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The scientific consensus is that the Earth is warming, and some climate experts wonder if we might reach a point when we need to do something to try to cool the planet, something drastic, like creating artificial clouds to reflect sunlight back into space. Talking about this kind of thing used to be almost taboo among scientists. NPR's Nell Greenfieldboyce reports that's not only changing, some of the nation's top researchers say they are options we can no longer afford to ignore.
NELL GREENFIELDBOYCE, BYLINE: Not too far from the White House is the historic National Academy of Sciences Building. It's got a big statue of Albert Einstein out front, and it is the home of the country's scientific establishment. So it was a little jarring to hear folks here talking about deliberately messing with the planet's thermostat. This is sometimes called climate geoengineering.
MARCIA MCNUTT: All of us are mostly pretty scared of geoengineering.
GREENFIELDBOYCE: Marcia McNutt is a geophysicist and editor-in-chief of Science, the influential research journal. Despite her fear, she agreed to chair a committee that looked into this. Given that the world isn't doing much to limit the greenhouse gas emissions that cause climate change, she felt like she had to.
MCNUTT: It is prudent to ask ourselves what is the science behind climate intervention strategies.
GREENFIELDBOYCE: Reporters and researchers gathered today as her committee released two new reports about that science. One report looks at the possibility of quickly cooling the planet by sending sunlight back into space. This could be done by having airplanes release sulfuric acid in the stratosphere, creating aerosols that reflects sunlight. The report says this approach would be doable with today's technology. Still it would be incredibly risky with unknown effects on the ozone layer and global precipitation. The committee said don't do it now, but it is something we need to research further and understand.
MCNUTT: There would need to be a lot of work before we would know whether the risks could be reduced.
GREENFIELDBOYCE: The second report looks at a less controversial approach - sucking carbon dioxide out of the air. McNutt says this would be slow and expensive, but it's not dangerous. Direct-capture technologies are still in their infancy, but there are tried-and-true measures, like planting forests
MCNUTT: We should be doing that - better land-use management - we should be doing that - duh. These are absolutely things that we should be pursuing.
GREENFIELDBOYCE: But spewing sulfuric acid into the atmosphere - you're not so down with that.
MCNUTT: I'm not down with that. I hope we never get to that point and I think we need to know exactly what the ramifications are before someone does it to us or before someone thinks it would be a good idea.
GREENFIELDBOYCE: Now, scientists are always calling for more research. But this time it really is a big deal because this is such a prestigious government advisory group, and this is such a contentious area of science. David Keith is a climate science researcher at Harvard University.
DAVID KEITH: What I hope it will do is give government officials an excuse to move.
GREENFIELDBOYCE: He says there's been a reluctance to fund research on climate fixes. He thinks officials worry that even just talking about this could undermine the sense of urgency about cutting greenhouse gas emissions.
KEITH: That is the underlying fear, separate from all the science, that really is the thing that makes people squeamish.
GREENFIELDBOYCE: Despite these concerns, scientists say they need to understand the risks and benefits of what kind of things could be done if only because someday other nations might want to do something. The initial funder for this scientific review was the U.S. Intelligence Community. Alan Robock is a climate scientist at Rutgers University. He says there's the potential for real conflict.
ALAN ROBOCK: If you could do it, what temperature would you like to set the planet's thermostat to, and who controls that thermostat?
GREENFIELDBOYCE: Countries might decide to act unilaterally. There might be disagreements. Robock says there's an international agreement not to modify the environment for hostile purposes, but who decides what's hostile?
ROBOCK: If you say I'm doing it because I want the planet to be cooler and I don't want my sea level to rise, and somebody else says yeah, but you're affecting the frequency of droughts in my country - is it hostile or not?
GREENFIELDBOYCE: That's not a question science can answer. But that kind of scenario is why scientists say they need to start learning more about climate interventions now. Nell Greenfieldboyce, NPR News.
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