The Global Positioning System (GPS) helped scientists detect a staggering 100 billion tonnes of ice loss in Greenland over six months during 2010, according to a study. The team, led by earth scientists at Ohio State University, pinpointed a period in 2010 when high temperatures caused the natural ice flow out to sea to suddenly accelerate, with a staggering 100 billion tonnes of ice melting away from the continent in only six months.
The study points out the potential for GPS to detect many consequences of climate change, including ice loss, the uplift of bedrock, changes in air pressure – and perhaps even sea level rise, months, the journal Proceedings of the National Academy of Sciences reported. This method has been used to study ice loss before, in Antarctica as well as Greenland. But previously, GPS could only detect changes over a period of several years, said project leader Michael Bevis, Ohio Eminent Scholar in Geodynamics and professor in the School of Earth Sciences at Ohio State. While shortening the detection time to six months is a substantial advance, Bevis thinks his team will soon do even better. “Within the next year or so, we should be able to process the GPS data within a month of its being collected, and then we can monitor abrupt changes in ice mass only a month or two after they occur,” he said.
Scientists were able to make the measurement because the earth compresses or expands like a spring depending on the weight above it, letting them use the Greenland bedrock like a giant bathroom scale to weigh the ice atop it. As ice accumulates, the bedrock sinks, and as the ice melts away, the bedrock rises, said a university statement. Measurements revealed that Greenland sank by about six mm (about one quarter of an inch) over the winter of 2010, and the researchers determined that half of the sinking (three mm) was actually due to high air pressure above the ice, and the other half was due to ice accumulation. Further, they determined that the bedrock lifted 11 mm over the course the summer. Air pressure appeared to affect the bedrock less during this time, so that the bounce-back appears to be mostly due to ice loss.