Dead Sea shoreline, 429 metres below sea level.
This weekend, a friend asked me if the rise in the oceans could be drained off into the world’s below-sea-level depressions. Could rising ocean waters be diverted to fill the Dead Sea and Death Valley Depressions, for example? It seems a creative solution. Instead of flooding the Maldives, Piazza San Marco, and south Florida, the expected ocean level rise could fill some of the Earth’s less inhabited wastelands instead.
At this moment, I don’t want to debate the idea of climate change and its impact on sea level. I think the evidence is substantial that Arctic ice and mountain glaciers are disappearing and the melt water is reaching the sea. But this may ultimately be a thousand-year-long melting blip before the return of another ice age. I don’t know. What I’d rather do today is simply try to put some numbers on the innocent question: Would it be practical to relieve coastal flooding by filling land-locked places that are below sea level?
Solving this question is relatively trivial and the answer may surprise you. Using Global Mapper, I loaded a digital elevation overlay, then contoured the outlines of many of the planet’s below-sea-level depressions. There are 49 countries containing land with elevations that are below sea level so there are a number of places to hide future flood waters. Some depressions are small and deep (including Turfan, China and Akdzhakaya, Turkmenistan) while others are broad and shallow. I measured these and the areas of subsea regions such as the Dead Sea and Afar depressions, the gigantic Qattar low elevation desert, Death Valley, Salton Trough, and others. Then I estimated the volume of water these basins could hold.
Areal extent of sub-sea-level Salton Depression, California.
The Dead Sea coastline, as you undoubtedly know, is the lowest dry land on the planet – it is about 429 metres below sea level. The “sea” is within a 5,000 square kilometre depression, much of which is shallower than 300 metres. Nevertheless, the Dead Sea Depression, flooded with sea water, could hold 1,500 cubic kilometres of water. Filling the sink, however, would eliminate some rather nice olive groves and would submerge important historical sites – including Jericho, a town of 20,000 and perhaps the oldest community on Earth.
North Africa’s Qattar Depression – a vast desert below sea level.
Other desert depressions are less populated, so (other than some camel operators) who really cares if they get wet? In particular, there’s the vast north Africa Qattar Depression which covers about 25,000 square kilometres. If we include other low Saharan regions in Tunisia, Libya, and Algeria, we may find as much as 50,000 square kilometres of sand sit below sea level. One may argue that this territory is less attractive than the Dead Sea or Death Valley which we have also slated for drowning, but the enormous Sahara tracts are not deep. Much is barely a single meter below sea level. So, despite being vast in area, the volume of water potentially held is less than a fully inundated Dead Sea.
Continuing around the world, we may be able to siphon 7,500 cubic kilometres of water from the ocean, pumping the sea’s brine into the planet’s various depressions. That is a huge quantity of sea water and should take the pressure off the folks in Miami. But, unfortunately, it turns out to be a trivial drop in the proverbial bucket.
The Earth is a big place. The oceans cover 360 million square kilometres. A meter of sea level rise is a volume 50 times greater than all of the depressions that are below sea level in the world. Climate scientists tell us that the ocean’s waters are presently rising at a rate of about 3 millimetres a year, or 3 centimetres a decade. In just ten years, all of those hypothetical sinks would be full and the waters will still be rising. Because the actual rate of melting is increasing through an amplifying feedback loop, we are told to expect about a meter of sea level increase in the next hundred years or so. It will likely take several centuries for all the world’s ice to melt. By then, the oceans will be 75 metres deeper than they are today.
The bottom line? Flooding Jericho will not save Miami’s Fontainebleau. Nor, if seas rise unabated, will we save Venice, New York, nor the homes of three billion of the planet’s seaside dwellers. Rather than attempting to hide the meltwater, it appears that we need to think of another plan to do something about the impending flood.
The Mountain Mystery 
Pingback: Hiding Rising Seas in Sunken Deserts | Not So Solid Earth
Reblogged this on Primate's Progress and commented:
Would the depressions below sea level in 49 countries provide a way to accommodate rising sea levels? No.
