MIT Technology Review reports:
David Mitchell, a lanky, soft-spoken atmospheric physicist, believes frigid clouds in the upper troposphere may offer one of our best fallback plans for combating climate change... Fleets of large drones would crisscross the upper latitudes of the globe during winter months, sprinkling the skies with tons of extremely fine dust-like materials every year. If Mitchell is right, this would produce larger ice crystals than normal, creating thinner cirrus clouds that dissipate faster. "That would allow more radiation into space, cooling the earth," Mitchell says...
Increasingly grim climate projections have convinced a growing number of scientists it's time to start conducting experiments to find out what might work. In addition, an impressive list of institutions including Harvard University, the Carnegie Council, and the University of California, Los Angeles, have recently established research initiatives... By this time next year, Harvard professors David Keith and Frank Keutsch hope to launch a high-altitude balloon from a site in Tucson, Arizona. This will mark the beginning of a research project to explore the feasibility and risks of an approach known as solar radiation management. The basic idea is that spraying materials into the stratosphere could help reflect more heat back into space, mimicking a natural cooling phenomenon that occurs after volcanoes blast tens of millions of tons of sulfur dioxide into the sky.
"I don't really know what the answer is," says a former associate director at Lawrence Livermore National Laboratory. "But I do believe we need to keep saying what the truth is, and the truth is, we might need it."
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