Can we gradual the melting of the ice caps?
Ulrik Pedersen/NurPhoto/Shutterstock
With carbon dioxide emissions nonetheless rising, can geoengineering halt the melting of the Greenland and Antarctic ice caps and stop huge sea stage rises? No, in keeping with a evaluate of the 5 fundamental concepts for polar geoengineering proposed up to now.
Selling geoengineering concepts that can’t work distracts consideration from the important thing problem, says Martin Siegert on the College of Exeter within the UK. “It turns into one thing that’s working in opposition to what we have to do, which is to decarbonise.”
Siegert and his colleagues assessed every polar geoengineering thought based mostly on six standards: will it work, can or not it’s finished on the scale required in an affordable time, is it reasonably priced, will international locations conform to it and be capable to preserve that settlement for a lot of a long time, what are the environmental dangers and can it elevate false hopes?
In Antarctica, some ice sheets relaxation on the seabed and are being melted from under by warming ocean waters. One proposed thought to save lots of them is to construct immense “curtains” to cease heat currents from reaching these ice sheets and the floating ice cabinets that assist defend them.
It isn’t clear if this may assist, says group member Steven Chown at Monash College in Australia.
“Heat water could be diverted from one ice shelf, however the query is the place does it go to? It might properly simply go to the ice shelf subsequent door, creating a distinct downside,” he says.
Such curtains must be anchored to the seafloor at depths of as much as 1 kilometre, prolong upwards for a whole bunch of metres and stretch for tens of kilometres at the very least – they usually must be in-built a particularly difficult surroundings, says Chown.
Half of analysis cruises to Antarctica get diverted from their deliberate programs due to the hazards of icebergs and sea ice. “It’s simply too harmful,” he says.
Just one ship has ever managed to succeed in the world the place a sea curtain would must be constructed to guard the Thwaites “doomsday” glacier, Chown provides.
With glaciers that sit on land slightly than the seabed, the fear is warming temperatures are leading to extra liquid water beneath the ice, which acts as a lubricant that quickens the ice movement. Extra ice reaching the ocean means extra sea stage rise.
So one proposal is to drill holes down by the ice to pump out all of the water beneath them.
“This might require a considerable amount of holes by extraordinarily deep – presumably kilometres thick – areas of ice that’s far past any scientific drilling undertaking that’s ever occurred,” says Sammie Buzzard at Northumbria College within the UK.
We don’t even know the place the water is and the place to drill. “However even when we understood the place to drill higher, we nonetheless have the scalability downside, the associated fee downside, the issue of powering that drilling,” Buzzard says. “Even when we understood the science higher, it nonetheless isn’t a possible thought.”
One other thought is to cowl the floor of the Arctic Ocean with tiny, hole glass beads to replicate extra of the solar’s warmth again into house and funky the area. “[But] it might properly have the alternative impact,” says Chown.
Sustaining this cowl would require 360 megatonnes of glass beads to be produced annually, which is equal to the overall international manufacturing of plastic. A undertaking aiming to attempt the concept was shut down after lab assessments confirmed the beads have been poisonous.
Then there may be stratospheric aerosol injection – releasing substances similar to sulphur dioxide into the stratosphere to type aerosols that replicate daylight. That is far more problematic over the poles than elsewhere. Aerosols do not stay within the polar stratosphere for so long as over the tropics, say, they usually make little distinction throughout darkish polar winters, or above reflective ice or snow.
So very massive portions of aerosols can be required. This might deplete the ozone layer and disrupt the local weather elsewhere, says Valérie Masson-Delmotte at Paris-Saclay College in France. Nations which might be adversely affected would possibly demand compensation.
Some have instructed the concept of thickening the ocean ice within the Arctic by pumping seawater on prime of it. “This might require thousands and thousands of units deployed throughout drifting, fracturing ice,” says Heïdi Sevestre on the Arctic Monitoring and Evaluation Programme in Norway. “That is technologically, logistically and financially unrealistic.”
The ultimate thought the researchers assessed is fertilising the Southern Ocean to spice up phytoplankton development, which removes carbon if extra natural matter is locked away in sediments on the seafloor. However throughout 12 small trials, extra carbon reached the seafloor in just one. And this method may speed up oxygen loss within the oceans, probably rising the discharge of potent greenhouse gases similar to methane and nitrous oxide, says Masson-Delmotte.
“I’ve been extraordinarily involved by discussions the place some proponents of those approaches have been over-enthusiastic and had a really simplistic [view] of the challenges,” says Masson-Delmotte. “I feel this work addresses such gaps.”
Siegert thinks additional analysis into these concepts is a waste of sources. “The impossibility of scale is one thing you may’t analysis out,” he says.
Not all researchers are satisfied. “I don’t assume sufficient is thought about any of those approaches for them to be taken off the desk,” says Shaun Fitzgerald on the Centre for Local weather Restore in Cambridge, UK.
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