They are found to be lower than first estimated

Mar 3, 2010 07:28 GMT  ·  By

A group of researchers has recently determined that the rate at which a major portion of Alaskan glaciers is melting has been exaggerated by previous studies. The experts note that the method of calculation they used show that the actual melt rate is about 66 percent of the initially-established one. The team adds that, although these particular glaciers may contribute slightly less to rising sea levels than thought, those in Antarctica, the Arctic and Greenland still pose a major threat to the safety of coastal communities, PhysOrg reports.

The rate at which glaciers melt in Alaska was analyzed for a period of time spanning several decades, between 1962 and 2006. The investigation was conducted by researchers from the Laboratory for Space Studies in Geophysics and Oceanography at the University of Toulouse, in France, who were led by experts Etienne Berthier. Details of their investigation appear in the February issue of the respected scientific publication Nature Geoscience. The paper was coauthored by Northern Arizona University geographer Erik Schiefer, who says that the new study merely refines previous calculations, and is not meant to be used by people promoting the idea that global warming is not happening.

The group established that the rate of melting in Alaskan glaciers is contributing by about .0047 inches to the global sea level rise per year, a figure that is smaller than the .0067 inches originally established. Although these numbers may seem extremely small, and therefore negligible, Schiefer says that the amounts add up over the decades. In addition, Alaskan glaciers are nowhere near those at the poles, or in Greenland, in terms of importance in contributing to sea level rise. “We're also talking about a small proportion of ice on the planet. When massive ice sheets (such as in the Antarctic and Greenland) are added in, you're looking at significantly greater rates of sea-level rise,” the expert adds.

The team acknowledged that glacier ice loss has accelerated over the past two decades considerably. Schiefer says, “With current projections of climate change, we expect that acceleration to continue.” For the study, the group used datasets collected by the French satellite SPOT 5, and also by the NASA/Japanese ASTER satellite. They then compared these readings to topographical maps depicting glacier elevations kept on record since the 1950s, and determined that this difference exists. In the future, they say, satellite studies may provide us with the necessary information to develop more accurate and informed computer models to predict the evolution of global warming.