Seaflooding | Hacker News Reader

Seaflooding

unchartedterritories.tomaspueyo.com

322 pointsdeegles138 comments

This feels like an over-simplification of the benefits. I have yet to be convinced that filling an area with salted water, which by evaporating will only increase the salt concentration, can host a thriving ecosystem.

I'm also having trouble buying the argument that to lower the salt concentration we can extract it and sell the salt. Sure we can, but are talking about the same scale here?

Moreover, it may look like a hostile place, but I'm sure that in all the examples given there are populations there, maybe nomadic, and there are organisms that live there.

Finally, I find it interesting than when illustrating the Quattara seat, the author has added green around it, but I see no reason for that greening to be there at all when a few hundred kilometres north on the border of the current Mediterranean sea there's nothing. After all, same region, roughly same altitude, same water, but even higher salt concentration.

So yeah, I love the futurism aspect of the article, it makes me dream of a techno-solution, but I remain unconvinced though I'd love to be wrong.

> I'm also having trouble buying the argument that to lower the salt concentration we can extract it and sell the salt. Sure we can, but are talking about the same scale here?

Besides, this is not economical.

> I see no reason for that greening to be there at all when a few hundred kilometres north on the border of the current Mediterranean sea there's nothing.

Northern Africa is dry now, but as the north warms up this may actually change (https://www.forbes.com/sites/trevornace/2017/11/09/northern-...).

> I'm sure that in all the examples given there are populations there

Which should benefit from this the most.

> there are organisms that live there.

I just don't get the argument. Are you worried about some organisms in one of the least hospitable places? Some organisms that may live there and thrive in dry salt, but not if it was wet? What makes you specifically worried about those organisms that you dislike the potential for more and more diverse organisms if it was a sea instead of salty sand?

>Which should benefit from this the most.

But that's making an assumption about their desire, maybe they don't love the idea of being displaced and having to have another activity (tourism or whatever) in order to live.

Regarding the organisms living there, my point is we don't know what effect getting rid of such an ecosystem could have in the global scale. Maybe whatever bacteria / insect / small mammal that manages to survive there is useful for a species of bird that stops there on their way to another reproduction site. We can look at it and think by filling it with water it will be "better", whatever better means, but there are serious unknown unknowns that we can't take into account.

Exactly - history is littered with unintended consequences.

The ship for "maybe we should not do something lest we disrupt the ecosystem with unintended consequences" has sailed.

The solution to negative unintended consequences is not to trigger more and hope that the next lot are positive.

Maybe a solution to unintended negative consequences from destructive activities that never cared about environmental impact until too late is more so a constructive project with intended positive consequences and specific environmental goals and less so the default alternative of "keep doing those destructive projects as before and stall anything else"

> there are serious unknown unknowns that we can't take into account.

We can model stuff. Also we don't find out if we don't try.

I just don't get how we are fine with causing constant large-scale intentional harm to environment for industrial purposes even as there were so many unintended consequences, but when considering a major project specifically aimed to benefit our environment and long-term humanity it's instantly the apathetic "oh but what if?".

Plus consider the amount of free clean water energy and positive uses of that as a result of this project.

People constantly overestimate the benefits and underestimate the harms on projects like this. Where I live we made it a point to dam up a lot of rivers to get hydroelectric power, but the dams prevented fish in the area from returning home to spawn, weakening our fisheries. And in the end the dams don’t produce that much power.

All projects like that are done for money or energy first though. We know they all come with possible environmental damage and all they do is try to mitigate it. These projects keep being done and we don't bat an eye.

This is different in that it has environmental improvements as goals. Lower sea levels a bit, enrich local ecosystem, etc. So it's a bit sad that when it comes to projects like there is always paralysis but not when we just want more stuff.

Part of it is just the audience. Your average HN comment section would likely fiercely debate the creation of crosswalks, curb cuts and other common sense improvements (though that may be true of the population at large).

If the things you felt like dont receive enough attention were available for this level of public scrutiny well, I think you can rest assured it would receive it.

Because even industrial pollution at a modern scale is small potatoes compared to the possible consequences of honest-to-god intentional geoengineering. The risks here are in a completely different league.

We recently found out that the Amazon rain forest depends on winds that carry nutrients from the Bodele depression [1]. The Amazon rainforest is nutrient limited by the phosphorus it gets from the other side of the planet. Obviously the depression is way above sea level and isn’t at risk from artificial flooding in the northern sahara, but that should illustrate the scale of the consequences we’re dealing with: if we fuck up even a little bit, it could mean ecosystem collapse in the Mediterranean or beyond.

