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Alaskan Cold and Glacial Advance Due to PDO

Written by Joseph D'Aleo

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November 28, 2008
By Joseph D'Aleo, CCM, Fellow AMS
IceCap.us

The PDO not Greenhouse Gases are responsible for changes in Alaska

The PDO has a major influence on Alaskan and for that matter global temperatures. The positive phase favors more El Ninos and a stronger Aleutian low and warm water in the north Pacific off the Alaskan coast. The negative phase more La Ninas and cold eastern Gulf of Alaska waters. The combination of a stronger Aleutian low and warm water off the coast leads to warmer temperatures in Alaska in the +PDO phase and a weakened Aleutian low, colder water, colder temperatures in the negative phase.

The PDO flip in 1977 from negative (which correlated with more frequent La Ninas) to positive (with more frequent El Ninos). More frequent La Ninas and weaker El Ninos followed the recent decline. In Alaska, the sudden Great Pacific Climate Shift (from negative to positive PDO) in 1977 led to a step-ladder warming.

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We will update this after the annual 2008 temperatures become available in January. See larger image here.

The decline since 1999 and especially since 2007 has led to rapid cooling and heavy snows. Alyeska, Alaska picked up 826� (nearly 70 feet) of snow last snow season. This was followed by an extremely cold summer and a sudden advance of Alaskan Glaciers for the first time in 250 years.

Anchorage reached 65F only 16 times this past summer, tying the record set in 1970 for least 65F days. It broke the record for least 70F days with only 2.

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See larger image here

With heavy winter snows and a cold spring and summer, the ice did not melt as much as usual - the result was a net annual advance in Alaskan glaciers.
As Michael Asher reported October 16, 2008 in Daily Tech, Alaskan Glaciers Grow for First Time in 250 years: A bitterly cold Alaskan summer has had surprising results. For the first time in the area's recorded history, area glaciers have begun to expand, rather than shrink. Summer temperatures, which were some 3 degrees below average, allowed record levels of winter snow to remain much longer, leading to the increase in glacial mass.

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And the cold continued this fall. This is part of a statement from the National Weather Service in Fairbanks on November 24th.

...A COLD START TO WINTER THIS YEAR AT FAIRBANKS...
October ended up as the 4th coldest in the last 104 years of weather record at Fairbanks. The total of 13 days with a low temperature below zero was the most since 1965. November has also been much colder than average. Through yesterday ...the average temperatures of -2.3 degrees was 7.3 degrees below the 30-year average. It has been the 8th coldest November in the last 50 years. There have been a total of 20 days So far this month where the temperature has fallen below zero...which is already above the average of 18 days for the entire month.  Read more here.
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