Human folly is the root source of our greatest problems (actually, that’s as true and useless as saying that oxygen is the root source of forest fires). Creationism, on which I’ve written so much, is one manifestation; global warming denial another, and much more serious in its probable effects.
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Thanks for your comment, Paul. The question itself was interesting to me because it showed how people often think about the Earth: Maybe we could just hide our problems in some sink hole somewhere. Alas, that seems to be a common attitude.
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Filling desert basins with ocean water with the goal of lowering rising ocean levels and reversing global warming may work because the presence of these inland seas would help lower temperatures in some of the hottest places on earth. If lake Eyre in Australia were filled with ocean water from the Coral Sea, hydro electric power could be produced from the water’s journey into the lake and out to the South Sea, and Australia would have an inland sea larger than Germany. The Gobi desert and western China have about five huge depressions which could be filled with ocean water and connected to each other by canals streaching from China’s east coast to the Aral and Caspian Seas. The pressence of these seas would eliminate dust storms and lessen the severity of droughts in central Asia and in Northern China. Filling Africa’s Chad depression with water from the Atlantic would dramatically lower local temperatues, increase rainfall, and provide a huge fishery for local people. -These thoughts of mine are all dreams of coarse. But, some dreams become reality. If global warming is real, -if oceans are steadilly rising, we must attempt to reverse the proccess. To stand by and allow Holland, Bangladesh, London, Beijing, New York, Singapore, Lagos, and Rio to be flooded without attempting to do what I have proposed seems unwise. Filling the world’s desert basins with water may buy us the time we need to transition from coal and petrolium to cleaner and more sustainable energy sources (thorium reactors, algeatech, energy towers, tidal power, ect..).
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Thanks, Jorge – you have certainly given this idea a lot of thought! Thanks for the interesting points. My story, of course, was written in answer to a friend’s question and was not intended as a serious suggestion to slow the rising sea level. But your idea of flooding deserts to alter warming is intriguing.
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This is a very interesting topic, It once came to my mind back in 1999 When I first heard of sea level rise. I Was a teenager. Now I know is a really bad idea but its interesting to discuss why.
In my opinión It would requiere the largest construction project Ever. We re talking about extracting thousands of sq kilometers of sand/rock to get to those places
How much money would this mega project cost? Water from oceans cant just be pumped in deserts with a 60” Pipe
Havnt seen anyone talking about the weight we would Put on earths crust. It would be larger that all the dams in the world combined.
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For me the Aral sea is a great example, surely pumping sea water into that cannot do any damage, there is currently no water and once there is water then the fish arrive and that creates jobs and so on. They can divert all the fresh water they want but the sea itself would be fine if it only had salt water. I bet if you asked any Aral resident they would be happy to have any water!!
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I’m not a fan of geo-reconstruction, but you have a point. People wrecked the Aral and pumping in water would certainly reduce the nasty dust storms and lost fishing. I agree that the folks living nearby would probably prefer ocean water to no water in their own sea.
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another thing to consider is water diverted to deserts will drain back into the earth and evaporation will also cause levels to disapear over time, so maybe you could drain part of the ocean on regular basis
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Thanks! Interesting comment. If the water actually drained into the Earth (refreshing aquifers) then some of the water would be taken out of circulation. However, the article tells us that filling the deserts and lowlands with water won’t take care of much of the problem: “A meter of sea level rise is a volume 50 times greater than all of the depressions that are below sea level in the world.” So even with regular draining into the subsurface (which won’t necessarily occur) only a tiny portion of sealevel rise is alleviated.
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That’s why the electric bulldozers would need to clear the path, and it would cost much more money than if we had simply have dealt with this in the 1980’s. Actually, self-replicating robots would be a must for such a gigantic project. It would actually make a good soft run for the construction of a future Dyson sphere. For more info on those machines, see this Kurzgesagt video:
I’m actually optimistic about the climate crisis. Our cleanup effort is not going to be cheap, it will kill a lot of people (until we find a non-nuclear method of SRM), and how much of that we have to do is highly dependent on what we do now.
