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Sunday, March 2, 2008

Exceptionally Warm Winter Temperatures at Barrow, Alaska, Baseline Observatory

Global Monitoring Division - ESRL-GMD

The NOAA ESRL Barrow, Alaska, Atmospheric Baseline Observatory located on the most northerly habited point of land in the U.S, has been continuously measuring meteorological parameters since 1977. In November of this year, the average temperature at the observatory was +14.3F (+8C) warmer than the monthly norm. From December 1-10, 2007, the average temperature has been +22.2 F (+12.3C) warmer than the long term average for December. These exceptionally warm temperatures are likely due to heat from the warmer Arctic Ocean off shore from Barrow that is still not frozen for this winter. The Barrow Observatory chief, Dan Endres, who has been at the Barrow observatory for 23 years, notes that in the 1980s the ocean would generally freeze by the middle of October. In recent years, freeze-up has been occurring progressively later.

Background: The summer Arctic ice pack has been thinning and shrinking to unprecedented levels over the past decade. In the fall of this year, the edge of the Arctic ice pack was a record 300 miles (480 km) north of Barrow. The majority of the heat input to the Arctic during the winter is from the open ocean, which is slightly cooler than +32F (0C). The longer the ocean stays open, the more time there is for additional heat to be released into the Arctic atmosphere. The reduced ice pack and increased Arctic temperatures are thought to be related to atmospheric warming from the effects of increasing global greenhouse gas concentrations. However, changes in Arctic Ocean water circulation bringing warmer, lower latitude water to the Arctic, cannot be ruled out.

Significance: These recent changes in extent and thickness of the Arctic ice pack and the warming of the Arctic atmosphere are affecting seal and polar bear habitat, and whale migration patterns. Ship transport operators may soon use this longer open ocean as a sea-lane to transit the Northwest Passage through the Arctic Basin. In response to this probable occurrence, the U.S. Coast Guard is planning on opening a coast guard base at Barrow. The Canadian government has recently announced Canada will open a deepwater Arctic port for stationing Coast Guard and larger ships at the eastern end of the Northwest Passage.

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