Geoengineering is often presented as a last-resort technological fix to the climate crisis that can still swoop in and save the day.

But new models suggest that such risky measures, like dimming the Sun, are not enough to save Antarctica now.

There's only one thing left that could, and it's the very same thing we've been failing to do for 40 years now: stop burning fossil fuels.

In the face of disastrous fires, floods, and other extreme weather events that have plagued the Northern Hemisphere's summer, there's been renewed interest in the potential of geoengineering. The incentive to try potentially dangerous solutions will only grow stronger as climate-driven disasters intensify.

"The window of opportunity to limit the global temperature increase to below 2 degrees is closing fast, so it is possible that technical measures to influence the climate will be seriously considered in the future," says University of Bern glaciologist Johannes Sutter.

So Sutter and colleagues decided to investigate what impact dimming the Sun would have on one of the fast approaching climate tipping points that researchers are most concerned about.

"Observations of ice flows in West Antarctica indicate that we are very close to a so-called tipping point or have already passed it," explains Sutter, "with our study, we therefore wanted to find out whether a collapse of the ice sheet could theoretically be prevented with solar radiation management."

The region is already missing concerning amounts of ice, despite it currently being the middle of winter there. This includes a reduction in the sea ice that dams West Antarctic glaciers in place on land. The melting of West Antarctica would lead to meters of sea level rise and all that extra fresh water in the sea could also contribute to a collapse of the ocean's currents, which are already slowing down.

The melt is happening faster than anticipated and already decimating wildlife.

Sutter and colleagues simulated ice sheet conditions under high, moderate, and low emissions pathways and four different stratospheric aerosol injection scenarios.

While the researchers' modeling showed dimming the Sun by spraying millions of tons of sulfur dioxide into the stratosphere by 2050 could delay the ice collapse, it would only work in combination with decarbonization and only in the moderate or low emissions pathways.

"As long as atmospheric greenhouse gas concentrations remain high, solar radiation management would most likely have to be continued for centuries, perhaps even millennia," the researchers explain.

If sun-blocking management strategies were to suddenly stop we'd risk termination shock, where an even more abrupt temperature increase would occur along with more severe consequences. Also, the other problems caused by the excess CO2 in our atmosphere would continue unabated.

"Solar radiation management could have impacts on regional weather patterns detrimental to society and the biosphere and other still-unknown effects, while not addressing the direct adverse effects of rising atmospheric CO2 such as ocean acidification," Sutter and team write.

What's more, the only scenario that revealed a chance at stopping the West Antarctic ice sheet collapse involved cutting back on carbon emissions.

"Our simulations show that the most effective way to prevent long-term collapse of the West Antarctic Ice Sheet is rapid decarbonization," warns Sutter.

Sources

Published: 10 August 2023 in Nature - Climate intervention on a high-emissions pathway could delay but not prevent West Antarctic Ice Sheet demise

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