We’ve written extensively about how how arctic ice loss is driving extreme weather. We’ve known for a long time that global warming melts highly reflective white ice and snow, which is replaced by the dark blue sea or dark land, both of which absorb far more sunlight and hence far more solar energy.
That is one of the many sources of “polar amplification,” whereby the Arctic warms much faster than other parts of the globe. Now it seems increasingly clear that the amplified Arctic warming in turn amplifies extreme weather by weakening the jetstream (see video here).
The National Oceanic and Atmospheric Administration (NOAA) explained in an October 2012 news release:
The effects of Arctic amplification will increase as more summer ice retreats over coming decades. Enhanced warming of the Arctic affects the jet stream by slowing its west-to-east winds and by promoting larger north-south meanders in the flow. Predicting those meanders and where the weather associated with them will be located in any given year, however, remains a challenge.
The researchers say that with more solar energy going into the Arctic Ocean because of lost ice, there is reason to expect more extreme weather events, such as heavy snowfall, heat waves, and flooding in North America and Europe but these will vary in location, intensity, and timescales.
Dr. Jennifer A. Francis of Rutgers University’s Institute of Marine and Coastal Sciences explains, “As the Arctic warms at twice the global rate, we expect an increased probability of extreme weather events across the temperate latitudes of the northern hemisphere, where billions of people live.”
This effect is all but certain to become even larger in the next decade or two (see Experts Warn ‘Near Ice-Free Arctic In Summer’ In A Decade If Volume Trends Continue). So all of us need to understand the jetstream better
John Mason at Skeptical Science has put together an extensive, must-read primer, “A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming.” This figure-filled piece also explains key terms we’ll all be hearing more about in the coming years, including the “North Atlantic Oscillation” and “blocking ridge.”
He concludes, “Evidence is mounting to indicate that the response of the jet stream to” polar amplification “has been to tend to slow down and meander more, with a greater tendency to develop blocking patterns,” which in turn prolong and intensify all sorts of extreme weather events. We are only just beginning to sort out the implications of this for key global concerns, such as food security.