Geoengineering is not going to save the poles from climate change

Can carbon dioxide emissions still increasing, can geo-engineering stop the merger of the glacial caps of Greenland and Antarctica and prevent massive increases in the sea? No, according to an examination of the five main ideas of polar geo-engineering offered so far.

The promotion of geo-engineering ideas which cannot work distracted the attention of the key issue, explains Martin Siegert at the University of Exeter in the United Kingdom. “It becomes something that works against what we have to do, which is to decarbonize.”

Siegert and his colleagues have evaluated each idea of ​​polar geo-engineering according to six criteria: will it work, can it be done on the required scale in a reasonable time, is it affordable, will the countries be accepted and will they be able to support this agreement for many decades, what are the environmental risks and will they increase false hopes?

In Antarctica, some glacial caps rest on the seabed and are melted from below by warming ocean waters. An idea proposed to save them is to build immense “curtains” to prevent hot currents from reaching these glacial caps and floating shelves that help protect them.

It is not clear if it would help, explains Steven Chown, member of the team at Monash University in Australia.

“Lukewarm water may well be diverted from an ice shelf, but the question is where it is going?

Such curtains should be anchored to the seabed to depths up to 1 kilometer, extend up over hundreds of meters and stretch for at least tens of kilometers – and they should be built in an extremely difficult environment, explains Chown.

Half of the research cruises in Antarctica turn away from their expected courses due to the dangers of icebergs and sea ice. “It is simply too dangerous,” he said.

A single ship has ever managed to reach the area where a sea curtain should be built to protect the “Doomsday” Thwaite glacier, adds Chown.

With glaciers that are seated on earth rather than on the seabed, concern is warming temperatures causes more liquid water under the ice, which acts like a lubricant that accelerates the flow of ice. More ice reaching the sea means more elevation in sea level.

Thus, a proposal is to unravel holes through the ice to pump all the water below.

“This would require a large amount of holes through extremely deep ice areas-perhaps miles in thickness-far beyond any scientific drilling project that has ever occurred,” said Sammie Buzzard at the University of Northumbria in the United Kingdom.

We do not even know where the water is and where drilling. “But even if we understood where to break better, we always have the problem of scalability, the problem of costs, the problem of switching on this drilling,” explains Buzzard. “Even if we understand science better, it is still not an achievable idea.”

Another idea is to cover the surface of the Arctic Ocean with tiny hollow glass pearls to further reflect the heat of the sun in space and cool the region. “”[But] It may well have the opposite effect, ”explains Chown.

Maintaining this coverage would require 360 ​​megatons of glass beads to be produced each year, which is equivalent to the total global production of plastic. A project to try the idea was closed after laboratory tests showed that pearls were toxic.

Then there is the injection of stratospheric aerosols – release substances such as sulfur dioxide in the stratosphere to form aerosols that reflect sunlight. It is much more problematic on Poles than elsewhere. Aerosols do not remain in the polar stratosphere for as long as on the tropics, for example, and they make little difference during the dark polar winters, or above the ice or reflective snow.

It would therefore be necessary for very large amounts of aerosols. This could exhaust the ozone layer and disturb the climate elsewhere, explains Valérie Masson-Delmotte at the University of Paris-Saclay in France. Countries that are negatively affected could require compensation.

Some have suggested the idea of ​​thickening sea ice in the Arctic by pumping seawater on it. “This would require millions of devices deployed through drift and fracturing ice,” said Heïdi Sevestre to the Arctic surveillance and evaluation program in Norway. “This is technologically, logistical and financially unrealistic.”

The final idea that researchers has evaluated is to fertilize the southern ocean to stimulate the growth of phytoplankton, which eliminates carbon if more organic matter is locked in sediments of the seabed. But through 12 small tests, more carbon reached the seabed in one. And this approach could accelerate the loss of oxygen in the oceans, potentially increasing the release of powerful greenhouse gases such as nitrous methane and oxide, explains Masson-Delmotte.

“I was extremely concerned about the discussions where some supporters of these approaches were too enthusiastic and had a very simplistic [view] Challenges, “explains Masson-Delmotte.” I think this work deals with such gaps. “”

Siegert thinks that new research on these ideas is a waste of resources. “The impossibility of the scale is something that you cannot look for,” he says.

Not all researchers are convinced. “I don’t think it’s enough of these approaches to be removed from the table,” said Shaun Fitzgerald at the Center for Climate Repair in Cambridge, in the United Kingdom.