[1] https://earthobservatory.nasa.gov/images/7279/bodele-depress...

I always find it disappointing to see how little evaporation adds to the local greening (also see the boarders of Red Sea)

Well the Red Sea Coast has plenty of small plants, just no forests, large grasslands, etc... due to local climate.

It's probably unlikely for a verdant grassland to pop up next to the Qatta depression, but a lot of small plants I can believe.

[1] argues a crucial component of greening is trees "pumping" water from the oceans inland and creating nutritious soil. Otherwise evaporated water is simply blown away by the wind. I'm sure other local terrain (e.g., mountains) play a part in locally retaining evaporated water and creating conditions for rain.

[1] The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from A Secret World by Peter Wohlleben.

It is claimed that a lack of trees leads to a lack of rain (leading to a lack of trees)

https://www.theguardian.com/environment/2021/mar/20/our-bigg...

Well given that a fair bit of the Netherlands was made this way, I would think it's not impossible to make it usable land.

The Netherlands does not sit in a dry arid area though. When they reclaimed / drained it, it became like the areas near it.

Pretty sure that none of the Netherlands were created by flooding large depressions in a desert. Quiet the opposite, in fact.

I think tidal canals would be the better option than pipelines. Dig channels deep and wide enough that the water of the seas actually mingle, letting dissolved salts spread out into the wider ocean.

With quite a bit of extra digging this could get us an alternative to the Suez Canal which I believe many countries would be interested in and would strengthen global trade.

They already added lanes to the suez canal and I imagine it'd be way more cost effective to keep expanding those as needed.

There is a political advantage not to be solely depending on Egypt.

For that "deep and wide enough" to work out, just how deep and wide would the canal need to be?

Such mingling happens at the Dardanelles - but it's half a mile or so wide, and ~180 feet deep.

https://en.wikipedia.org/wiki/Dardanelles

70% of the planet is filled with salted water, which are thriving ecosystems.

Is there any reason I'm missing why expanding the ocean won't just give us more ocean?

That's a fair point, I only had a land ecosystem in mind when writing it, sure there would probably be plenty of sea life in there.

I think most of the oceans are a barren wasteland.

That said, as a shallow and, at least at first, nutrient rich part of the ocean it could be a flourishing part of it. But if it’s filled via underground pipe, it’ll be isolated from sources of ocean life.

    I think most of the oceans are a barren wasteland.

This is as far as I know, incorrect. I'm not sure why you think it would be true. Oceans, aside from areas like the Dead Sea are some of the most vibrant and life filled ecosystems we have. Even at the most crushing depths far from the sun there are entire ecosystems on the ocean floor.

From articles like this one: https://edu.rsc.org/feature/iron-ocean-seeding/2020176.artic...

Could be wrong.

But as you say: except for the dead sea.

In my mind, these new seas would have a steady influx of salt water, but only sweet water would evaporate out of them. And since I don't see the mechanism by which salt would get sequestered or removed from these bassins, I'd also guest their salt concentration would rise quite quickly.

Of course, it might still be interesting to have a huge water surface in the area that effectively serves as a rain generator, but it might not be the same thriving ecosystem we imagine when we say "ocean".

The Dead Sea is a lake, which is why it's dead.

The GP is technically correct. By volume much of the ocean is practically a wasteland because of the oxygen minimum zone [1]. A few animals like vampire squid are adapted to this zone but for the most part, the vast majority of ocean life is found in the top and bottom most layers.

[1] https://en.wikipedia.org/wiki/Oxygen_minimum_zone

Depends on whether the rate of salt extraction is precisely equal to the inflow over the long term. The Great Salt Lake is extremely salty and basically only two species can live in it: brine shrimp and brine flies. With about the corresponding level of "tourism" you'd expect.

And that is with industrial levels of salt harvesting. Would we expect the salt harvesting of these inland seas to be equal to or greater than the daily inflow of salt via the sea water? Seems dubious to me.

On the other hand, there are still many other benefits. Migratory birds love the Great Salt Lake. The Great Salt Lake Effect[0] on precipitation in this desert seems unambiguously positive.

[0] https://en.wikipedia.org/wiki/Great_Salt_Lake_effect

If you make it a bay of the Mediterranean, it should behave no differently than the rest of that ocean.

