NASA scientists have discovered that Antarctic snow has been melting further inland and at higher altitudes that over the past twenty years.

Antarctica holds 90% of the Earth’s fresh water and has a surface size of around 1.5 times the size of the United States (although much of the water is in a frozen state). Because of this, Antarctica is the largest potential source of rising sea levels as a result of global warming.

In the past, many have focused solely on the Artic ice melt, failing to look at Antarctica because summer temperatures rarely rise above freezing so little melt takes place. However NASA scientists have been looking at satellite data collected between 1987 and 2006 which showed that snow melt was occurring in some unlikely places – some snowmelt was occurring as far in as 500 miles from the coast, and some was 1.2 miles above sea level in the Transantarctic Mountains. In 2005 it was reported that there was some unusual melting throughout Antarctica and this latest data supports those findings.

The satellite data also shows that the Ross Ice Shelf is experiencing increased persistent snowmelt – both the duration and affected areas have increased (persistent snowmelt is melting that has occurred for either three days, or for one consecutive day and night).

However, snowmelt is not increasing across the whole of Antarctica and there are some areas which are actually experiencing less snowmelt than before. However many are worried because increased snowmelt in places such as the Ross Ice Shelf can lead to melt ponds on the surface of the ice. The water in these ponds can then filter into small cracks in the ice, pressurising them, and causing larger ice fractures. The Ross Ice Shelf itself acts as a ‘brake’ for glaciers so there is concern over the increased snowmelt in the area. Ice shelves tend to cover coastal land with extended areas floating on the sea. This keeps the warmer sea air at a distance from the glaciers, therefore helping to prevent melting acceleration.

It is unclear what is causing these snowmelt pattern changes, although many are pointing the finger at global warming.
 

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