An oil and gas facility in Roger Mills County in far-western Oklahoma. The governor is warning state agencies that low oil prices could stall the state economy. Joe Wertz/StateImpact Oklahoma hide caption

itoggle caption Joe Wertz/StateImpact Oklahoma

An excavator loads a truck with oil sands at the Suncor mine near the town of Fort McMurray in Alberta, Canada in 2009. Environmental groups that oppose oil sands mining have pointed to delayed and canceled projects as a sign of recent success. Mark Ralston/AFP/Getty Images hide caption

itoggle caption Mark Ralston/AFP/Getty Images

U.S. gasoline prices have fallen sharply since last summer, driven by surging oil production and other factors. The price for a barrel of U.S. West Texas Intermediate crude fell below $50 Monday. David N. Goodman/AP hide caption

itoggle caption David N. Goodman/AP

Water vapor, which looks like smoke, is seen rising from a power plant near Hengshui in China's Hebei province. In November, President Obama announced a landmark carbon-cutting deal with China — the world's leading producer of greenhouse gases. And the Chinese government has announced plans to cap the use of coal within five years. Fred Dufour/AFP/Getty Images hide caption

itoggle caption Fred Dufour/AFP/Getty Images