Jan 12, 2017

How rapid Arctic sea ice melt may alter global weather patterns

Arctic
by
Michael Kuhne
,
AccuWeather

Significant melting of Arctic sea ice is linked to changing global weather patterns, but climate scientists still have a lot of unanswered questions.

"The Arctic is changing fairly rapidly," NOAA’s Pacific Marine Environmental Lab oceanographer Dr. James Overland said, citing the record low ice extent in November 2016.

In addition to setting a record low in November, Arctic sea ice extent averaged around 4.67-square miles for December 2016, ranking second for the lowest extent in the satellite data record dating back to 1979, according to research published by the National Snow and Ice Data Center (NSIDC). 

One of the ways Arctic sea ice melt may be impacting weather patterns is due to the reduced temperature difference between the Arctic region and the mid-latitudes, which could favor the weakening of the polar jet stream, AccuWeather Meteorologist Brett Anderson said.

Acting as a highway in which storm systems travel along, the jet stream is a fast river of air high in the atmosphere that marks the boundary between cool air to the north and warm air to the south.

"When the polar jet stream weakens it can increase the chances of a 'blocking' pattern over the far north," Anderson added. "These blocking patterns can end up forcing the jet stream to buckle, allowing Arctic air to push much farther south than normal."

The blocking patterns can also favor the development of unusually strong, slow-moving storms in the mid-latitudes, which lead to extremes in weather such as blizzards, floods and major wind events, Anderson said.

Overland said this impact on the eastern United States was noticeable in December 2016, but other factors such as warmth gripping Alaska and the eastern Pacific can also cause variations in eastern North America.

...

With increased ice melt, the Arctic also opens up a dark ocean surface, allowing for the absorption of more sunlight. In turn, this causes more of a warming effect, which makes it an entirely different system than the large, thick ice sheet of the continental Antarctic, Serreze said.

Serreze said many extreme precipitation events can also be attributed to more atmospheric water vapor, but the overall impacts in global weather resulting from a warming Arctic is unknown.

...

Other factors like rising air temperatures, sea surface temperatures and the influence of the tropics in addition to Arctic ice melt all play a role in weather patterns.

Two other major influences on weather are patterns like El Niño and the North Atlantic Oscillation. According to Overland, by studying all of these factors working in tandem with a warming Arctic, its influence may be clearer.