An excerpt from Bloomberg:
To scientists who study geoengineering, this is within the realm of possibility. The idea is to manipulate the climate, by planting millions of trees to clear the air or -- at the other extreme -- creating a mirror of chemicals in the heavens to reflect the sun’s heat away from Earth. Some of the schemes are outlandish, if not downright scary. A small though increasingly vocal band of experts in the field contends the options must at least be explored.