A water truck heads up Colorado Road 215 along Parachute Creek. Water is key to extracting natural gas from deep underground. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

An artist's impression of a group of Yutyrannus. The 30-foot-long dinosaurs were covered with downy feathers — likely to keep the animals warm. Dr. Brian Choo/Nature hide caption

itoggle caption Dr. Brian Choo/Nature

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 hide caption

itoggle caption 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 hide caption

itoggle caption NASA Earth Observations

Towers carry electrical lines in San Francisco. The electricity grid is a web of power stations, transformers and transmission lines that span the continent. Justin Sullivan/Getty Images hide caption

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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. AFP/Getty Images hide caption

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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 hide caption

itoggle caption 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 hide caption

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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 hide caption

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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 hide caption

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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 hide caption

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An Indian street dweller prepares food on the streets of Kolkata. A growing number of scientists say that reducing black carbon — mostly soot from burning wood, charcoal and dung — would have an immediate and powerful impact on climate. Deshakalyan Chowdhury/AFP/Getty Images hide caption

itoggle caption Deshakalyan Chowdhury/AFP/Getty Images

With the skyline of Youngstown, Ohio, in the distance, a brine injection well owned by Northstar Disposal Services LLC is seen in Youngstown on Jan. 4. The company has halted operations at the well, which disposes of brine used in gas and oil drilling, after a series of small earthquakes hit the Youngstown area. Amy Sancetta/AP hide caption

itoggle caption Amy Sancetta/AP

In a double-blind test by professional violinists, most couldn't determine — by sound alone — which violin was an original Stradivarius and which was a modern instrument. Above, a 1729 Stradivari known as the "Solomon, Ex-Lambert." Don Emmert/AFP/Getty Images hide caption

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A Kemp's ridley sea turtle like this one traveled 4,600 miles across the Atlantic ocean in 2008. After being rehabilitated in Portugal, it is being reintroduced into its native Gulf of Mexico waters on Tuesday. US EPA via flickr hide caption

itoggle caption US EPA via flickr