Geoscience Reference
In-Depth Information
There has been increased coastal erosion in the Bering Sea from storm surges,
resulting from reduced sea ice.
￿
Sea ice extent in the Arctic has decreased overall by 0.35 % per year since 1979.
During summer of 1998, the record reduction of sea ice coverage was observed
in the Beaufort and Chukchi Seas. Sea ice area is assessed by 11,827,773 km 2
on December 2013.
￿
Sea ice thickness has also been reduced by one to two meters in most parts of
the Arctic Ocean and the sub-Arctic seas. On October 2013, the multiyear ice
had been on average at about 20 %, or around 30 cm, thicker than last year.
￿
Stream
flow discharge of major Siberian Rivers into the Arctic Ocean was
increased in recent years and is associated with a warmer climate and enhanced
precipitation in the river basins.
fl
￿
Since 1970, the Arctic Oscillation, which is a measure of the strength of the
circumpolar vortex, has strengthened. This has been found to be consistent with
temperature change in the Arctic.
￿
￿
There has been a raise in temperatures of the water in the Arctic Ocean
'
s
Atlantic layer and an approximate 20 % greater coverage of Atlantic waters.
￿
Record of low levels of ozone was measured in 2000 in the Arctic, with
increasing evidence that these levels are likely to continue for at least the next
20 years.
Ongoing studies indicate that the current UV levels can have a significant effect
on the
￿
fish larvae survival rates.
General warming of the soils in regions with permafrost, speci
cally from
￿
Alaskan regions, has been observed over recent years.
It has been emphasized in ACIA (2000) that past assessments indicated that the
Arctic is important to global-scale processes in at least four important ways:
The thermohaline circulation dominated by the Arctic Ocean and Nordic Seas is
responsible for a considerable part of the Earth
￿
s pole ward heat transport and
may also serve as a sink for CO 2 . Alterations of this circulation, as have been
observed during climatic changes of the past, can affect global climate and in
particular the climate of Europe and North America.
'
The melting of the Arctic land ice sheets can cause sea level rise around the
world. A compilation of studies suggests that a global warming of 1
￿
°
C will lead
to
1 mm raise per year of the sea-level from small ice caps and glaciers. The
Arctic will supply over half of this total, with an additional 0.3
*
0.4 mm per year
contribution from Greenland, although uncertainties remain about
-
the mass
balance of the Greenland ice sheet.
￿
Arctic soils can act as either sinks or sources of greenhouse gases, depending on
temperature and moisture changes within the Arctic. Moisture has contradictory
effects on the concentrations of the two major trace gases: CH
fl
flux declines with
soil drying while CO 2 fl
flux initially increases. These changes can in
fl
uence
greenhouse gas warming globally.
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