Much has been made of Greenland’s ice cap melting faster lately. And the math is indisputable, if the entire ice cap melted, the earth’s oceans would rise a lot. Estimates vary, but we estimate 45 feet, which is somewhere in the middle of the spectrum of estimates. You can check our calculations for Greenland in paragraph three of our recent post Antarctic Ice.
So how much are current higher levels of ice melt in Greenland contributing to rising sea levels? According to Science Magazine’s article “Greenland Ice Sheet: High-Elevation Balance and Peripheral Thinning,” studies indicate “a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise sea level by 0.13 millimeter per year–approximately 7% of the observed rise.” If you do the math, Greenland’s current levels of melt (25.4 millimeters to the inch, .13 millimeters per year, 139 million square miles of ocean) will raise sea levels in the world by about 1/2 inch per century. Not much there.
So how much more ice is forecast to melt in Greenland in the near future? In a University of Texas report entitled “Greenland’s ice loss accelerating rapidly,” is the following: “The loss of ice has been occurring about five times faster from Greenland’s southeastern region in the past two years than in the previous year and a half. The dramatic changes were documented during a University of Texas at Austin study of Greenland’s mass between 2002 and 2005. The Greenland study, for example, suggests that the amount of fresh water contributed from the melting of its ice sheet could add 0.56 millimeters annually to a global increase in sea levels, higher than all previously published measurements.”
Sounds bad? Get out the calculator again. At .56 millimeters annually, we’re talking about 2.2 inches of sea level rise per century. Not much there either.
There is even evidence that increased snowfall, caused by global warming, will cause snow and ice to accumulate in Greenland’s interior, more than offsetting the increased melting on Greenland’s perimeter. According to NASA, in a report posted on their website entitled “Greenland’s Ice Thinning More Rapidly at Edges” they say “there is currently a debate between climate scientists over how global warming might affect ice in Greenland. Warm air has a higher capacity for holding water, and computer models show that as the Earth and the Arctic warm, there will be more precipitation falling from a wetter atmosphere. If more snow falls onto places like Greenland, it could offset the melting that takes place.”
The NASA information page goes on to say there has been record snowfalls in Greenland’s southeast: “While most of the coastal ice has thinned, ice thickened by about a meter (3.2 feet) between 2002 and 2003 in Southeast Greenland. The sudden thickening was due to some unusually large amounts of snowfall. While up to a meter of snowfall a year would not be out of the ordinary for the area, around 3 meters (9.8 feet) of snow fell between May 2002 and May 2003. Ice cores from nearby this area show that in last 100 years there has never been this much snowfall in a single year.”
This thickening of the ice in Greenland’s interior is corroborated by the European Space Agency. In “Warmer climate leads to more snow in Greenland? ” they report that “ESA scientists recently analyzed 11 years of radar altimetry data for the Greenland Ice Sheet from its ERS satellites, and came up with a remarkable find. While the edges of the Greenland Ice Sheet have thinned, the high-elevation interior has actually grown in thickness as much as 6 cm (nearly 2.5 inches) per year, for the years 1992-2003.”
They then say “Modelling studies of the Greenland Ice Sheet mass balance under greenhouse global warming have shown that temperature increases up to about 3ºC lead to positive mass balance changes at high elevations – due to snow accumulation – and negative at low elevations – due to snow melt exceeding accumulation. However after that threshold is reached, potentially within the next hundred years, losses from melting would exceed accumulation from increases in snowfall – then the meltdown of the Greenland Ice Sheet would be on.”
Well then, according to ESA scientists, we have 100 years before Greenland really starts to melt. And a century from now, why would a temperature increase of 3 degrees centigrade be sufficient to stop snowfall on the top of Greenland from accumulating faster than ice melts on the edges?
Before enacting dramatic new regulations to combat global warming, we are obligated to do our best to understand the facts and the logic surrounding these predictions, not just agree with whatever quotes reporters and lobbyists have parsed from the scientific community and packaged up for us.