Climate Fact: GRACE and GPS Ice Mass Update
In Brief: The area of ice mass loss on the Greenland ice sheet has been migrating northward since 2005.
As large ice sheets melt and lose weight, the underlying crust “uplifts” or “rebounds” in response. Researchers have been using two key tools to monitor the rates of ice loss on the Greenland Ice Sheet: a) GPS stations located on bedrock next to the ice and b) twin satellites that are part of the Gravity Recovery and Climate Experiment (GRACE). The GPS data monitor uplift directly, but each GPS station can only tell you about the uplift taking place in a local area. Data from GRACE, on the other hand, which uses Newton’s Laws of Gravity to monitor changes in Earth’s mass distribution, can predict crustal uplift by measuring ice mass losses averaged over hundreds of miles. Taken together, these two data sets suggest that the rates of ice mass loss in southeast Greenland are faster now than they were before 2003, a year when destabilizations on the ice sheet likely occurred. Although the rates of ice sheet loss stabilized there by 2006, these glaciers are still contributing more ice to the oceans that they were in the late 1990s and early 2000s. While most of the ice mass loss had been limited to the southern portion of the contienent before 2005, the area where noticeable melting and discharge occurs has been moving north along Greeland’s west coast since that year. Since 2007, the northwest corner of the ice sheet has been shrinking.
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Source: Khan, SA et al. “Spread of ice mass loss into northwest Greenland observed by GRACE and GPS.” Geophysical Research Letters 37 (2010): L06501.
