Too early to Draw Connection between Ice-sheet Loss and Global Warming, Researchers Say

The ice-sheets in Greenland and Antarctica are losing about 300 billion tons of ice a year. However, even after years of observation researchers aren't sure if this rate of melting will continue in the future or whether there is a natural system at work.

The satellites of the Gravity Recovery and Climate Experiment (GRACE) have detected minute changes in the ice cover at Greenland and Antarctic since 2002. Researchers say this kind of observation needs to run a little longer to completely understand the cause behind the melting ice in the region.

"In the course of the mission, it has become apparent that ice sheets are losing substantial amounts of ice - about 300 billion tonnes each year - and that the rate at which these losses occurs is increasing.  Compared to the first few years of the GRACE mission, the ice sheets' contribution to sea level rise has almost doubled in recent years," Dr Bert Wouters, currently a visiting researcher at the University of Colorado, according to a press release.

Previous research has shown that human activities have led to an increase in greenhouse gases that accelerate global warming, including the increasing rate of melting of ice sheets. However, shifting pressure systems in North Atlantic- the El Niño and La Niña events- along with slow changes in the oceans can also accelerate the rate of ice sheets' melting.

These ice sheets hold about 99.5 percent of all the glacier ice in the world and if they were to melt completely, the sea-level would rise by 63 meters ( over 206 feet), according to a news release. Researchers aren't sure how the ice-sheets would behave in the future. One way of predicting changes in the ice sheets is to collect data on current melting pattern and extrapolate the findings to estimate the melting rate in the future.

The latest study suggests that there is enough data to analyze the changes taking place in Antarctic ice-sheet, but not of the ice- sheets in Greenland. Using current data to estimate sea-level rise in 2100 could give an error in the estimates, researchers said.

The study is published in the journal Nature Geoscience.                                         

Recently, an iceberg measuring 278 square miles (720 square kilometers), a size that's larger than the city of Chicago, broke off from Antarctica's Pine Island Glacier. Although the scientists who discovered the iceberg didn't draw connections between the split and global warming, many other researchers believe that rising temperatures and thinning of the Antarctic ice-sheet may be the reason behind the event.