With the various pipeline/tunnel/channel options that are admittedly more realistic, at least at first, there might very well be the kind of problems you mention.

> there are still many other benefits.

Too bad it's going away.

https://www.theguardian.com/environment/2023/jan/10/utah-gre...

> Migratory birds love the Great Salt Lake

some birds, flying:

"hey you want to come and eat some shrimp?"

"yeah I could go for some shrimp, know anywhere good?"

"well yes actually, but it's a bit of a trek"

"okay cool, sky trip!"

Filling basins with ocean water will not increase the volume of sea water. It will probably increase the area of sea water (thus increasing evaporation, causing more precipitation, and speeding up the water cycle, which has a net cooling effect on the planet), and it will lower sea levels. Win win win win!

You're underestimating just how big the oceans are.

Agreed.

The biggest point that seemed missing to me: the author talked so much about increased evaporation, but isn't water vapor one of the worst greenhouse gases? Sure you mitigate sea level rise, but at the cost of increasing temperatures? That doesn't seem like a great tradeoff.

The water just moves, doesn't it? He's saying to build a canal.

I guess it depends on whether such canals increase the net surface area. If you raise the ocean by 3mm across the globe, does it result in the same net increase in surface area as flooding a large swath of the Sahara?

You are correct that water vapor is the primary greenhouse gas. Despite that, water vapor emissions are not generally considered to impact warming. I think that is because the water content of the atmosphere is already in balance due to the massive amount of evaporation and condensation (e.g. rain) that is constantly going on. If we dump some extra water vapor into the atmosphere, that will balance out as a bit of extra rain and/or a bit less evaporation somewhere else; atmospheric water vapor levels won't change.

I don't know whether a large scale, ongoing intervention, such as permanently flooding a large area, could nudge this balance sufficiently to result in a sustained (if small) increase in atmospheric water vapor content, and thus an increase in warming. An interesting question!

I wrote about the role of water vapor in global temperatures a while back at https://climateer.substack.com/i/60052576/you-thought-the-ma.... My primary source was an IPCC report, specifically the sidebar on pages 8 and 9 of this PDF: https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapt....

Presumably all these could be allowed to get saltier than the seas they fill from. That would allow more water to evaporate, which would speed up the water cycle, which has a net cooling effect on the planet, and which would cause more precipitation that would then help green the planet. It would also tend to lower sea levels. Win win win win!

XKCD talked about why flooding Death Valley in this manner would be a bad idea, because unless you remove all the salt and sediments left behind from evaporation it would create a toxic waste pool https://what-if.xkcd.com/152/

The story seems so nice, but maths and observations on Quattara basin don't add up.

First of all, climate around seas in deserted areas isn't much better than further in land. See the shores in Saudi Arabia, Dubai and Iran.

But let's suppose someone decides to build the pipe and extract energy. It means one has to build a 58 km pipe under the ground (which is doable, like Gothard base tunner in Switzerland).

Then, 4 issues remain:

1) you must treat the water coming in the pipes, because it's possible to clog the pipe, the turbine, etc.

2) what inclination do you need to get a reasonable discharge of water?

3) how much power one can extract from the flow? Rough estimates give me several megawatts per 10 m of elevation per 1 pipe of 10 m in diameter (this is the kind of size in new large-diameter tunnels). Seems like a lot of piping for not much power.

4) Erosion of the shores that may fill the basin up. This is what happens to natural lakes on plains.

And key issue here: the more you discharge through the pipe, the higher the level of water in the lake, the less energy you can extract.

Well, the air in Dubai is much more humid than in Riyadh (this is based on personal observation).

Does it feel better in Dubai than in Riyadh?

2) The Romans used an inclination of 1:1000. The Quattara basin is 80km from the Mediterranean and 60m lower. So it's not looking good straight away. As the water level rises, the drop will be even less.

Also, the amount of water that can evaporate from such a large area is immense, so you'd have to have a rather huge channel for the water coming in just to keep up.

The romans were using gravity to move the water "for free". Using gravity to generate electricity is a different concept.

A little follow-up:

1) the proposal suggests incompatible things: filling the sea, generating electricity from elevation difference (then you shouldn't fill it), and desalinating the water with the energy. If I understand correctly, desalination is very energy-intensive, so it's a big question whether a dam of 60m is enough to desalinate its own stream of water.

