2 trillion tonnes of ice have melted since 2003: NASA

WASHINGTON: More than two trillion tonnes of land ice in Greenland,
Antarctica and Alaska have melted since 2003, according to new NASA
satellite data that show the latest signs of what scientists say is
global warming.More than half of the loss of landlocked ice in the
past five years has occurred in Greenland, based on measurements of
ice weight by NASA's GRACE satellite, said NASA geophysicist Scott
Luthcke.NASA scientists planned to present their findings on Thursday
at the American Geophysical Union conference in San Francisco. Mr.
Luthcke said Greenland figures for the summer of 2008 aren't complete
yet, but this year's ice loss, while still significant, won't be as
severe as in 2007.The news was better for Alaska. After a precipitous
drop in 2005, land ice increased slightly in 2008 because of large
winter snowfalls, Mr. Luthcke said. Since 2003, when the NASA
satellite started taking measurements, Alaska has lost 400 billion
tonnes of land ice.In assessing climate change, scientists generally
look at several years to determine the overall trend.Melting of land
ice, unlike sea ice, increases sea levels very slightly.In the 1990s,
Greenland didn't add to world sea level rise; now that island is
adding about half a millimetre of sea level rise a year, NASA ice
scientist Jay Zwally said in a telephone interview from the
conference.Between Greenland, Antarctica and Alaska, melting land ice
has raised global sea levels about one-fifth of an inch in the past
five years, Mr. Luthcke said. Sea levels also rise from water
expanding as it warms.Other research, being presented this week at the
geophysical meeting point to more melting concerns from global
warming, especially with sea ice."It's not getting better; it's
continuing to show strong signs of warming and amplification," Mr.
Zwally said. "There's no reversal taking place."

The Hindu, 17th December 2008