The CO2 Prize

There's the man-made "volcano" that shoots gigatons of sulfur high into the air. The space "sun shade" made of trillions of little reflectors between Earth and sun, slightly lowering the planet's temperature. The forest of ugly artificial "trees" that suck carbon dioxide out of the air. And the "Geritol solution" in which iron dust is dumped into the ocean.

"Of course it's desperation," said Stanford University professor Stephen Schneider. "It's planetary methadone for our planetary heroin addiction. It does come out of the pessimism of any realist that says this planet can't be trusted to do the right thing."

NASA is putting the finishing touches on a report summing up some of these ideas and has spent $75,000 to map out rough details of the sun shade concept. One of the premier climate modeling centers in the United States, the National Center for Atmospheric Research, has spent the last six weeks running computer simulations of the man-made volcano scenario and will soon turn its attention to the space umbrella idea.

And last month, billionaire Richard Branson offered a $25 million prize to the first feasible technology to reduce carbon dioxide levels in the air.