NASA Study - Gulf Of Alaska Area Small, But Equals Nearly Half Of Greenland's Freshwater Melt Volume

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A NASA-led research team has used satellite data to make the most precise measurements to date of changes in the mass of mountain glaciers in the Gulf of Alaska, a region expected to be a significant contributor to global sea level rise over the next 50-100 years.

Geophysicist Scott Luthcke of NASA's Goddard Space Flight Center, Greenbelt, Md., and colleagues knew from well-documented research that changes in the cryosphere – glaciers, ice caps, and other parts of the globe covered year-round by ice -- are a key source of most global sea level rise.

Melting ice will also bring changes to freshwater resources and wildlife habitat. Knowing that such ice-covered areas are difficult to observe consistently, the team worked to develop a satellite-based method that could accurately quantify glacial mass changes across seasons and years, and even discern whether individual glacier regions are growing or shrinking. The study's authors found that the annual ice mass lost from glaciers in the Gulf of Alaska has been 84 gigatons annually, about five times the average annual flow of the Colorado River through the Grand Canyon and equal to the entire amount of water in the Chesapeake Bay.

"The Gulf of Alaska region is 20 times smaller than the ice-covered area of Greenland, yet it contributes nearly half as much freshwater melt as Greenland and accounts for about 15 percent of present-day global sea level rise stemming from melting ice," said Luthcke, lead author of the study which will appear this week in the Journal of Glaciology. "Considering that the Gulf of Alaska makes such a disproportionate contribution, it is vital that we know more about the nature of glacial change there."

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