Winter cold extremes linked to high-altitude polar vortex weakeningLeave a Comment
- first study to show that changes in winds high up in the stratosphere substantially contributed to the observed winter cooling trend in northern Eurasia.
- study lends further support that a changing Arctic impacts the weather across large swaths of the Northern Hemisphere population centers.
- changes in the jet stream that drives our weather can lead to more abrupt and surprising disturbances-potentially disastrous extremes- to which society has to adapt…
September 22, 2017 Potsdam Institute for Climate Impact Research read full sciencedaily article here
When the strong winds that circle the Arctic slacken, cold polar air can escape and cause extreme winter chills in parts of the Northern hemisphere. A new study finds that these weak states have become more persistent over the past four decades and can be linked to cold winters in Russia and Europe.
…[This study is the] first to show that changes in winds high up in the stratosphere substantially contributed to the observed winter cooling trend in northern Eurasia. While it is still a subject of research how the Arctic under climate change impacts the rest of the world, this study lends further support that a changing Arctic impacts the weather across large swaths of the Northern Hemisphere population centers….
…Despite global warming, recent winters in the Northeastern US, Europe and especially Asia were anomalously cold — some regions like Western Siberia even show a downward temperature trend in winter. In stark contrast, the Arctic has been warming rapidly. Paradoxically, both phenomena are likely linked: When sea-ice North of Scandinavia and Russia melts, the uncovered ocean releases more warmth into the atmosphere and this can impact the atmosphere up to about 30 kilometers height in the stratosphere disturbing the polar vortex. Weak states of the high-altitude wind circling the Arctic then favors the occurrence of cold spells in the mid-latitudes.
….”Jet Stream changes can lead to more abrupt and surprising disturbances to which society has to adapt. The uncertainties are quite large, but global warming provides a clear risk given its potential to disturb circulation patterns driving our weather — including potentially disastrous extremes.”
Marlene Kretschmer, Dim Coumou, Laurie Agel, Mathew Barlow, Eli Tziperman, Judah Cohen. More-Persistent Weak Stratospheric Polar Vortex States Linked to Cold Extremes. Bulletin of the American Meteorological Society, 2017; DOI: 10.1175/BAMS-D-16-0259.1