Researchers say that springtime snow is melting in the Arctic even faster than Arctic ice. That means less sunlight is reflected off the surface. Bare land absorbs more solar energy, which can contribute to rising temperatures on Earth. Above, a musher races along the Iditarod in the Alaskan tundra in 2007.
A man stands in a fountain in Washington Square Park on July 18, in New York City. Temperatures were expected in the upper 90's during another heat wave in the city.
Mario Tama/Getty Images
The Larsen B ice shelf, a large floating ice mass on the eastern side of the Antarctic Peninsula, shattered and separated from the continent 10 years ago. A NASA satellite captured the event in this image from Feb. 23, 2002. The 650 foot-thick, 1,250-square-mile ice shelf had existed since the last ice age.
Muslim girls study by candlelight inside a religious school in Noida, near New Delhi, on July 31. The collapse of three regional power grids last week caused a massive power outage that blacked out more than half of India.
Parivatran Sharma/Reuters /Landov
This algae, called Chaetoceros atlanticus, can bloom in the ocean when iron is added to the water. It captures carbon dioxide from the atmosphere and carries the carbon down underwater when it sinks.
Marina Montresor, SZN/Alfred Wegener Institute