Space mirrors? Flying “volcanoes”? Over at National Geographic, my pal Mason Inman presents five extreme geoengineering proposals to prevent a global warming catastrophe. The ideas were included in report from the United Kingdom’s Royal Society. From National Geographic:

Computer-controlled ships could ply the remote seas, pumping out seawater mist, which would encourage low, thick clouds to form, researchers say. The clouds would reflect sunlight back into space.

It would cost more than a billion dollars to launch a fleet of a few hundred of these ships, the new study says—a relatively small sum, as geoengineering costs go.
But the cloud ships’ ability to change local temperatures and weather could raise fears that countries will clash over control of the clouds…

Instead of trying to block sunlight via Earth’s atmosphere, another approach would be to take the fight to outer space.

Huge mirrors or thin, reflective disks could orbit alongside Earth and block solar rays, some scientists say.

The approaches would be safe, with little in the way of side effects, the Royal Society says.

But it could cost a few trillion dollars and take decades to design, build, and launch, requiring “a space program many times larger than anything yet attempted.”

“5 Last-Ditch Schemes to Avert Warming Disaster“