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If we start deliberately cooling the Earth, we may not be able to stop

If we start deliberately cooling the Earth, we may not be able to stop


Geoengineering isn’t a silver bullet

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Blasting aerosols into the sky to reverse climate change seems like an exciting proposition, but it may be too dangerous to attempt: If we try and then suddenly halt this form of geoengineering, it could cause more damage than climate change itself, according to new research.

Global warming is a pressing problem, and some scientists believe that sending a plane to spray sulfate aerosols into the sky will help cool down the Earth. In a study published today in the journal Nature Ecology & Evolution, researchers used models to predict what would happen if we sprayed the aerosols for 50 years, and then abruptly stopped. They found that this scenario would cause the Earth to warm up too quickly to give animals time to move to more comfortable environments, leading to a huge loss of plant and animal species. The effects would be two to four times worse than with global warming alone, according to the study.

The aerosol plan, called stratospheric aerosol injection, is still speculative for now. The idea is that spraying aerosols will build a reflective layer that blocks out part of the Sun to cool the Earth. The process already happens naturally, when volcanoes erupt, and there is some science supporting efforts to try this artificially.

But it’s a big endeavor that could have big consequences. Today’s paper says that using aerosols to cool the planet might distract us from the fact that heat-trapping greenhouse gases are still being pumped into the atmosphere. Then, if we suddenly stopped, those gases would heat up everything very quickly, leading to disasters like less rain and more fires. Another recent paper suggested that aerosol injection would have different effects on different hemispheres, possibly leaving the northern hemisphere with fewer cyclones while plunging sub-Saharan Africa in drought.

Of course, most people who advocate for geoengineering say that it’s a solution to buy us more time for reducing greenhouse emissions — meaning that we’d be monitoring the greenhouse gases all along and trying to reduce them no matter what. Still, geoengineering is politically tricky, and politics is messy, as the current government shutdown in the US proves. So consider this another warning.