Long-range weather predictions are notoriously difficult, but a new paper in the journal Weather and Climate Dynamics suggests that the melt rate of the Greenland ice sheet can predict the next summer’s weather in Europe.
The chain of events is complex and other factors may interfere. But according to Dr Marilena Oltmanns of the UK National Oceanography Centre, lead author of the study, it goes roughly as follows:
Warm conditions in Greenland bring more glacial meltwater into the Atlantic. Being lighter than seawater, this meltwater sits on top of the ocean and reduces the heat exchange between the air and the sea. This leads to stronger winds around the meltwater region. In winter, the winds produce a northward shift in the North Atlantic current, an extension of the Gulf Stream.
The next summer, winds follow the direction of the current and are redirected northward. This helps form the type of large-scale atmospheric circulation conditions that bring warmer and drier weather over Europe.
Oltmanns says the location, extent and strength of freshwater events can be used to estimate the subsequent pattern of warm and dry weather over Europe.
“Based on the identified chain of events, we expect that the ocean-atmosphere conditions will be favourable for an unusually warm and dry summer over southern Europe this year,” says Oltmanns.
