A 2008 view of the leading edge of the Larsen B ice shelf, extending into the northwest part of the Weddell Sea. Huge, floating ice shelves that line the Antarctic coast help hold back sheets of ice that cover land. Mariano Caravaca /Reuters/Landov hide caption

itoggle caption Mariano Caravaca /Reuters/Landov

An earlier spring in Montana's Glacier National Park means full waterfalls at first — but much drier summers. Robert Glusic/Corbis hide caption

itoggle caption Robert Glusic/Corbis

A new study suggests the Greenland Ice Sheet did not fully melt during previous periods of global warming — and that it preserved a tundra beneath it. Joshua Brown/ University of Vermont hide caption

itoggle caption Joshua Brown/ University of Vermont

The small patch in the middle of the image is Aulacomnium turgidum, a type of bryophyte plant. Researchers in the Canadian Arctic say they are surprised the bryophytes were still green, even after being covered by ice. Courtesy of Caroline La Farge hide caption

itoggle caption Courtesy of Caroline La Farge