A team of scientists from NASA's Jet Propulsion Laboratory in Pasadena, California, and the University of Colorado said new satellite imagery had revealed a vast expanse of snow melt in 2005 where it had previously been considered unlikely.

The NASA statement described the findings as "the most significant melt observed using satellites during the past three decades."

Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, said it was the first time melting on such a scale had been detected.

"Antarctica has shown little to no warming in the recent past with the exception of the Antarctic Peninsula, but now large regions are showing the first signs of the impacts of warming," said Steffen.

"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."

The melting occurred in multiple areas, including far inland, at high latitudes and high elevations, where melt had once been considered unlikely.

The melting was discovered using satellite scatterometry, a sophisticated imaging system which is able to distinguish between recently frozen ice or snow from snow that has been frozen for years.

The 2005 melt was intense enough to create an extensive ice layer when water refroze after the melt, the statement said. However, the melt was not prolonged enough for the melt water to flow into the sea.

Steffen said water from melted snow could penetrate ice sheets through cracks and glacial shafts known as moulins, which can cause the ice mass to slip and move toward the ocean faster.

Son Nghiem, of NASA's Jet Propulsion Laboratory, said while no further melting had been detected through March this year, more monitoring is needed.

"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."

The full results from the study "Snow Accumulation and Snowmelt Monitoring in Greenland and Antarctica," appears in a recently published book "Dynamic Planet," the statement added.

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