Gravity isn't constant; it fluctuates across the Earth's surface, its strength affected by the rotation of the Earth and the presence of mountains and ocean trenches. And though these minor fluctuations aren't detectable as we travel from one area to another, they can be measured by satellites.
Measuring gravity is what GOCE (Gravity field and steady-state Ocean Circulation Explorer), one of the European Space Agency's many scientific satellites, has been doing for the last several years. Recently, a team of international scientists -- including researchers from the German Geodetic Research Institute, Germany's Technical University of Munich, the Netherland's Delft University of Technology, and NASA's Jet Propulsion Laboratory -- found the diminishing gravity directly mirrored ice loss along the West Antarctic Ice Sheet as a result of melting.
The NASA-Germany GRACE satellite mission also looks at gravity data to measure fluctuations in ice mass, but the measurements are much more crude. GOCE is able to measure gravity changes more exactly, with local specificity -- like changes among among small glacier features.
Of course, this new information is more intriguing than it is revelatory. ESA's CryoSat satellite is one of many high-tech instruments looking specifically at the lost of ice in West Antarctica. Still, the more angles there are from which to observe and analyze the loss of polar ice, the more likely scientists are to piece together the larger picture and long-term implications.
"We are now working in an interdisciplinary team to extend the analysis of GOCE's data to all of Antarctica," Johannes Bouman, a researcher with the German Geodetic Research Institute, said in a press release. "This will help us gain further comparison with results from CryoSat for an even more reliable picture of actual changes in ice mass."