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State of the Arctic Report
Executive
Summary
This State of the Arctic Report
presents a review of recent data by an international group of scientists who
developed a consensus on the information content and reliability. The report
highlights data primarily from 2000 to 2005 with a first look at winter 2006,
providing an update to some of the records of physical processes discussed in
the Arctic Climate Impact Assessment (ACIA, 2004, 2005).
The Arctic system generally shows
signs of continued warming, as illustrated in this northern hemisphere map of
springtime (MarchApril May, or MAM) surface air temperature anomalies for
20002005 that differ from earlier temperature patterns in the 20th century.
Yellow and red indicate temperatures at least 1.C above average relative to a
19681996 base period.
Of particular note:
Atmospheric climate
patterns are shifting . The late winter/spring pattern for 20002005 had new
hot spots in northeast Canada and the East Siberian Sea relative to 19801999.
Late winter 2006, however, shows a return to earlier climate patterns, with
warm temperatures in the extended region near Svalbard.Ocean salinity and
temperature profiles at the North Pole and in the Beaufort Sea, which changed
abruptly in the 1990s, show that conditions since 2000 have relaxed toward the
pre-1990 climatology, although 20012004 has seen an increase in northward
ocean heat transport through Bering Strait , which is thought to impact sea
ice loss.
Sea ice extent
continues to decrease. The sea ice extent in September 2005 was the minimum
observed in summer during the satellite era (beginning in 1979), marking an
unprecedented series of extreme ice extent minima beginning in 2002 . The sea
ice extent in March 2006 was also the minimum observed in winter during the
satellite era.
Tundra vegetation greenness
increased, primarily due to an increase in the abundance of shrubs. Boreal
forest vegetation greenness decreased, possibly due to drought
conditions
. There is increasing
interest in the stability of the Greenland ice sheet. The velocity of outlet
glaciers increased in 2005 relative to 2000 and 1995, but uncertainty remains
with regard to the total mass balance.
Permafrost temperatures
continue to increase. However, data on changes in the active layer thickness
(the relatively thin layer of ground between the surface and permafrost that
undergoes seasonal freezing and thawing) are less conclusive. While some of
the sites show a barely noticeable increasing trend in the thickness of the
active layer, most of them do not. Globally, 2005 was the warmest year in
the instrumental record (beginning in 1880), with the Arctic providing a large
contribution toward this increase.
Loss of sea ice and warmer ocean
temperatures, highlighted in this report, have favored the pollock fishery in
Alaskan waters. (Bryan & Cherry Alexander Photography.)
Many of the trends documented in
the ACIA are continuing, but some are not. Taken collectively, the observations
presented in this report indicate that during 20002005 the Arctic system
showed signs of continued warming. However, there are a few indications that
certain elements may be recovering and returning to recent climatological norms
(for example, the central Arctic Ocean and some wind patterns). These mixed
tendencies further illustrate the sensitivity and complexity of the Arctic
physical system. They underline the importance of maintaining and expanding
efforts to observe and better understand this important component of the climate
system to provide accurate predictions of its future state.
NOAA
State of the Arctic Report
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