Sea ice melts away in the Antarctic summer before starting to grow again as autumn arrives. “In past years, the annual minimum has occurred between 18 February and 3 March, so further decline is expected,” the NSIDC researchers said. “Much of the Antarctic coast is ice free. Earlier studies have linked low sea ice cover with wave-induced stresses on the floating ice shelves that hem the continent, leading to break up of weaker areas.”
The German scientists said the “intense melting” could be due to unusually high air temperatures to the west and east of the Antarctic peninsula, which were about 1.5C above the long-term average. Furthermore, there have been strong westerly winds, which increase sea ice retreat. The result is “intensified melting of ice shelves, an essential aspect of future global sea-level rise”, the researchers said.
Historical records also show dramatic changes in Antarctica, they said. The Belgian research vessel Belgica was trapped in massive pack ice for more than a year in the Antarctic summer 125 years ago, in exactly the same region where the Polarstern vessel is now sailing in completely ice-free waters.