[Vision2020] Warm Arctic, Cold Continents: NOAA scientists may have a clue

[Ted Moffett]

 http://www.monbiot.com/2009/11/23/the-knights-carbonic/
"Our co-option of the physical world has been just as successful. The
thinning of the Arctic ice cap was a masterstroke. The ring of secret
nuclear power stations around the Arctic Circle, attached to giant
immersion heaters, remains undetected, as do the space-based lasers
dissolving the world’s glaciers."
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Warm Arctic, Cold Continents
Changes in the Arctic Are Hitting Closer to Home

http://www.noaa.gov/features/02_monitoring/warmarctic.html

It’s a puzzle: How could warmth in the Arctic produce frigid
conditions elsewhere?

NOAA scientists may have a clue.

Extremely cold winds have swept down through the Northern Hemisphere
recently, reaching as far south as the state of Florida and causing
record low temperatures in January. The unusually cold winter of
2009–2010 – which saw massive snowstorms dubbed “Snowpocalypse” and
“Snowmageddon” — and the frigid start to 2011 in the eastern United
States and Europe have scientists talking about what might be
influencing the weather.

Dr. James Overland, a scientist at NOAA’s Pacific Marine Environmental
Laboratory (PMEL) in Seattle, has been studying the changing
conditions in the Arctic for 30 years. He explains why the
deterioration of the Polar Vortex could be leading to some of these
extreme winter weather events.

“When the Polar Vortex — a ring of winds circling the Arctic — breaks
down, this allows cold air to spill south, affecting the eastern
United States and other regions,” says Dr. Overland. “This can result
in a warmer-than-average Arctic region and colder temperatures that
may include severe winter weather events on the North American and
European continents.”

A Polar Vortex link to Winter 2009-2010?

The Polar Vortex is a strong wind flowing around a low-pressure system
normally present over the Arctic in winter. Average December values
from 1968–1996 show the Polar Vortex remaining strong and helping to
keep the cold air in the Arctic region. During winter of 2009–2010,
this normal pattern broke down, and a weakened Polar Vortex allowed
cold Arctic air to move southward.

“In December 2009, the Arctic was 9 degrees F warmer than normal, and
mid-latitude continents were 9 degrees F cooler than normal, with
record cold and snow conditions in northern Europe, eastern Asia and
eastern North America,” says Dr. Overland. “This is the Warm
Arctic-Cold Continents pattern. The winter of 2009–2010 had especially
extreme weather in the U.S. as moisture from El Nino hit cold air from
the Arctic.”

Why are we seeing these changes now?

According to the 2010 Arctic Report Card, there is reduced sea summer
sea ice cover, record snow cover decreases, and record temperatures.
Could these changes be linked to the weakened Polar Vortex and extreme
winter weather events?

Many factors, including natural climate variability, can produce
extreme weather events. But, there also is a potential impact from
Arctic regions, where solar heat absorbed by recently ice-free regions
of the ocean warms the atmosphere during autumn, impacting the winds.
More research is needed to study the causes and extent of the recently
observed Warm Arctic-Cold Continent pattern.

“Some scientists are beginning to suspect that the lack of sea ice
allows the oceans to pump heat into the atmosphere in the Arctic in a
way that could impact weather patterns such as the North Atlantic
Oscillation,” said Mark Serreze, director of the National Snow and Ice
Data Center. “The idea is still very much in its infancy, but it’s
worth looking into. If it turns out to be right, it could help to
explain the frigid winters the eastern United States and Europe have
experienced these past two years.”

The North Atlantic Oscillation (NAO) is a natural climate pattern that
is the dominant mode of winter climate variability for the region,
which ranges from central North America to Europe and into Northern
Asia. A strongly negative NAO can indicate a breakdown of the Polar
Vortex. Last winter, there were two extreme cold continent events —
and the breakdown of the Vortex, as measured by the NAO, was the most
extreme on record for the past 145 years.

Undoubtedly, changes in the Arctic are being felt near and far. The
winters of 2009 and 2010 serve as a jumping off point for more
research to determine potential linkages between Arctic changes and
continental weather to help predict if the Northern latitudes will
witness colder winters in the future as more summer sea ice is lost.

Learn more about NOAA’s “cool” work in the Arctic: Visit www.arctic.noaa.gov.

Posted Feb. 28, 2011
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Vision2020 Post: Ted Moffett