involve ongoing energy. Most of the rivers start in the Sierra Nevada. Just drill tunnels at about the 5000 ft level, send the water over to Nevada, and fill the Great Basin. (And further south, Independence Lake, which might drain into Death Valley...) Then build a dam at Carquinez Strait en.wikipedia.org/wiki/Carquinez_Strait and flood the Sacramento and San Joaquin valleys. $\endgroup$ – jamesqf Jan 10 at 5:31
  • $\begingroup$ @jamesqf: Hehe, to take the joke further, the richer ones migrate and build new palaces on the hilltops in the last natural reserves, the poorer ones drown. Example: Jakarta. (I am not scoffing at you, you have my respect ! Just trying to be funny ...) $\endgroup$ – user18607 Jan 10 at 9:06
  • $\begingroup$ @Fred How can lowering all the worlds oceans by 1 metre and dumping it into California possibly only flood it by 0.9 metre? That can't be right, you're missing some zeroes. The oceans cover 3.6e14m², California covers 4.24e11, so it would be covered by around 840 metre in my back-of-the-envelope calculation... $\endgroup$ – gerrit Jan 10 at 11:17
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    $\begingroup$ @gerrit - California, like the Tardis, is bigger on the inside. $\endgroup$ – David Hammen Jan 10 at 11:23
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Yes, it could reduce sea level rise, but it would be no good for irrigation. Many deserts, like the Aral Sea and Death Valley, are below sea level. This means you would not need to use energy to pump the water, but could use the siphon principle. Some people say that even if you filled all these low-lying deserts with sea water, it would not do much to lower sea level. However, it would have many other beneficial effects, especially in the Aral Sea. It would greatly improve marine transport, create new fisheries, prevent the present salt desert being blown onto agricultural land, and quite likely change the climate so there would be more precipitation.

Another way to reduce sea level, though it would be only by a tiny amount, would be to build more dams. Deprived of the held-back rain water, the sea level would reduce a little if enough rainwater was prevented from reaching the sea. The dams would produce carbon neutral power, create fisheries and be used for irrigation. On the other hand, if the proposed dams on the Nile are anything to go by, they also have the potential to start wars unless they are sited with great care and good international diplomacy and cooperation.

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    $\begingroup$ Well, one would need a many hundreds if not 1000km long frictionless pipe and dam construction without greenhouse gas emission. Doesn't sound like a plan ... $\endgroup$ – user18607 Jan 9 at 18:35
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    $\begingroup$ The energy needed to pump the water would be enormous. Check again sea levels. $\endgroup$ – user18607 Jan 9 at 18:48
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    $\begingroup$ It is not personal. You're just violating the rules of citing. SE explicitly encourages to downvote unsupported posts. Caspian is below, Aral above msl, right ? To get water from C to A, we must pump it up, not let it pour down. Or have i misunderstood ? $\endgroup$ – user18607 Jan 9 at 18:57
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    $\begingroup$ i doubt much more to create a lagoon on those basins wouls afect a lot sea level. Even a big surface, the new sea wouldn't bee very deep $\endgroup$ – Universal_learner Jan 9 at 19:29
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    $\begingroup$ A few meters, yes. The Aral Sea is more of a pan than a pot. I am still hopeful that @MichaelWalsby actually researches an answer before posting. I'll be the first to upvote (if fast enough). $\endgroup$ – user18607 Jan 9 at 19:38

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