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Comment by mylons | Hacker News Reader

if we start mass desalination (just assume we can), would that have any impact on sea levels? what if it were on a scale of irrigating deserts, etc?

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The only brute force solution to reducing sea level rise that might be reasonable is to pump sea water into a dammed desert basin, e.g. Sahara or Australia.

The mass of water you would have to displace to handle what's melting off Greenland and Antarctica on top of thermal expansion of the oceans due to hotter water[0] would make this the biggest mega project humanity has ever attempted, by several orders of magnitude.

From a purely economic and technical perspective, it probably makes drastically more sense to just gradually abandon parts of our coastal cities as they submerge and retreat inland.

[0] - https://sealevel.nasa.gov/understanding-sea-level/global-sea...

Building a canal from that makes the Qattara Depression in Egypt a part of the Mediterranean would lower ocean levels by 4cm.

Seems worth doing just to bring life to the desert.

> Seems worth doing just to bring life to the desert.

Possibly. But you also have to consider the knock on effects of making such a drastic change to Earth's ecosystem.

Life to the desert could lead to death to the rainforest...

https://www.nasa.gov/content/goddard/nasa-satellite-reveals-...

Neil Stephenson's Termination Shock is a great narrative about how any kind of active attempt to address climate change chaos could lead to near hopeless geopolitical complexities.

You can always make a "you never know" argument, and you'll always be right.

I'm really tired of the "let's not do anything, just to be safe" attitude. Systemic inaction has a huge cost of its own.

When did I say we shouldn't do anything?

You should read Termination Shock. It makes a great case for why doing things is hard, but also worth it. Sometimes it just takes someone with sufficient power and courage to do what's right and accept the hatred and violence that will inevitably come their way for disrupting the establishment order.

But sadly, most modern people are too weak to stick their necks out like this.

You didn't say that, to be fair.

I think it's a serious problem of this era, and your post sounded like those arguments to me.

Let's do nothing is more reasonable comparing to do something now not minding consequences. This overreaction "2019 syndrome" brought grave results to humanity. If sea rise is result of warming, flooding deserts is opposite to role of deserts which reflect heat back to space through vapour-free sky. Logically there is more sense in deserting bigger part of world to increase this process what global depopulation promoters would also love. But problem with global solutions is they are assuming totalitarian centralised global Earth management which is undemocratic, political & tends to promote particular big corporate interests not common good. It replaces scientific discourse & convincing through arguments, building organic non-obligatory consensus with censoring free speech & access to raw data, political pressure, coercing tactics building unhealthy psychosis in people, through emotions killing reason and objective truth. That's not the world & humanity we want to save. I don't understand why we don't paint all roofs white yet. It's something anybody can do to help reflect heat if he believes warming is a problem (not historically low oxygen level in atmosphere earth's life breaths with or possibility of freezing people & soils to death..).

There was a proposal to just pump seawater inland to the center of Antarctica. That would consume a monumental amount of energy, of course, but is technologically feasible.

Assuming that the center of Antarctica is still frozen after increasing energy consumption that much…

Wind or tidal power would be zero emissions and the most practical. You can use them directly without electrical conversion.

Considering manufacturing, nothing is emissions free. Sea waves energy turbines are well engineered & safe for fauna not affecting water oxygenation unlike the other thing.

I can't even imagine how it would impact sea levels at all.

A mechanical thing that would work is digging up material from the seafloor and dumping it on land.

The costs have to be astronomical though, aside from environmental considerations.

At some point all excess water flows to the sea or evaporates into the atmosphere, where it turns to rain and then to the sea. So sea (ocean, really) levels do not change.

In The Ministry for the Future, which is speculative fiction about attempts to mitigate climate change and its impacts,

one small sub-plot is the idea of seeking to freeze the motion of ice sheets and glaciers, by pumping the water serving to lubricate their motion to the surface to refreeze. Not exactly the same idea, but similarly ambitious.

Surface area of the oceans is 361e6 km², let’s say each of 7e9 people using 200 liters of water daily (obviously way more in the developed world but a lot of the world still living in huts), 1e8 dm² in km² (since liters are dm³) you have

(7e9 * 200) / (361e6 * 1e8) = 0.00003878116 decimeters of sealevel/day = basically imperceptible

I mean at a fundamental level if you can take out the same amount of water(or more) as is melting, yes. But I think from the shear size of the problem, most people have a hard time reasoning about just how much water we are talking about.

If it's instead of pumping out inland aquifers, yes.

Sea level rise would be reduced by maybe a quarter of a millimeter per year.

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