2) if it's just a pipe that lets water in, this may be like Garabogazköl gulf in Caspian sea, with salinity levels as high as in the dead sea -- and note that its inflow is 200m-wide canal, not a man-made 10 or more pipe.

https://en.wikipedia.org/wiki/Garabogazk%C3%B6l

3) costs of digging a trench are at least quadratic to its depth. To have it stable, the trench must have slopes at sides no more than 15%. This means the area of cross-section is depth^2 / 0.15. If it's just 100m, the cross-section is 66K m^2. If it's 200m, it's 266K m^2. At 100m depth, every km of canal is 0.06 km^3 of ground to move. At 200m, it's already 0.26 km^3 -- a quarter cubic kilometer per kilometer of length! Oh, that's why the engineers thought of nuclear blasts here.

So, unless humanity is ready to use nuclear weapons that massively, this idea is just a dream contradicting itself.

I used to dream of large scale solar and nuclear-powered desalination plants lining the mediterranean, solely for the purpose of pumping inland to create fresh water lakes to cool the local environment and perhaps stymie the increasing desertification of thre Iberian peninsula further north.

Then I grew up a bit and realised how mind-bogglingly massive such a scheme would have to be :)

These seems like a far more likely possibility, given the scale.

Given we might be in part historically responsible for a lot of the desertification around the periphery of the Med, I don't personally have major qualms about geo-engineering 'mostly useless' spaces back into something a little more fertile and a little cooler.

> and perhaps stymie the increasing desertification of thre Iberian peninsula

I think I get your point. I'm ready to take huge risks in order to support anything that may weaken the permanent African anticyclone.

Hmm, where were you and your keen insight thirty years ago to pour cold water on my adolescent mental machinations around helping dissuade creeping desertation around where i lived?

I was in Southern Italy, suffering for a weather that did not correspond to what I read in my school books, and learning to hate the words "Azores anticyclone".

And later I switched to yearning for the comparatively friendly Azores anticyclone every time the damned African anticyclone came uninvited to the heart of the Mediterranean Sea, and made itself at home for weeks at a time.

My partner's from Marche, and boy do they have a bit too much water at the moment... :/

> a little cooler

Hum... About this little bit, increasing low altitude humidity is almost guaranteed to make the place hotter, not cooler. Even if it adds vegetation.

Sounds a bit like the Desertec project.

> So why not play a Zanclean and flood it with water from the sea?

Why not? Because we're _really bad_ at modelling all possible outcomes, especially when it comes to large scale engineering projects.

There's always a chance it has downsides, but worst case you block the canal and it turns back into a dead sea.

I would say we are excellent at modelling outcomes, just bad at listening to models that tell us what we don't want to hear. For example, we knew about global warming before computers existed. The model and the tech wasn't the problem, human avoidance of bad news was (and is).

We can't just avoid doing everything because our models might be wrong. I find that reasoning repulsive. If humanity took that approach we would have died long ago.

I figure we've had enough examples of well-meant interventions that lead to worse outcomes to be really conservative about "just change the ecosystem and heat/salinity circulation patterns of two large bodies of water, what's the worst that could happen?"

We should be able to extrapolate from the large-scale reservoirs that have already been built. The proposed reservoirs would be 10x larger, so there would undoubtedly be learnings. But we would probably build such projects in stages, so that the project could be stopped or altered if the effect is negative.

You’re assuming linearity and arguing that all things are equal. I would be surprised if either of those things are true.

We _are_ being conservative. As the article mentions, these kind of projects have been proposed and studied for half a century now, and despite all the predicted benefits we haven’t event built a single one!

The pervasive "Let's never do anything, just to be safe" mood is what I dislike the most about this era. It is suffocating so many possible paths to progress.

"You never know" is always true, Don't use it as a crutch.

Note: I'm an old man complaining about this era, not OP.

> The pervasive "Let's never do anything, just to be safe" mood is what I dislike the most about this era. It is suffocating so many possible paths to progress.

To evaluate such a claim with anything approaching objectivity we would need a lot more detail.

What era are you speaking of? Why do you call it a ‘mood’? A mood of who exactly?

The way you phrase it is not an accurate characterization of what people mean when it comes to concern about unintended consequences. Your phrasing is a narrow, uncharitable criticism.

You might be attempting to reference to a concept called the precautionary principle?