About long term sea level rise: I don’t really care. By the time this sea level rise takes place, quantum teleportation will likely be advanced enough to, for instance, swap out icebergs and small asteroids. If it isn’t, space travel will still be highly advanced and there will be plenty of demand for water on other planets, so a way will be found to bring water or ice into space.
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There is really enough land ice to raise the ocean level 75 meters? That seems like a lot. We know that sea ice melt has no impact on water level. As for pumping, we can just dig trenches to the ocean from these locations. Then we could also harness the power of the tides coming in and out of these bodies.
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Hello,
According to earth scientists (and anyone with a calculator and a head for math), a rise of 70-80 metres of sealevel will result when all land ice has melted. Harnessing tidal power is still a promising source of energy, but it’s hardly necessary to wait until the oceans rise and trenches are dug to low-lying areas. Economics are largely in place today to make this energy viable.
Ron
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You speak of flooding north Africa desert with extra water from melting ice. This desert doesn’t belong to your country and you don’t have the right to speak about it at all. you cause the climate change and you think you can decide to solve it like this. What will our people eat? You should know that our desert is being worked and can be used to produce more food to export towards land flooded countries. Why don’t you think to mobilize your country’s people to force your president to decide to reduce the co2 pollution.Think twice before deciding anything.
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Thank you for your comment. I’m sorry that this blog post was offensive to you. You are completely right, no one has the right to flood another man’s country. I was not threatening Algeria, where you live. Perhaps you noticed that I start by mentioning the Dead Sea, Death Valley, and the Salton Sea? The latter two are in America (but I don’t live in the USA). My blog post responded to a question from a friend. He asked, “Why can’t we just flood the low areas on Earth to get rid of sealevel rise?” I explain, mathematically and geographically, why this is a bad idea. But no one is serious about it – it is a joke.
I did not mention the geopolitical issues because the whole idea is nonsense. I ended the blog by writing “Rather than attempting to hide the meltwater, it appears that we need to think of another plan to do something about the impending flood.” I thought that made the story clear and the idea untenable.
By the way, I do not have a president – my country has a prime minister and my country has enacted a carbon reduction program. Has yours?
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To ad to the benefits those big lakes wil cool down the earth a little by evaporation, it wil also reduce the salt level in the oceans if this continues for a long time in the past were there also salt lakes on the planet, it will increase rainfall, a thriving fish industry, salt mining, if the temperature drops a little and the humidety rises it will benefit the inviormend all around rainfall will increase, but also snowfall, trees have a beter chance to grow and will help cooling down the earth a little more, birds will come to the areas, crops wil be easier to grow, the economy will benefit, and the struggle to survive will decrease, if this will be done the poor will benefit, but are there people, ore country’s, willing to help those in need, i don’t think so all look to there own acaunt, and not to the children of the future, and maybe it is a litle drop butt every drop helps
Simon
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I agree there could be some benefits, but you underestimate the floodings’ drawbacks in fighting global waming: The most potent greenhouse gas is water vapor – much more so than CO2, water vapor feedback renders CO2 important in the first place -, so adding evaporation will add radiative heat. The desert has a high albedo, reflecting solar radiation, as opposed to water surfaces which feature an extremely low albedo, effectively absorbing solar heat. So just like the local climate would become less extreme, global temperature rise might most probably amplify by desert flooding measures.
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Thanks for your comments, but please realize that I am not endorsing this idea. Instead, I am showing how it’s a poor and unrealistic solution to global sea rise. I appreciate your remarks about the desert v water albedo effects as they offer further evidence of the failing of such a system. Of course this doesn’t change the answer to the original question: “Could rising sea water be sequestered in below-sealevel depressions?” The answer remains that the amount of water theoretically captured in such new basins would have an insignificant impact on the metres of ocean rise that’s likely coming.
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You should have accounted for the rate of evaporation these are desserts after all and extrem ones at that it’s not a one and done their filled, they require a constant supply of water
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Besides flooding deserts (which is a great idea), I’ve read Mr. Biello’s Scientific American article about 10 Solutions for Climate Change and might have an eleventh solution https://www.scientificamerican.com/article/10-solutions-for-climate-change/. As an engineer, I usually don’t read many actual engineering solutions on climate change. Typically, articles read as a “dooms-day scenarios” to climate change. But Mr., Biello’s article was very thought provoking and innovative.
