Russia – June 21st, 2013
Visible on the right side of this image is the Novaya Zemlya archipelago, part of Russia, between the Barents and Kara Seas. Recent data over the last decade show an Arctic wide temperature increase consistent with model projections of global warming rather than showing regional warming patterns which would have been caused by natural variability as occurred in previous Arctic warming episodes such as the 1930s.
While a major surprise was the nearly 40% loss of September sea ice extent in 2007, the major change is that in every year since then sea ice has been below 30% and that much old, thick sea ice has disappeared. Extensive forest fires are another major Arctic change. These shifts seem to be rapid and occurring 20-30 years earlier than expected by steady processes in climate forecast models.
The Arctic is normally dominated a very stable “Polar Vortex” of counter-clockwise circulating winds surrounding the North Pole which traps the cold Arctic air mass at high latitudes. However, during early winter of 2009-2010 the Polar Vortex weakened due to higher geopotential heights over the Arctic, allowing cold air to spill southwards and be replaced by warm air moving poleward, a warm Arctic –cold continent climate pattern. One
indicator of a weak Polar Vortex is the North Atlantic Oscillation (NAO) index which in December 2009 through February 2010 had its most negative value (weak vortex) in 145 years of record.
Meteorological attribution to these sub-Arctic events is difficult. Certainly random chaos in the development of weather patterns can produce such extreme events. There is a potential impact, however, from Arctic regions where heat stored in the ocean in sea-ice-free and thin ice areas has been released to the lower atmosphere during autumn. One would not expect a sub-Arctic impact in every year or the in the same locations every year. The Barents Sea seems to be part of the Arctic wide warming pattern, while northern Europe is in the subArctic high climate variability zone (click here for more information).