> The precautionary principle (or precautionary approach) is a broad epistemological, philosophical and legal approach to innovations with potential for causing harm when extensive scientific knowledge on the matter is lacking. It emphasizes caution, pausing and review before leaping into new innovations that may prove disastrous. - Wikipedia

Criticisms are well articulated on the Wikipedia page. They are worth reading and discussing. They are fair and don’t rely on mischaracterizing what they criticize.

To be clear, I’m not taking a position here on the precautionary principle. I am suggesting: don’t be vague and don’t mischaracterize others’ positions. Sorry if this sounds harsh; it seems to me that people on Hacker News have the intellectual horsepower and time to think and write well.

The idea of the Qattara sea is fascinating. On paper, it sounds so easy: dig a long trench and let nature run its course.

There's so little life in the Sahara and there's so much Sahara around the theoretical sea that the ecological impact would be quite small for such a huge undertaking. With global temperatures continuing to rise and humanity preferring short-term profit over long-time survival, cooling even just a little bit of the Sahara could significantly extend the time people can live in northern Africa. I doubt we'll see the resurgence of the Green Sahara any time soon (the last period that kickstarted humanity in northern Africa was during an ice age, we're in the exact opposite situation of that) but even just a little bit of green and cool land in the desert could help a lot of people.

Salinity would need to be kept in check, of course, but with a corridor big enough for tides to flow between the Mediterranean and the new sea there should be a quite manageable maximum salinity. Until that happens, we could harvest osmotic power ("blue energy") from the water stream, as fresher water will rush into the salt water reservoirs if we do not allow the minerals to flow back.

Furthermore, with the new agricultural opportunities there need to be strict (and well-enforced) laws regarding pesticides and other types of contaminants to prevent another Lake Salton. With the current lack of agricultural possibilities in the area, this may actually be achievable if the government can see the long term benefits.

It all sounds so incredibly doable. I don't think it'll ever happen because of politics and economics, and even if the project does get started I doubt it'll be long until the various terrorist groups active in northern Africa will find a new location to make the world a worse place, but I'm still very curious about what kind of world such projects could create.

> Salinity would need to be kept in check, of course, but with a corridor big enough for tides to flow between the Mediterranean and the new sea there should be a quite manageable maximum salinity.

First of all, this is not what the OP is suggesting. OP is using pipelines and wants to generate electricity from the potential energy. And for good reasons: between the suggested Qattara sea and the Med, there sits El Diffa square in the way. Which is 200m above sea level. You could tunnel that with a pipeline. Trenching that for a channel would be quite the project.

Secondly, the Med only has a tidal range of 50cm. Using that to move a significant amount of water along a 100+km canal needs a truly humongous channel cross section.

OP suggests using electricity to desalinate his sea. This would take insane amounts of energy, creating freshwater from desalination at the rate its evaporating across thousands of square kilometers in the Sahara takes orders of magnitude more power than the power station is going to generate.

He also suggests using salt extraction pools. This only work, if rainfall creates fresh water rivers feeding his sea. Otherwise the water evaporating from this pool is lost to the sea, meaning you can only ever (at best) keep the salinity constant, but never decrease it.

I think it's best to face it from the beginning: we're creating another Dead Sea. Salinity will prohibit life in the water and directly at the shore. Rainfall might make it possible away from the shoreline.

But there will be absolutely no algae, shrimp or flamingos.

> Salinity will prohibit life in the water and directly at the shore.

Maybe these guys might survive: https://en.wikipedia.org/wiki/Brine_shrimp Also these: https://en.wikipedia.org/wiki/Ephydra_hians - not really impressive, but birds think they're yummy...

The salt extraction pools can reduce the salinity to the salinity level of the input water. The amount of effort needed increases as you approach the salinity level of the input so it isn't practical to achieve the exact same salinity level as the input water. In this case the proposed input water is from the Mediterranean which is not too salty for life.

I'm not sure how much more salty the sea can be while still having a reasonable ecosystem and an also not sure what ratio of extraction pools to sea surface area would be needed to achieve that so I don't know if it is actually practical.

> OP suggests using electricity to desalinate his sea. This would take insane amounts of energy

Well, making water fall 200m and desalinating sea water have around the same change in entropy. If you have a very efficient process, it will be close to break-even.

Or make Czech reservoir: https://prehrada.hrach.eu/en.html

I don't think inland seas will affect ocean levels?

I am sure the people living in Czechia will not like to live underwater.

It will solve the housing crisis...

