Over the past twenty years, glaciers in northern Canada and on Spitsbergen have lost a total of 44 billion metric tons of ice a year. To date, the melting in these regions has been influenced by powerful westerly winds. A team of international researchers, led by the Alfred Wegener Institute, has now determined that both regions are characterised by increased, alternating inflows of cold air from the north and warm air from the south. Due to the ongoing global warming, these fluctuating air currents could also have long-term consequences for the weather in Central Europe.
For the study just released in the journal Nature Climate Change, researchers led by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) calculated ice losses in the glaciers of northern Canada and Spitsbergen from 2002 to 2021, arriving at a combined annual ice loss of ca. 44 billion metric tons. That’s roughly the equivalent of one fifth the mass loss seen in Greenland during the same period. From 2005 to 2017, all glaciers worldwide contributed roughly once centimetre to global sea-level rise.
The team’s calculations draw on analyses of satellite-based observations from the NASA and GFZ mission GRACE-FO, and on modelling data. Said data was then compared with simulations generated by regional climate models specifically designed to portray snowfall and melting in connection with glaciers. In this regard, the experts also determined that, although the glacial ice in northern Canada and on Spitsbergen is continually melting, it is not doing so uniformly: “Since 2003, in 15 out of 17 years, intensive ice loss on Spitsbergen has meant less pronounced ice loss in northern Canada, and vice versa. In the reconstruction using model data up to 1948, this phenomenon is unique in terms of its frequency,” says Ingo Sasgen, an AWI glaciologist and the study’s lead author.
In these regions, the ice mass balance for a given year is predominantly shaped by the melting-related losses in the summer months. The team of researchers determined that, before the year 2000, powerful westerlies influenced both regions equally, but that they have since weakened. As a result, cold air from the Arctic and warm air from the southern latitudes are growing in influence. “Today, the influx of warm air from the middle latitudes is critical to summer melting,” explains Annette Salles, a researcher at the University of Belfast and a co-author of the study. “Depending on the year, these patterns produce more melting either in northern Canada or on Spitsbergen.”
The reasons for this change in atmospheric circulation are the subject of intensive research efforts. “There are a number of possible suspects, but we’re far from having solved the puzzle. What we do know is that the dramatic loss of sea ice and decreased snow cover over the last several decades have made the Arctic latitudes substantially warmer,” says Martin Wegmann, a study co-author from the University of Bern. As a result, the Arctic is now warming at more than twice the speed of the global average. “This extreme warming is reducing the temperature difference between the Arctic and middle latitudes, which can influence macro-scale circulation and high-altitude winds.” This will likely also have consequences for the weather in Central Europe.
Original publication:
Ingo Sasgen, Annette Salles, Martin Wegmann, Bert Wouters, Xavier Fettweis, Brice P. Y. Noel and Christoph Beck: Arctic glaciers record wavier circumpolar winds. Nature Climate Change, 10.02.2022, DOI: 10.1038/s41558-021-01275-4