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Harvard team thinks putting sunglasses on the Earth might buy time to solve global warming

Solar geoengineering mimics the good part of a volcanic eruption.

If the Earth is too hot, what if we just block some of the sun hitting it? That's the basic idea behind a solar geoengineering project at Harvard that is progressing toward an important trial.

"Geoengineering is the concept of intentionally altering the Earth's climate to suit our needs," says Colleen Golja, a PhD candidate and researcher at Harvard's Solar Geoengineering Research Program. That team is working on stratospheric aerosol injection "meaning you would put very tiny, reflective particles in the stratosphere and they would kind of work like sunglasses for the Earth," explains Golja. The key is the albedo of the particles, the measure of their ability to diffuse and reflect the sun's energy.  


Albedo is a measure of solar reflection that is key to the study of what particles might be usable to reduce the sun's energy.

Harvard University

In the stratosphere, aerosol particles would naturally disperse around -- and affect -- the entire planet. That's effective in climate terms, but potentially tricky in political terms. At a time of high environmental awareness, getting 195 nations to agree to inject lots of anything into the atmosphere could be a tough sell at best. 

Solar geoengineering

Aerosol injection of reflective particles could be accomplished from specially equipped aircraft or balloons.

Harvard University

But the concept may have the winds of natural history at its back: The volcanic eruption of Mt. Pinatubo in the Philippines in 1991 shot particles 22 miles into the sky where they lingered for a couple of years, cooling the Earth by nearly 1 degree, a huge shift in geoclimatic terms. Intentional solar geoengineering would seek to replicate that cooling without the toxic ash and rain that came with the eruption.

Mt. Pinatubo volcanic eruption

The 1991 eruption of Mt. Pinatubo was an inadvertent test case for using particles in the stratosphere to reduce the sun's energy on earth.


Even though climate change is often portrayed as a hastening crisis, Golja indicates the Harvard work is a "break glass in case of future emergency" technology. "There's an important difference between advocating for research and advocating for deployment," she says. "The research community is starting to wonder if there are key risks we can mitigate now to hand the next generation enough information if they get into a situation where they need to use this technology." 

Harvard's Colleen Golja shared many more insights into solar geoengineering with CNET's Brian Cooley, and you can hear a concise version of their full conversation in the video above.


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