Geoengineering—deliberate large-scale human manipulation of the climate as a way to mitigate soaring CO2 emissions—is a technological path towards further climate chaos with potentially disastrous consequences, a new study warns.
Using computer simulations to look at the long-term global consequences of several climate engineering methods, the researchers found that these methods could provide only minor benefits to reducing global warming but could spark severe side effects.
The study looked at five widely discussed strategies: reducing incoming solar radiation through atmospheric aerosols or mirrors, 'greening' large desert areas in North Africa and Australia by wide-scale tree planting, and three different ways to manipulate the ocean including ocean alkalinization.
"All of the methods have unintended side effects," the authors found, and are relatively ineffective—less than 8 percent—at reducing warming in comparison to the expected trajectory of CO2 emissions.
The afforestation technique, in fact, could make warming worse.
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"The forests removed carbon dioxide from the atmosphere, but at the same time the earth's surface became darker and could store more heat," lead author Dr. David Keller explained.
Other problems could occur if a climate engineering method was stopped.
While they found that reduction of solar radiation could slow down warming significantly, if that measure were suddenly stopped after 50 years, for example, that could spark a several-degree global warming increase in just a few decades, and "This change would be much faster than the current rate of climate change, with potentially even more catastrophic consequences," said Keller.
In all their simulations, atmospheric CO2 "still reaches more than twice the current level by the end of the century," the authors write.
The best way to deal with climate change, the authors conclude, is to mitigate CO2 emissions