Here is a new solution. Greenland is a big contributor to ice melt and thus sea rise. NASA has determined a mega-canyon under Greenland’s ice https://en.wikipedia.org/wiki/Greenland%27s_Grand_Canyon. It is approximately 50% bigger than the Grand Canyon, but not as deep. This mega-canyon’s bottom is below current sea level and flows north on Greenland. It is the largest canyon on earth. What if a Hoover Dam like structure is built near the mouth of this canyon? What if the ice melt was contained within this mega-canyon? Would it not help reduce sea level rise? Assuming the earth warms up to the point of Greenland’s total ice melt, this canyon would be the largest fresh water lake in the world. Hotels and developers could make it a seasonal vacation destination.
This dam would cost billions of dollars, but what is the cost of building sea walls and other barriers around cities when sea levels rise around the world? What is the cost of moving people away from coastal cities? What is the cost to insurance companies for flood damage or governments paying for infrastructure costs?
Thoughts?
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Thanks for the comments and links. My blog posting does not actually advocate flooding anything – partly because of the rights of those people who would be flooded but mostly because I calculated that it won’t make much difference in reducing more than a couple centimetres of likely worldwide sea level rise. In my post, I am answering someone’s “what if…” question, but I’m also trying to point out that we are in an intractable situation if we rely on mechanical solutions.
However, I wasn’t aware of the Greenland Canyon. As described in the Greenland’s Grand Canyon link which you provided, it is 750 km long, 10 km wide, and almost 1 km deep. That would hold a heck of a lot of water. 7,500 cubic kilometres, in fact. However, even this would only lower global sea level by just 2 centimetres. We’re going to need to do something else. Like buy property at a higher elevation for 3 billion displaced people. Thanks for commenting and thanks again for those related links.
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Thank you for all your comments over an argument i was thinking about. I was wondering: would the albedo be less if all the Sahara should be covered with trees? The increased evaporation from flooded depressions could bring some rainfall over sahara and start the creation of a green area that transform CO2 into wood? I don’t think water vapor is a problem as it become rainfall according to temperature so it could be less then now if we stop local warming.
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Thanks, I suppose that the ‘greening’ of the Sahara would have a moderating effect. It probably would do little globally, but would certainly have a nice local imapct.
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During my whole life , I’ve never heard such stupid suggestions It’s deceiving mainly when they come from scientists.You prefer easy solutions without caring about the consequences. During the 19th century French colonialists thought of creating an internal sea by passing sea water from the Tunisian Chott which is under the sea level. But they preferred to abandon the project after having studied the long term consequence, which is not your case.The high temperatures will cause rapid evaporation of water leaving high concentrated salt lands pteventing any greening or life.Moreover winds will spread salty droplets on other lands killing everything around.
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Thank you for sharing your thoughts. However, had you actually read the piece before commenting, you would know that this blog post does not endorse the idea. It’s an exercise in creative thinking and the blog actually shows how this won’t work. Too bad you didn’t read before commenting. By the way, if it’s true that “During my whole life, I’ve never heard such stupid suggestions” you have certainly lived a charmed life. Or, you haven’t been paying attention to anything going on around you.
You may also want to rethink your idea that “…winds will spread salty droplets on other lands killing everything around.” – Killing everything is a rather brutal assertion. If this were true, there wouldn’t be any form of life at any seasides. No mangroves, no sea grapes, no palm-studded islands. Nothing. Anyway, I had a good laugh from your comment so I’m sharing it with everyone. Thanks again.
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I’m not an expert, not even close. But I think while filling those sinks, we would also be filling subterranean stream channels. Therefore the amount of water that we would be reducing from oceans would be more.
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Possibly true. This shows that this is a bad idea. But if subterranean streams are filled with salt water, it’s even a worse idea than I wrote.
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