GRACE's Measurements
Using a specially developed data filtering technique, Chen's team has been able to calculate the ice mass lost in Greenland.
The GRACE mass measurements show 69 percent of the recent ice loss came from eastern Greenland. Out of the 57 cubic miles (239 cubic kilometers) of water added to the sea on average per year, 39 cubic miles (164 cubic kilometers) spilled out from the eastern coast. Of that amount, more than 50 percent came from ice from glacier in southeast Greenland, the researchers reported.
GRACE measures the mass changes from ice and water movements by using twin satellites that keep a very close watch on each other to detect the slightest gravitational bumps on any portion of their subject planet.
Since water has a lot of mass, and all mass exerts gravitational force, the twin GRACE satellites have been able to provide unprecedented measurements over the past few years of not only ice changes, but even seasonal changes in water from land to seas.
The satellite studies are confirming and extending the work of ice researchers who have been seeing dramatic changes recently in Greenland's glaciers. The work has made clear that there is a glaring flaw in all the climate models used to predict climate change: they have traditionally treated Greenland and Antarctica like large blocks of ice that slowly melt, explained Hamilton.
What's happening in Greenland now shows that the glaciers can apparently hit a climate threshold and disintegrate rapidly, not at all like a giant ice cube, he said.
The new GRACE work has also underscored at least one other flaw in all the climate models used to predict climate change: They have not included sudden changes in glaciers, said Eric Rignot, leader of the JPL study.
It's also not something that modelers are going to solve very quickly, Rignot added.
"It's not like they have another model up their sleeves," said Rignot.
In order to put glaciers in the models, they need to understand exactly how glaciers work, something nobody is certain about right now, he said.
