Photo by Paulo Brando.
From more severe winters to drier summers, weather patterns seem to have become increasingly “stuck” lately. Prolonged cold, rain, heat, or clear skies are increasingly obvious. The changing climate and rapidly warming Arctic are likely interfering with the jet stream, the creator of most weather systems in temperate latitudes across the planet. The complex pieces of this puzzle are the focus of Dr. Jennifer Francis’ research — in particular, the factors contributing to the nearly three-fold increase in the frequency of extreme weather events since the 1980s.
The Arctic has experienced a dramatic loss of sea ice and spring snow cover, a direct consequence of additional heat-trapping gasses in the atmosphere caused mainly by burning fossil fuels. This loss of bright, white surfaces sets off vicious cycles—or positive feedback loops—that amplify global warming and cause high northern latitudes to warm about three times faster than the globe as a whole. Rapid Arctic warming has decisively altered the speed and shape of the jet stream and with it, the behavior of weather patterns on local and hemispheric scales.
The schematics above illustrate jet streams that are strong and straight (left) versus weaker and wavier (right). (Credit: Financial Times)
While it is difficult to blame climate change or the warming Arctic for causing any particular weather event, the recent spate of heatwaves, cold spells, floods, and droughts is just what scientists have expected to occur as humans augment greenhouse gas concentrations. But the mechanisms connecting climate change with weather events are complex and difficult to pin down. Further research may find ways to predict who will experience which extreme conditions in a particular season, but in the meantime, it is increasingly likely that current weather patterns will stick around longer, leading to more frequent, destructive, and expensive extreme events.