May 16 (Bloomberg) -- Snow melted across an area of western Antarctica the size of California in 2005 as a result of warmer temperatures, the National Aeronautics and Space Administration said, citing data recorded by a satellite.

``Increases in snowmelt, such as this in 2005, definitely could have an impact on larger scale melting of Antarctica's ice sheets if they were severe or sustained over time,'' said Konrad Steffen, of the University of Colorado, according to NASA'S Web site. ``Large regions are showing the first signs of warming.''

Water from melted snow can penetrate ice sheets through cracks and lubricate the base of the formations ``causing the ice mass to move toward the ocean faster, increasing sea level,'' said Steffen, the director of the university's Cooperative Institute for Research in Environmental Studies.

Antarctica's ice mass is the world's largest fresh water reservoir and large amounts of water flowing into the ocean may affect the salinity, currents and global climate, NASA said. No further melting has been detected through to March this year, the agency said.

The melting in 2005 was mapped by NASA's QuikScat craft and is the ``most significant melt observed using satellites in the past three decades,'' NASA said on its Web site.

The melting snow created an ice layer where water refroze and the thawing wasn't prolonged enough for water to flow into the sea, it said.

High Altitude

The change was observed in areas as far as 560 miles (900 kilometers) inland and higher than 6,600 feet above sea level, where such a thaw was considered to be unlikely, NASA said. The data was processed from July 1999 to July 2005.

While no further melting has been detected, more monitoring is needed, Son Nghiem, of NASA's Jet Propulsion Laboratory, said, according to the agency. He led the team assessing the data along with Steffen's researchers.

``Satellite scatterometry is like an X-ray that sees through snow and finds ice layers beneath as early as possible,'' he said. ``It is vital we continue monitoring this region to determine if a long term trend may be developing.''

Greenhouse gases that cause global warming can by kept in check by using available technologies and strategies, a United Nations panel said this month.

Keeping concentrations of the gases in the air at current levels will cost less than 3 percent of world economic output by 2030, the UN Intergovernmental Panel on Climate Change said in a May 4 report.

Rising temperatures will cause increased floods and droughts and extinctions of species, the panel said in an earlier report this year.

To contact the reporter on this story: Paul Tighe in Sydney at ptighe@bloomberg.net

Last Updated: May 16, 2007 00:05 EDT