titaniumbiscuit

I have a question regarding a proposed method of glacial #geoengineering: drilling a bunch of holes into #glaciers in #Antarctica and then pumping up the water that sits underneath them to allow the glacier to fall back down on the solid rock beneath to prevent further melting of it's underside and to slow down their speed. The water is then spread at the surface where it refreezes.

My question is: the water is seawater, so contains salt. What happens to that salt during the refreezing? Do we then have a bunch of salty brine sitting around on the surface? What consequences could that have?

(This method was mentioned in Kim Stanley Robinson's book The ministry for the Future, and was also mentioned in passing in the recent glacial geoengineering white paper mentioned here: https://www.science.org/content/article/avoid-sea-level-rise-some-researchers-want-build-barriers-around-world-s-most )

#climatecrisis #fediclimate #climate

Jul 24, 2024 at 9:47amWeb
Show threadJulius GarbeJul 24, 2024
@titaniumbiscuit Nearly all water underneath glaciers is produced through basal melting of the ice and is hence fresh water - it‘s not water from the sea.
Anyway, I‘m more than sceptic that this method will be feasible at the large scales that are required if we do not halt global warming.
Show threadtitaniumbiscuitJul 24, 2024

@juliusgarbe Thanks. It might indeed be sweet water.

And yeah, halting carbon emissions would be needed in any case. But slowing down the melting of glaciers would be helpful to delay or reduce sea-level rise which would destroy the majority of coastal cities. (Because afaik even if you stopped emitting today, the warming due to existing CO2 would continue for quite some time.) And also yes, the scales seem to be mindboggling...

Show threadJulius GarbeJul 24, 2024
@titaniumbiscuit These types of large-scale geoengineering are simply insane. There are still 60 meters of global sea level rise frozen in the Antarctic ice – enough to drown almost all of the world's coastal cities. We cannot stop this with technology alone if we do not reduce global warming.
Show threadJulius GarbeJul 24, 2024
@titaniumbiscuit The additional warming after the end of all emissions ("zero emissions commitment") is in fact very small. But as long as we do not reduce the CO2 concentration in the atmosphere, the temperature will remain warmer and the ice will continue to melt.
Show threadtitaniumbiscuitJul 24, 2024

@juliusgarbe Is it so small? I read in Wikipedia that CO2 remained in the atmosphere for quite a long time, retaining its warming effect during that whole time.

And yes, for sure, emissions need to stop soonest and everything needs to be done to achieve that. Plus then some negative emissions. (Note that I am not advocating for or against geoengineering, but simply asking if someone has some insights into the matter.)

Show threadJulius GarbeJul 24, 2024
@titaniumbiscuit I was referring to the *additional* warming that would still occur after complete emission phaseout. This is likely to be rather small.
But of course all the warming that has already occurred up to this point will remain, because the CO2 that is already in the atmosphere will remain there for centuries into the future, as you rightly pointed out.
The only way to reduce the temperature is to actively remove CO2 from the atmosphere.