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A new study of Utrecht ľ¹Ï¸£ÀûÓ°ÊÓ climate scientists shows that no part of the vast Antarctic ice sheet is safe from the heating ocean. The results were published in the renowned journal Nature on 15 September.

The vast ice sheet of Antarctica covers almost the entire continent, is two kilometres thick on average and contains enough water to cause a worldwide sea level rise of almost sixty metres. The movement of the ice starts inland and proceeds to the edges of the continent, where it culminates into ice shelves with a thickness of hundreds of metres, which results in the famous Arctic table icebergs at the outer edges. Some ice shelves can become as large as the country of France.

Deep below

Because of the thickness of the ice shelves, not much is known about the processes that take place at the bottom. "In our research, we calculated that between the moment the ice leaves the continent and the iceberg breaks off at the front, the ocean waters have already melted half of the ice at the bottom of the ice shelf", explains Michiel van den Broeke, Professor of Polar Meteorology at Utrecht ľ¹Ï¸£ÀûÓ°ÊÓ. Van den Broeke and his Utrecht ľ¹Ï¸£ÀûÓ°ÊÓ colleagues Jan Lenaerts and Stefan Ligtenberg as well as researchers from the ľ¹Ï¸£ÀûÓ°ÊÓ of Bristol are the authors of the study. Van den Broeke: "This means that the thickness of these ice shelves is very sensitive to minor changes in the oceanic temperature."

Natural obstacle

The study also shows that there the melting rate varies substantially from location to location. In particular ice shelves that are rapidly melting at the bottom - ten metres or more per year - have thinned at an alarming rate in recent decades. Since the ice shelves already float in the ocean, their melting does not contribute to the sea level rise. However, because the ice shelves actually start to act as a type of natural obstacle for the inland glaciers, the glaciers will start to flow more quickly the moment the ice sheets become thinner, which results in a sea level rise. This process has been going on for years in West Antarctica and appears to have also started in some parts of East Antarctica. "It seems that no part of the Antarctic ice sheet is safe from the heating ocean", says Van den Broeke.

More information

• Prof. Michiel van den Broeke, Faculty of Science, IMAU, M.R.vandenBroeke@uu.nl, +31 (0)6 12 938 460
• For other questions: Tom de Kievith, Press Officer of the Faculty of Science, T.deKievith@uu.nl, +31 (0)6 13 661 438
• The publication 'Calving fluxes and melt rates of Antarctic ice shelves’ on the website of Nature