Someone suggested a better project for Hungary (and surrounding countries): https://www.abclinuxu.cz/images/screenshots/1/0/250401-pouzi...

It requires only a small dam near Golubac.

The article seems to presuppose that being near a big amount of salt water will cause frequent rain, but the coastline of most of North Africa and the Arabian peninsula suggests otherwise.

Ocean currents are often cold. Cold water doesn't evaporate so readily.

Small, relatively shallow inland seas will be relatively warm; as such, they will evaporate readily.

Persian Gulf gets up to 32-34C in summer. How hot exactly are your proposed inland seas?

It is also quite small, though... hardly open ocean, and almost isolated by the Straits of Hormuz (?) from the ocean, so probably not much affected by deep sea currents, no?

Yes, but I'd say this further supports my assertion, given that rain is unusual on the Arab peninsula despite it being surrounded by warmer water

That is a fair point. :-)

The topography might be an issue, but still... touché.

I do not know much but a guess: air currents over oceans mean evaporated water doesn’t stick around as much as with rivers or lakes? Though I share your skepticism with the hand-wavy “mo water mo rain”

There are several factors, as I understand it, including which way the wind normally blows, the Hadley cell, and the location of mountains. All of these are applicable to the Qattara basin project.

This reminds me of the Salton Sea, a man-made lake in California which used to be promoted as a tourist destination and now continues to be an ecological disaster.

https://en.wikipedia.org/wiki/Salton_Sea

There is a similar "seaflooding" plan for that sea, and it is mentioned in passing at the end of the list of possible global sites in the article.

https://www.latimes.com/california/story/2022-10-05/panel-re...

An issue with flooding the Salton Sea to sea level is you'd submerge a lot of agricultural land that already exists to the north and south of the Sea. Plus a number of towns (like Coachella) that already exist in the area.

Though, if you could use this to maintain the water level and salinity at historical levels, you could avert the ecological disaster that's going to happen when the Salton Sea dries up. And it would likely become a popular area for recreation again, like it was in the 1950s and 60s.

you'd submerge a lot of agricultural land that already exists to the north and south of the Sea

Thus solving, or at least significantly migrating, the Colorado river over allocation problem. Win-win.

To be fair, it was accidentally created and so its water was intentionally cut off, causing the current ecological mess - which by the way also applies to other dried salt lakes too.

Also to be fair, it was created with water from a river that had all sorts of horrible run-off from farms in it, which is why it is so particularly toxic.

I'd expect projects like the ones mentioned in the article to be slightly cleaner than that, but still pretty awful.

I thought the run-off was just from surrounding farms and continues till now. Is that not correct?

Very interesting article. I like the idea of re-filling old dried out seas. Not much can go wrong (on first look), its doable and the benefits can be huge.

> not much can go wrong

The article says “ And with such a big new sea in a hot desert, a lot of its water would evaporate. This is good, because it would increase the amount of water being pumped in—generating more electricity—and it would increase the local moisture, which could increase local rainfall.”

Adding a ton of water to the atmosphere is going to cause rain. This may be mostly good but in a hot environment it could week be absolutely incredible downpours.

Downpours would have to be monsoon level before this caused problems. A new lake causing monsoon level rain? I doubt it but I've been surprised before.

Adding a ton of water to the atmosphere is going to cause more warming. Water vapour is Earth's most abundant greenhouse gas. It's responsible for about half of Earth's greenhouse effect.

It is vital to consider proportion: 2/3 of the Earth is ocean. These new seas would be absolutely tiny by comparison. The extra water vapour added to the atmosphere would be a rounding error. Unfortunately the same applies to the amount of sea level rise they offset: it too would be a rounding error, a fraction of a percent.

> Unfortunately the same applies to the amount of sea level rise they offset: it too would be a rounding error, a fraction of a percent.

Flooding Flood the Qattara Depression would lower the sea level by 3mm according to the article.

Yes... which is less than the current annual increase of 3.4mm:

https://sealevel.nasa.gov/faq/8/is-the-rate-of-sea-level-ris...

The West Anarctic Ice Sheet alone will cause ~3.3m rise when it collapses.

https://www.carbonbrief.org/guest-post-how-close-is-the-west...

Note, NOT melts; just when it breaks up and floats away, still frozen.

That one ice sheet, currently cracking, is over half resting on rock that is way below sea level. Some is 2000m under sea level. It doesn't need to melt, it just needs to break off and float away. That would cause a 3.5-5m *depending on ow much floated) increase in mean sea level, worldwide, in approximately 12 days.

