Harvard scientists say wild plan to mitigate sun's effects could work safely



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For something that is supposed to help save the planet, solar geoengineering certainly has a lot of enemies.

Critics warn that artificially reflecting sunlight to cool the planet could have dramatic and unexpected consequences – but a team of scientists led by Harvard insists that such fears are exaggerated.

In a new study, researchers say that spraying chemicals into the atmosphere to darken the sun has never been a magic solution to remedy the dangerous dependence of humanity on the burning of fossil fuels, but if used with care, the goal being to halve the increase in global temperature – This could work safely after all.

"Some of the problems identified in previous studies in which solar geo-engineering offsets any warming are examples of the old adage that the dose makes the poison," says Harvard University physicist Keith.

"There are still big uncertainties, but climate models suggest that geoengineering could generate surprisingly uniform benefits."

Although solar geo-engineering is more than half a century old, it is only more recently – since the planet's climate catastrophe has become more obvious – that science has been deepened.

Indeed, more than 100 articles have explored the possibilities of this seemingly radical idea of ​​cooling the planet with atmospheric particles reflecting sunlight.

Among the research work done, Harvard scientists have gone further than most of them by launching the largest solar geoengineering study in the world – which is expected to conduct its first field experiments this year – in order to see how these chemicals behave in the sky.

But the new paper does not concern this project. Like most geoengineering research, his conclusions are based on modeling. in particular, a simulation of what would happen if CO2 emissions in the atmosphere were doubled and if solar geoengineering was used to halve the temperature increase resulting from carbon accumulation.

According to the results of what researchers recognize as a simplified "idealized" scenario, the moderate geoengineering strategy would cool the planet without exacerbating climatic stresses in the vast majority of regions, such as extreme rainfall production or worsening hurricanes. .

In all, 85% of the increase in hurricane intensity would be offset by solar geo-engineering, and less than 0.4% of ice-free land would see exacerbated climate stress.

"Previous work had assumed that solar geoengineering would inevitably lead to winners and losers, with some regions more affected, and our work challenges that assumption," said Peter Irvine, Harvard's first author and researcher in solar geoengineering. John A. Paulson School of Engineering. and applied sciences.

"We are seeing a significant reduction in climate risk as a whole, without increasing risks for all regions."

Despite the promise of these hypothetical figures, the team recognizes that there is still much we do not know about the impact of solar geoengineering on the atmosphere and the land below.

The researchers also pointed out that our main response to climate change should be to reduce our carbon emissions because geo-engineering can not repair the root cause of our environmental dilemma, even though it remains to be examined.

"I'm not saying we know it works and we should do it now," Keith said. The Guardian.

"Indeed, I would absolutely oppose deployment now … there is a lot of uncertainty."

But as long as uncertainty persists, the world is warming up – and it is clear that solar geoengineering must be examined as part of the world's response to climate change.

This very week, the United Nations Environment Assembly is meeting to discuss how technologies such as solar geoengineering and carbon capture should be controlled.

With the fate of Earth's future climate in the balance, it is essential that solar geoengineering – its defenses and detractors – be scrutinized.

"How to understand and exploit new disruptive technologies for the benefit of humanity as a whole is one of the defining issues of our time," said former UN Secretary-General Ban Ki-moon, in a statement posted about the meeting.

"Future generations will not forgive us if we fail to respond convincingly."

The results are reported in Nature Climate change.

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