The summer of 2005 saw enough snow to cover the whole of California melt from the face of our coldest continent.

According to NASA, this was the first widespread Antarctic melting ever spotted with its QuikSat satellite.

Researchers checked through data for snow accumulation and melt starting in 1999, through to 2005 [looking for the much anticipated Y2K meltdown? - Ed]. They found evidence of melting as much as 560 miles inland, and at altitudes that melting had not been expected.

The satellite takes advantage of the fact that snow, when it melts, refreezes as ice. The satellite's scatterometer uses radar pulses to scan the surface of the ice sheet. It can pick out the particular signature of refrozen snow and map the pattern of melting.

The summer in question was exceptionally warm, with air temperatures reaching as high as 5°C, and staying above melting point for more than a week at a time. It was warm enough to create an extensive ice layer, but not so warm, or prolonged, that the melt water had a chance to run off into the sea. Nonetheless, the researchers argue that the findings are significant.

Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado said that although warming in the far south has so far been confined to the Antarctic peninsula, the QuikSat data suggests this is changing.

He said: "Increases in snow-melt, 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.

"Water from melted snow can penetrate into ice sheets through cracks and narrow, tubular glacial shafts called moulins," he added. "If sufficient melt water is available, it may reach the bottom of the ice sheet. This water can lubricate the underside of the ice sheet at the bedrock, causing the ice mass to move toward the ocean faster, increasing sea level." ®

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