6 ms·

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?

by mylons 4y ago

dsq 4y ago
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.
mym1990 4y ago
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.
jeffbee 4y ago
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.
- kube-system 4y ago
  Assuming that the center of Antarctica is still frozen after increasing energy consumption that much…
  - jeffbee 4y ago
    Wind or tidal power would be zero emissions and the most practical. You can use them directly without electrical conversion.
    - Ebree 4y ago
      Considering manufacturing, nothing is emissions free. Sea waves energy turbines are well engineered & safe for fauna not affecting water oxygenation unlike the other thing.
hnov 4y ago
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
anonporridge 4y ago
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-level/thermal-expansion https://sealevel.nasa.gov/understanding-sea-level/global-sea...
- BurningFrog 4y ago
  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.
  - anonporridge 4y ago
    > 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-how-much-saharan-dust-feeds-amazon-s-plants/ 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.
    - BurningFrog 4y ago
      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.
      - 4y ago
BurningFrog 4y ago
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.
aaroninsf 4y ago
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.
tuatoru 4y ago
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.

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?

by mylons 4y ago

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?

dsq 4y ago

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.

mym1990 4y ago

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.

jeffbee 4y ago

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.

kube-system 4y ago
Assuming that the center of Antarctica is still frozen after increasing energy consumption that much…
- jeffbee 4y ago
  Wind or tidal power would be zero emissions and the most practical. You can use them directly without electrical conversion.
  - Ebree 4y ago
    Considering manufacturing, nothing is emissions free. Sea waves energy turbines are well engineered & safe for fauna not affecting water oxygenation unlike the other thing.

hnov 4y ago

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

anonporridge 4y ago

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-level/thermal-expansion https://sealevel.nasa.gov/understanding-sea-level/global-sea...

BurningFrog 4y ago
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.
- anonporridge 4y ago
  > 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-how-much-saharan-dust-feeds-amazon-s-plants/ 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.
  - BurningFrog 4y ago
    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.
    - 4y ago

BurningFrog 4y ago

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.

aaroninsf 4y ago

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.

tuatoru 4y ago

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.