Sunday, April 10, 2011

Continued loss of Greenland and Antarctic Ice Sheets

Dr. Rignot and his colleagues from the University of California, Urvine have been measuring changes in the mass of the land-based ice sheets in Greenland and the Antarctic.  They have reported their findings in the scientific publication Nature Geoscience.

The current understanding of the process of climate warming in Greenland and the Antarctic suggests that snowfall may increase in the continents' interiors and, at the same time, accelerate melting on the coasts on account of the warmer air and ocean temperatures.  To further elucidate this mechanism, the team utilized highly sophisticated satellite radar observations between the years 1992 and 2006 covering 85% of Greenland's and Antarctica's coastlines to estimate the total mass movement of melt water into the ocean. 

Collecting this kind of information was once an extremely daunting task due to limitations in the ability to measure such intricate changes.  The technological advances over the past decades, however, have made it possible to measure trends on a monthly basis.  The results of such continuous observations demonstrate that the rate of the combined loss of the ice sheet has indeed increased and accelerated over the last eighteen years by a total of 36.3 Gigatons (Gt) per year.  A Gt is equivalent to 1 billion tons.   This rate is some three times faster than rate of ice melting in mountain glaciers and at the polar ice caps.  Should this rate of loss of land-bound ice continue unabated, it would prove to be the largest contributor to the ineluctable rise in the sea level by the end of this century.  This is not taking into account the distinct possibility that the rate of increase in atmospheric greenhouse gases as a result of human activity will increase over the coming decades.  According to Dr. Rignot, "Changes in glacier flow therefore have a significant, if not dominant impact on ice sheet mass balance."

This is a significant and troubling finding that adds yet another dimension to the disturbing prospects posed by the ever escalating concentration of greenhouse gases in the earth's environment.  Hopefully, the human community will use these kinds of data to implement policies that will ensure a tangible decrease in the actual use of fossil fuels to propel national economies.

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