That is over 1000x time the reduction caused by flooding the Qattara depression.

Or 0.1% -- or as I said, a fraction of a per cent.

Unlikely to be important, compared to the creation of irrigation and additional plants and greenery that generates O2 and absorbs CO2?

Before someone reading this thinks that drying up the planet would cool it down: water in the air acts as a greenhouse gas, but also cools the surface when it evaporates and helps reflect solar radiation when it forms clouds (major factor of our planet's albedo).

Also we are not comparing more water area vs less water area. Water will take more area in any case as sea levels rise. This way it just happens in a bit more controlled way.

It all depends on clouds, though.

It's always astonishing to me how pretty much every climatologist will tell you "clounds are the joker". It totally makes sense, but that doesn't make it in any way less fascinating and is kind of funny.

Adding water to the atmosphere does not cause more warming due to greenhouse effect at least not on this scale. Water vapor concentration is regulated by condensation, adding more water simply means more rain.

What is actually causing more warming is the increase of temperature, that changes the equilibrium vapor pressure point.

I’ve often wondered why we havent attempted something similar before. After all we have successfully drained the fens (in the 1600s, took only 7 years), constructed the hoover dam (1931, took 5 years), plus a dozen other significant geoengineering projects. There seems now to be a prevailing sentiment that geoengineering=bad among the general population.

I feel like the general mood is too risk averse for big projects like this at the moment. I hope I'm proved wrong though. I miss an age of optimism.

The Age of Optimism declined due to observed results.

I don't think long term pessimism has amazing results either.

It isn’t binary. Naive optimism and over-agency in a natural system seems to primarily function to bring information to the agent at the cost of system performance.

If what is here called pessimism results in the down-regulation of human impact and us largely getting out of the way of self-equilibrium-finding complex systems until we better understand them, then prudence very well might have amazing results.

That the systems are equilibrium finding and that said equilibrium will be ‘amazing’ are both quite bold assumptions.

We are just about to force future generations to (quite likely not) live through the unintended consequences of current and past generations ignorantly and recklessly engineering their environment out of a misguided desire “[grow] the economy, and [make] money along the way”, and in response the author seems to suggest we use more ignorance and recklessness to drive even more unintended consequences?

We don’t want to lose deserts and more than we wanted to lose forests and wetlands (and are now desperately trying to save them)… just because humans are too stupid to see the complex reasons why specific ecosystems exist doesn’t mean they should KEEP acting on that stupidity.

Out of curiosity, I checked what the air pressure would be in a drained Mediterranean, since the article claimed it would be oppressively high. The average depth of the Mediterranean is 1.5km [1] which is less than 2.0km which would be a pressure of 130.069kPa vs 101.312kPa at sea level [2]. This seems fine?

[1]: https://en.m.wikipedia.org/wiki/Mediterranean_Sea [2]: https://www.physicsforums.com/threads/air-pressure-below-sea...

It wouldn't crush you or anything, but it would be notable. Just like the difference between sea level and 2km above sea level is quite notable.

Not a fan of geo-engeering when it's the "sulfur dioxide sunscreen" trick, or iron fertiliser in the sea. This one I'm sure has side effects, but seems marginally more plausible.

If the climate-change induced sea level rise needs 1-2 metres of mitigation, and you have 100-200 metre deep depressions, you need to cover 1% of the Earth's surface (total, not just land) with these seafloods. Doesn't seem like a plausible mitigation, I'm puzzled why the article proposed it.

The other benefits might be interesting locally some places.

A few considerations: 1) you don't need to fully mitigate the sea-level rise for this to be of value. Even a few cm might make a difference on the margin for certain areas. 2) The projects themselves might be a value if we really could increase the productive value of currently arid parts of the land with net-positive environmental impact, so the sea-level rise doesn't matter or let's us do the project without worrying about sea-level drop.

If we really had too-cheap-to-meter power for desalinization, then these projects might start to make sense, but it seems too soon to me.

For a more nuanced view on the Egypt project in particular check the wiki page [0]

Short version is it sounds uneconomical for power generation. Hard to believe but reading between the lines it feels like despite all the “free” hydroelectric you’re looking at immense construction difficulties

You know your projects heading for the drawer when you propose using 100 atomic bombs to dig the tunnel

[0] https://en.m.wikipedia.org/wiki/Qattara_Depression_Project

PS I’d love for this project to work. The main thing I could not really find supporting evidence for is “water will fill with life”. Just like… you could be constantly desalinating (and now have a brine problem) and still not really have a great ecosystem form I feel like? But I don’t understand this.

