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Blocking the sun to save the planet?

Blocking the sun to save the planet?

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Scientists are considering drastic measures, like deflecting sunlight, to save our warming climate. What would be the impact on our food crops?

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We are now in the times of drastic measures to halt the warming climate. For instance, scientists are seriously considering trying to deflect the sun’s rays from hitting the Earth, also known as sunshade geoengineering. But often trying to fix complicated issues leads to a bigger mess. Removing sunlight would threaten our food and water supply. Right?

Well the opposite might be true. New research out of The Carnegie Institution for Science published yesterday in the journal Nature Climate Change finds that deflecting sunlight away from Earth may just help increase crop yields.

Inspiration for the concept of sunshade geoengineering came from erupting volcanoes that shade the planet with small particles. But within a year the particles fall and the planet re-heats. So one option for replicating this natural phenomenon is to use high-flying airplanes to keep replenishing small particles in the stratosphere in order to scatter sunlight.

The Carnegie scientists used climate models to test the impact of shading the planet. They simulated climates with the CO2 levels of today as well as those with double the level of CO2 levels. Should we continue to burn fossil-fuels at today’s rate, it is the double levels of CO2 that we'll be dealing with in about three decades. The researchers then simulated what it would be like if we added a layer of sulfate aerosols in the stratosphere which would deflect 2 percent of sunlight from reaching Earth. And these changes were applied to crop models used in predicting future yields.

And they found that such deflection of sunlight would lead to increased yields in most regions for both projected levels of CO2. But why? How? Deflecting sunlight reduces temperatures but not CO2. Reducing temperatures is a good thing for the plants, but they get a further boost with the higher concentrations of fertilizing CO2.

To be sure, however, the models also predict that some areas might be harmed by the slightly darker days. Some experts also worry that such a drastic measure doesn’t solve the issue of ocean acidification, which is causing massive deterioration of coral reefs and basically impacting every corner of sea life. Plus there are plenty of political issues regarding high-flying planes traversing the Earth spewing aerosols.

"The climate system is not well enough understood to exclude the risks of severe unanticipated climate changes, whether due to our fossil-fuel emissions or due to intentional intervention in the climate system," said Julie Pongratz of Department of Global Ecology at the Carnegie Institution, in a press release. "Reducing greenhouse gas emissions is therefore likely a safer option than geoengineering to avert risks to global food security."

[Photo onlinewoman]

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Christie Nicholson

Contributing Writer

Christie Nicholson produces and hosts Scientific American's podcasts 60-Second Mind and 60-Second Science and is an on-air contributor for Slate, Babelgum, Scientific American, Discovery Channel and Science Channel. She has spoken at MIT/Stanford VLAB, SXSW Interactive, the National Science Foundation, the National Research Council, the Space Studies Board and Brookhaven National Laboratory. She holds degrees from the Columbia University Graduate School of Journalism and Dalhousie University in Canada. She is based in New York. Follow her on Twitter. Disclosure