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

February 8, 2012

Feb. 8, 2012               John Wahr

A team of CU-Boulder scientists have completed the first comprehensive satellite study of the world’s glaciers and ice caps outside of Greenland and Antarctica and have found these regions are shedding roughly 150 billion tons of ice annually. The research team used satellite data gathered from the Gravity Recovery and Climate Experiment, or GRACE, for the study, says physics professor John Wahr (Waar).

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Feb. 8, 2012                                                                                                            John Wahr

A team of CU-Boulder scientists have completed the first comprehensive satellite study of the world’s glaciers and ice caps outside of Greenland and Antarctica and have found these regions are shedding roughly 150 billion tons of ice annually. The research team used satellite data gathered from the Gravity Recovery and Climate Experiment, or GRACE, for the study, says physics professor John Wahr (Waar).

CUT 1 “What Grace shows is the total loss between January 2003 and December 2010 is 148 billion tons per year. In general, GRACE can see changes in the mass distribution of the Earth at a few hundred kilometers scales anyway. (:17) And usually the signals that they can see generally come with a transportation of mass – the movement of water from one place to another.” (:27)

Although the research team counts on GRACE to portray crucial data for the study, Wahr, who helped lead the study, says there are some limitations to the dual satellite system. 

CUT 2  “The strength of Grace is that it sees the whole system. It sees it all.  The weakness of Grace is we do not have the resolution to look at individual glaciers themselves.  We can’t tell whether the mass loss is coming from this glacier or this glacier next to it, or that glacier next to that.“ (:13)

Wahr and his team calculated that ice loss from Greenland, Antarctica and the world’s glaciers and ice caps totaled about 1,000 cubic miles from 2003 to 2010, roughly eight times the water volume of Lake Erie.   

CUT 3 “All of Greenland and Antarctica during the same time period lost 384 billion tons per year, which is a little bit more than twice as much as the other mountain glacier and ice caps. (:13) Back when we started GRACE it wasn’t at all clear that Greenland and Antarctica were going to be big mass loss regions.” (:20)

Sea level rise is one of the main concerns of the ice cap and glacier mass loss in terms of global warming.  But GRACE’s data shows only ice loss to the oceans, which is only one component of sea level rise.

CUT 4 “Sea level rise has two general sources: one is just the ocean gets hot and expands and it has nothing to do with adding mass to the ocean but that’s a very real comport of sea level rise.  The other comport is the amount of mass that is actually getting pushed and shoved into the ocean from things like glacier melting and Antarctica and Greenland melting and so forth. (:20) And that’s the part that GRACE can really determine the sea’s mass.  If the ocean just get’s hot and expands there’s no extra mass in that and GRACE doesn’t see any of that.” (:29)

GRACE was launched in March 2002, and is still going strong. It has proven to be an important tool for the CU-Boulder research team but now the concern is how much longer will it last. 

CUT 5 “It was originally supposed to be a five year mission so we should have been gone years ago but it’s going strong now. It’s unclear how long it will last. (:09) There has in the meantime been approval for the launch of a GRACE follow up mission.  NASA is teaming up again with the German Space Agency, that’s who launched GRACE.  And that’s supposed to be launched at the end of 2016 to the start of 2017.” (:25) 

In the meantime, Wahr and his team will continue to monitor GRACE’s measurements and uncover any future glacier and ice cap mass loss results. 

-CU-

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