That Wikipedia page talks about digging a 60 meters deep canal, not boring a tunnel.

People usually mentions sea rise as the worst outcome of global warming, but extreme weather may be more pervasive, and that may be experienced far earlier than the sea level rise.

In any case, this is at best a mitigation, not a solution. It sounds like a simple enough idea, and may not have as a disruptive impact as other geoengineering proposals that may end having unexpected consequences. Some of the proposed flooded areas could have unique ecosystems that may be negatively impacted, but anyway all ecosystems are being negatively impacted right now, so a delay in the very bad trends we might be in could be positive overall.

The article complains that places under the sea level have higher pressure and are "hell on Earth" because of that. Dead sea coast(currently lowest on-land point on Earth) has a higher pressure because of that, and it's beneficial for human health, it's a health resort.

The article seems to contradict itself (like the proposal to add water to salt so that we can evaporate the water and sell the salt :) ), and seems to be highly subjective and dishonest.

Ideally a sea level canal situation would allow for tidal forces to regulate salinity. The added bonus would be in shipping.

I'm not a civil engineer, but the idea that you can constantly generate hydroelectric power while desalinating with the derived electricity seems problematic.

https://energycentral.com/c/pip/great-mexicali-energy-and-sh...

Shipping to where exactly? How lucrative is the middle of the Sahara desert market?

What are the 2nd and 3rd order effects that we're missing?

Qattara depression lies in the Horse Latitudes that is full of arid deserts. So there's a high chance that flooding it might not make it turn into a lush wonderland. It could even end up being another dead sea.

1: https://oceanservice.noaa.gov/facts/horse-latitudes.html

Did anyone else notice the beautiful photography contained in this post? Unfortunately, after a quick scan, I could not find any attributions to the photos.

Some of them are stock photos from Getty. The map at the top is from one of sorgel's exhibitions for atlantropa, though I'm not sure if it his own design or something put together by another artist for the exhibition

Drying the Mediterranean Sea is surely a bad idea, but I wonder why nobody ever built hydroelectric generators into the Strait of Gibraltar. There is a huge steady flow of surface water from the Atlantic into the Mediterranean (1 million cubic meters per second), and almost as much flows back into the Atlantic in deeper layers. Why not tap into these streams to generate electricity?

Tidal energy is expensive - sea water is very corrosive and under water maintenance access isn't cheaply solved. Also you need to retain access for ships and subs.

The UK has the second highest tidal ranges in the world and is probably a world leader, we still generate nearly no energy from tidal.

> This would reduce global warming

No, water albedo is lower than Sahara desert, so it would capture more of the Sun's energy, and warm the planet.

Dress up the Dead Sea project to attract tourism, and Israeli/Jordanian co-operation will find a way.

Any talks of flooding anywhere with water/sea just remind me of the "Flood Ohio" meme, both in terms of practicality & humour:

https://www.youtube.com/watch?v=O4BPxKhRJRo

One major consequence of flooding Saharan basins could be the death of the Amazonas rain forest, as it depends on Saharan dust.

https://www.youtube.com/watch?v=ygulQJoIe2Y

I doubt it, the Qattara Depression is a fraction of the size of the Sahara. Marginally less fertile? Probably. Dead? No chance.

As I understood it, the Sahara is not a stable system and can relatively easily be greened again.

I'd wager that "Seaflooding" will just happen somewhere anyway, likely some where we ain't really looking.

And it will be fine. Mankind has seemingly surpassed weather patterns, and it now the 21st century.

Just reading this title made me suddenly think of wanting to live under the ocean/sea(closer to land albeit) like Sandy from SpongeBob. Affordable housing for all I guess.

at glance, if i divide the area of those deserts to the surrounding larger seas ... the ratio looks very small, maybe < .1% or much less (don't have numbers)

a drop in the ocean

https://en.wikipedia.org/wiki/Salton_Sea

Very interesting article and the whole idea of controlled sea flooding is well founded, but international geopolitics for sure is a major obstacle.

Some north African countries are very large, because they are mostly desert, which is a little inherent value, except perhaps for buried mineral resources. Therefore, some of these projects could be entirely within the boundaries of one nation.

Reply on news.ycombinator.com