Desperate to find a way to combat climate change, some scientists are proposing off-the-wall fixes, like making a Styrofoam continent about the size of North America that would float in the South Pacific and counteract global warming by reflecting sunlight into space. The idea is ludicrous, of course, says Michael MacCracken of the U.S. Global Change Research Program, but it makes the point that dramatic steps must be taken. Somewhat less bizarre proposals include injecting carbon dioxide (CO2), the most significant greenhouse gas, deep in the ocean or under the seabed; seeding certain ocean areas with iron to create blooms of plankton, which soak up CO2; planting vast numbers of trees to absorb CO2 ; and convincing farmers to plow their fields less frequently so plants can trap more CO2 underground.