Christopher JoyceChristopher Joyce is a correspondent on the science desk at NPR. His stories can be heard on all of NPR's news programs, including NPR's Morning Edition, All Things Considered, and Weekend Edition.
A wobbling of the Earth on its axis about 20,000 years ago may have kicked off a beginning to the end of the last ice age. Glaciers in the Arctic and Greenland began to melt, which resulted in a warming of the Earth, a new study says. Above, Greenland's Russell Glacier, seen in 1990.
Veronique Durruty/Gamma-Rapho/Getty Images
This NASA map shows the size of aerosol particles in the atmosphere. Green areas indicate larger, more naturally occurring particles like dust. Red areas indicate smaller aerosol particles, which can come from fossil fuels and fires. Yellow areas indicate a mix of large and small particles.
NASA Earth Observations
A liquefied natural gas tanker arrives at a gas storage station east of Tokyo on April 6, 2009. The shuttering of Japan's nuclear power plants has driven an increased reliance on natural gas and other fossil fuels.
Steam rises from the cooling towers of nuclear reactors at Georgia Power's Plant Vogtle in Waynesboro, Ga. The U.S. Nuclear Regulatory Commission approved Southern Co.'s application to begin full construction of the nation's first new nuclear units since 1978 at Plant Vogtle.
Mary Ann Chastain/AP
Nonnative pythons, like this one, are invading the Florida Everglades. As a top predator, the snakes have crippled the populations of rabbits, raccoons and other animals.
Joe Raedle/Getty Images
Without a centralized national repository for nuclear waste, the radioactive material is currently being kept at various sites across the country. Above, large concrete canisters, each holding 14 55-gallon drums of waste, are loaded on a truck in 2005 in Richland, Wash., where they were later shipped to a facility in New Mexico.
Jeff T. Green/Getty Images
Hydraulic fracturing wells have been producing a tremendous amount of natural gas — far more than the current demand. Above, a Cabot Oil & Gas natural gas drill at a fracking site in South Montrose, Pa.
Spencer Platt/Getty Images
Contractors with SunEdison install more than 1,000 Chinese-made solar panels on top of a Kohl's Department Store in Hamilton Township, N.J., in 2010. Energy generated by the solar system will cut the store's usage, on average, by 25 to 30 percent.
Robert Nickelsberg/Getty Images