In 2002, an immense, 200-meter-thick ice shelf the size of Manhattan collapsed into the ocean off the Antarctic Peninsula, shocking scientists and raising the alarming possibility that we may be heading toward an ice-free Antarctica, last seen a million years ago. That would raise world sea levels so high that New York City would be flooded up to the level of the Statue of Liberty's shoulders. But could this really happen? Is Antarctica's surprising...

The cryosphere has a global reach, extending beyond the polar regions. It consists of those parts of the Earth's surface where water is found in solid form, including areas of snow, sea ice, glaciers, permafrost, ice sheets, and icebergs. NASA Earth observing satellites are providing scientists with unparalleled insight into how the cryosphere behaves, how it is changing, and what implications whose changes have on the Earth's global systems, including...