More Evidence Points To Greenland Tipping Point

An iceberg in the Tasiilaq harbor in East Greenland in 2005.

Photo: Sebastian H. Mernild

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Another study adds weight to the conclusion that Greenland's ice sheet is melting faster than predicted by the United Nations, and that sea level could rise faster than predicted around the world.

The International Polar Year study, by Sebastian H. Mernild of the University of Alaska-Fairbanks, was published in Hydrological Processes.

Mernild's team's model showed a doubling of freshwater runoff, in the form of melting and iceberg calving, from Greenland by the end of this century.

That level of melting would result in an annual rise of sea levels 45% greater than previously predicted – 1.6 millimeters a year, rather than 1.1. Another recent study predicted that sea levels would rise two times as fast as previously thought because of the rapid melting of Greenland.

Other recent research suggests a total melting of Greenland's ice sheet – which could take hundreds, or even 1,000 years – would make sea levels rise 23 feet.

This is only the latest study to show the effects of global warming are occurring at rates that exceed the predictions by the U.N. Intergovernmental Panel on Climate Change. While that panel is considered the scientific authority on the subject, its results are proving to be conservative in some areas, particularly the Arctic, which is responding first and most dramatically to climate change.

NASA Earth Observatory
This map shows the number of days Greenland experienced melting in 2007, relative to the preceding 19 years. Red indicates 30 days of additional melting. Areas of less melting are scarce, and shown in shades of blue.

Other recent research has shown that Greenland is melting faster than at any point in the last half century, and how a little melting goes a long way, because meltwater infiltrates cracks and speeds the loss of mass from the ice sheet, and because the loss of floating ice exposes darker water, which absorbs more heat and fuels a cycle of melting.

The melting of Greenland's ice sheet is viewed as one of 9 tipping points that should be avoided in order to avoid the worst consequences of global warming.

Here's a look at the National Wildlife Federation's exploration of Greenland:

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