Soon, ranchers like this one might be able to use their land to offset carbon emissions. Some are excited that they could use the land to earn a profit, while others don't want to invest in the idea just yet. Charlie Riedel/AP hide caption

itoggle caption Charlie Riedel/AP

SkyFuel unveiled last year one of the world's highest-performance, lowest-cost solar thermal power systems, in Arvada, Colo. Concentrated solar power, in which a large array of collectors concentrates a beam of energy to heat a fluid and run turbines, is viewed as a more likely source of large-scale electric power. Jack Dempsey/AP/SkyFuel hide caption

itoggle caption Jack Dempsey/AP/SkyFuel

Sunlight shines through a grove of redwood trees at the Muir Woods National Monument in Marin County in Northern California. Eric Risberg/AP hide caption

itoggle caption Eric Risberg/AP

Marine scientist Walter Boynton of the University of Maryland Center for Environmental Science is studying mud, ooze, and other material from the Chesapeake Bay's bottom to find out what areas are healthy and where it's dying. John Poole/NPR hide caption

itoggle caption John Poole/NPR

A snowy tree cricket feeds on a leaf from a mountain dalea plant. Gerardine Vargas hide caption

itoggle caption Gerardine Vargas