Study says iceberg calving only a minor factor
By Summit Voice
FRISCO — As the Antarctic ice sheet loses volume, researchers are racing to understand how those sheets interact with the rest of the climate system and why the ice is melting. The answers to those questions are important because every bit of ice that melts contributes to global sea level rise, and research is increasingly showing that melting at the bottom of submerged ice shelves is the single biggest factor, accounting for as much as 90 per cent of ice loss in some areas.
For many decades, experts believed that the most important process responsible for this huge loss was iceberg calving — the breaking off of chunks of ice at the edge of a glacier. But a new study led by scientists From the University of Bristol with colleagues at Utrecht University and the University of California, used satellite and climate model data to prove that this sub-shelf melting has as large an impact as iceberg calving for Antarctica as a whole and for some areas is far more important.
The study, published September in Nature, suggest that ice shelves which are thinning already were identified as losing most of their mass from this melting, a finding which will be a good indicator for which ice shelves may be particularly vulnerable to changes in ocean warming in the future.
The scientists used data from a suite of satellite and airborne missions to accurately measure the flow of the ice, its elevation and its thickness. These observations were combined with the output of a climate model for snowfall over the ice sheet.
They compared how much snow was falling on the surface and accumulating against how much ice was leaving the continent, entering the ocean and calving. By comparing these estimates, they were able to determine the proportion that was lost by each process.
“Understanding how the largest ice mass on the planet loses ice to the oceans is one of the most fundamental things we need to know for Antarctica. Until recently, we assumed that most of the ice was lost through icebergs,” said Professor Jonathan Bamber, from the University of Bristol’s School of Geographical Sciences. “Now we realize that melting underneath the ice shelves by the ocean is equally important and for some places, far more important. This knowledge is crucial for understanding how the ice sheets interact now, and in the future, to changes in climate.”