The Davis Strait - DCE - Nationalt Center for Miljø og Energi

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8 Impacts of climate change
Doris Schiedek, Morten Frederiksen, Michael Dünweber, (AU) & Martin Blicher
(GINR)
8.1 General context
One of the main findings of the AMAP assessment concerning the impacts of
climate change on Snow, Water, Ice and Permafrost in the Arctic (SWIPA)
has been that the period 2005-2010 was the warmest ever recorded in the
Arctic environment (AMAP 2011). Since 1980 the increase in annual average
temperature has been twice as high in the Arctic region as in other parts of
the world. Changes in weather patterns and ocean currents have been observed,
including higher inflows of warm water entering the Arctic Ocean
from the Pacific.
Average autumn-winter temperatures are projected to increase by 3 to 6°C
by 2080, even when using scenarios with lower greenhouse gas emissions
than those recorded in the past ten years. It has also been predicted that sea
ice thickness and summer sea ice extent will continue to decline, though
with considerable variation from year to year. A nearly ice-free summer is
now considered likely for the Arctic Ocean by the middle of the century
(AMAP 2011).
Also in Greenland, 2010, for example, was marked by record high air temperatures,
ice loss through melting, and marine-terminating glacier area loss.
Summer seasonal average (June-August) air temperatures around Greenland
were 0.6 to 2.4°C above the 1971-2000 baseline and were highest in the
west. A combination of a warm and dry 2009-2010 winter and the very
warm summer resulted in the highest melt rate since at least 1958, and an
area and duration of ice sheet melting that was above that in any previous
year on record since at least 1978. There is now clear evidence that the ice area
loss rate of the past decade (on average 120 km 2 /year) is greater than it
was before 2000 (Box et al. 2010).
Ongoing and future warming has an impact on marine ecosystems in Greenland
in many ways. An increase in water temperature has a direct influence
on organisms and their metabolism, growth and reproduction. Depending
on the acclimation capacity of local species, changes in distribution patterns
and species diversity are to be expected, with severe consequences for the
composition of biological communities and their productivity and influencing
in turn ecosystems on local and regional scales.
Changes in oceanographic conditions will affect primary production and
thereby the timing, location and species composition of phytoplankton
blooms. This will in turn affect zooplankton communities and the productivity
of fish; e.g. a mismatch in timing of phytoplankton and zooplankton production
due to early phytoplankton blooms may reduce the efficiency of the
food web. Food web effects could also occur through changes in the abundance
of top-level predators, but the effects of such changes are more difficult
to predict. Generalist predators are likely to be more adaptable to
changed conditions than specialist predators. All in all, significant alterations
are to be expected for the entire food web.