Climate warming is changing how much water remains in Earth's greatest treasuries of ice and snow, NASA scientists have confirmed. The most comprehensive survey ever undertaken of the enormous ice sheets covering both Greenland and Antarctica shows a net loss of ice to the sea and projects that the Greenland ice sheet could be facing an irreversible decline by the end of the century.
The 10 year survey shows there was a net loss of ice from the combined polar ice sheets between 1992 and 2002 and a corresponding rise in sea level. The 20 billion net tons of water melted into the oceans each of those 10 years is equivalent to the amount of fresh water annually used in homes, businesses, and farming in New York, New Jersey, and Virginia.
The survey documented extensive thinning of the West Antarctic ice shelves, an increase in snowfall in the interior of Greenland, and thinning of ice at the edges.
"If the trends we're seeing continue and climate warming continues as predicted, the polar ice sheets could change dramatically," said survey lead author Dr. H. Jay Zwally of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The Greenland ice sheet could be facing an irreversible decline by the end of the century," Zwally warned.
Global average surface temperatures in 2005 were virtually identical with those of 1998 - the hottest year on record since 1880, the earliest year for which reliable instrumental records were available worldwide.
The record heat of 2005 is part of a longer term warming trend due to the rise of heat-trapping gases in Earth's atmosphere that is due to human activities - burning fossil fuels and clearing forests. Nineteen of the hottest 20 years on record have occurred since 1980.