Ice Caps and Glaciers Contend for Biggest Loser Award
There are few things on Earth that have undergone a more dramatic weight loss than the world's ice caps and glaciers. According to a recent study, they have lost about 150 billion tons per year from 2003 to 2010. Such a large quantity of ice has translated to a 0.4 millimeter rise in sea levels each year. At this rate, it will take 2,500 years for sea levels to rise one meter. However, indications point towards accelerated ice loss in the future. Plus, if including ice lost from the major land-based ice sheets, sea level rise is much worse.
Loss of ice from the fringes of Greenland and Antarctica contributed an additional 80 billion tons. Altogether, the researchers estimate that sea level rise, caused by loss of all ice on Earth between 2003 and 2010, is equivalent to adding 8 times the volume of Lake Erie into the oceans.
The research was conducted by a team at the University of Colorado-Bouler. They used data from the twin Gravity Recovery and Climate Experiment (GRACE) satellites, a joint project between NASA and scientists in Germany. These satellites circle the globe in tandem 16 times per day, sensing even the slightest variation in the planet's mass and gravitational pull.
"This is the first time anyone has looked at all of the mass loss from all of Earth's glaciers and ice caps with GRACE," said CU-Boulder physics Professor John Wahr. "The Earth is losing an incredible amount of ice to the oceans annually, and these new results will help us answer important questions in terms of both sea rise and how the planet's cold regions are responding to global change."
Total ice loss on Earth from 2003 to 2010 was calculated at about 1,000 cubic miles. To put that in context, Wahr explains that this amount "would cover the entire United States in about 1 and one-half feet of water."
Data from the GRACE satellites show that sea level rose 12 millimeters (1.5 inches) from 2003 to 2010. This rise is partly caused by ice loss. The other major factor is expansion due to rising water temperatures. The water expansion component is believed to be roughly equal to the ice melt component.
"One big question is how sea level rise is going to change in this century," said co-author, Professor Tad Pfeffer. "If we could understand the physics more completely and perfect numerical models to simulate all of the processes controlling sea level -- especially glacier and ice sheet changes -- we would have a much better means to make predictions. But we are not quite there yet."
The study was published in the journal, Nature.
Ice Melting image via Shutterstock