Examining the Influence of Greenland Ice Sheet Melting and Atlantic Meridional Shutdown on the Climate of Scandinavia and the British Isles

Earth’s climate has been rapidly changing over the last hundred years, and its global average temperature is rising. However, climate change is far more complicated than a simple increase in temperature. For example, it is theorized that certain regions of Earth, including Scandinavia and Northern Europe, could actually become cooler through ongoing climate change processes. Two of these processes are Greenland Ice Sheet (GrIS) melting, and slowdown of the Atlantic Meridional Overturning Circulation (AMOC). This research examines if climate change, through GrIS melting and AMOC slowdown, could contribute to cooler, instead of warmer, temperatures in Scandinavia and Northern Europe.

The Weather Research and Forecasting regional climate model (WRF) was used to emulate a slowdown of AMOC via a widespread 5 degree Celsius sea surface temperature decrease near the southern coast of Greenland. Although WRF contains a simple three-dimensional ocean model, this module was added relatively recently and was not used for this work. An experiment was run for a 1979-2009 time period over a domain covering Greenland, the British Isles and Scandinavia, forced by the NCEP Climate Forecast System (CFS). Two runs were performed: a control run, and an adjusted run including the sea surface temperature anomaly. The resulting climatology included a cooling of surface temperature in Scandinavia and Northern Europe of roughly half a degree Celsius for the adjusted run, with a larger anomaly present in winter months. Other features of the adjusted run included a lower tropopause for the region, drier air in Scotland and Scandinavia, and varying regional positive and negative anomalies of total precipitation and snow and ice, all again slightly more intense during colder months. It is surmised that a slowdown of AMOC, leading to cooler sea surface temperatures in the North Atlantic, would lead to generally cooler and drier conditions for Northern Europe.