Snow melting in Greenland accelerating

Posted by Wolfgang Gruener

Greenbelt (MD) – A NASA sponsored study found that snow in Greenland is melting at an accelerated pace, potentially impacting the sea level and the Earth's energy budget how much radiation from the sun is absorbed by the Earth versus that reflected back into the atmosphere.

Marco Tedesco, a research scientist at the Joint Center for Earth Systems Technology, said that snow melting in Greenland has reached a new record high for high-altitude areas over 1.2 miles above sea level. In some cases, melting jumped by 150% above normal levels, which translates in melting periods that are 25 to 30 days longer than the average of previous years since 1988.

 

 

Tedesco said that that he collected data highlighting the snow melting in Greenland by using the capabilities of the "Special Sensor Microwave Imagers" of the Defense Meteorological Satellite Program. Satellites passing Greenland were able to measure how much of an electromagnetic signal was naturally emitted by snow and ice in areas beneath. While certain areas showed a record pace in snow melting, the 2007 result is the fifth highest, after 2005, 2002, 1998 and 2004, in the 19-year history of the program. Tedesco said that the melting acceleration for high-altitudes came as a surprise, as initial "melting in April and May of this year in high-altitude areas was very low."

However, June melting jumped unexpectedly and resulted in a record melting index for the year. The melting index is determined by multiplying how long melting took place by the area where the increased melting took place.

"When snow melts at those high altitudes and then refreezes, it can absorb up to four times more energy than fresh, unthawed snow," said Tedesco. "This can affect Earth's energy budget by changing how much radiation from the sun is absorbed by the Earth versus that reflected back into the atmosphere. Refrozen snow can also alter the snow density, thickness and snow-water content."

According to the scientist, the snow melting also impacts sea level rise on multiple levels. "Increases in the overall melting trend over Greenland have an impact that stretches beyond its icy shores," said Tedesco. "Aside from contributing to direct sea level rise, melting especially along the coast can speed up glaciers since the meltwater acts like a lubricant between the frozen surface and the bedrock deep below. The faster glaciers flow, the more water enters the ocean and potentially impacts sea level rise."