1. Artificial VolcanoesCan we combat climate change by changing the climate? It's worth a try, say advocates of geoengineering—manipulating the climate to reduce the effects of heat-trapping greenhouse gases in Earth's atmosphere. (See: "5 Last-Ditch Schemes to Avert Warming Disaster.")One such potential fix is dubbed artificial volcanoes, or pumping bits of sulfur—an ingredient from volcano ash that becomes a gas—into the atmosphere. Like ash from real volcanoes, (pictured, a volcano erupts on Iceland's Heimaey Island), the particles bounce the sun's light and heat back into space.This and other emergency measures are under the microscope this week as part of the first Asilomar International Conference on Climate Intervention Technologies in Pacific Grove, California. The meeting will attempt to draft the world's first voluntary guidelines for ethical behavior in geoengineering schemes, most of which are still no more than ideas.That's not to say any of the schemes will be deployed in the near future, noted Samuel Thernstrom, co-director of the Geoengineering Project at the American Enterprise Institute, a Washington, D.C.-based policy-research institute.But experts should seriously consider all options, Thernstrom said, including altering the climate: "There is no argument for ignorance—we should know more about geoengineering."—Christine Dell'Amore

Photograph by Emory Kristof, National Geographic