CU-Boulder study shows global glaciers, ice caps shedding billions of tons of mass annually

I've linked to news coverage of this study before, but here's the authoritative account without the denialist spin that some news outlets have been pushing as a result of less than expected ice losses in high Asia mountains: University of Colorado at Boulder: Earth’s glaciers and ice caps outside of the regions of Greenland and Antarctica are shedding roughly 150 billion tons of ice annually, according to a new study led by the University of Colorado Boulder.

The research effort is the first comprehensive satellite study of the contribution of the world’s melting glaciers and ice caps to global sea level rise and indicates they are adding roughly 0.4 millimeters annually, said CU-Boulder physics Professor John Wahr, who helped lead the study. The measurements are important because the melting of the world’s glaciers and ice caps, along with Greenland and Antarctica, pose the greatest threat to sea level increases in the future, Wahr said.

The researchers used satellite measurements taken with the Gravity Recovery and Climate Experiment, or GRACE, a joint effort of NASA and Germany, to calculate that the world’s glaciers and ice caps had lost about 148 billion tons, or about 39 cubic miles of ice annually from 2003 to 2010. The total does not count the mass from individual glacier and ice caps on the fringes of the Greenland and Antarctic ice sheets -- roughly an additional 80 billion tons.

“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 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.”

...“The total amount of ice lost to Earth’s oceans from 2003 to 2010 would cover the entire United States in about 1 and one-half feet of water,” said Wahr, also a fellow at the CU-headquartered Cooperative Institute for Research in Environmental Sciences.

The vast majority of climate scientists agree that human activities like pumping huge amounts of greenhouse gases in the atmosphere is warming the planet, an effect that is most pronounced in the polar regions.

One unexpected study result from GRACE was that the estimated ice loss from high Asia mountains -- including ranges like the Himalaya, the Pamir and the Tien Shan -- was only about 4 billion tons of ice annually. Some previous ground-based estimates of ice loss in the high Asia mountains have ranged up to 50 billion tons annually, Wahr said.

...“What is still not clear is how these rates of melt may increase and how rapidly glaciers may shrink in the coming decades,” said Pfeffer, also a professor in CU-Boulder’s civil, environmental and architectural engineering department. “That makes it hard to project into the future.”

...“One big question is how sea level rise is going to change in this century,” said 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.”...