International Polar Year 2007–2008 - WMO

temperature, it is now apparent from historical records
(Sundby and Nakken, 2005) that the Arcto-Norwegian
cod stock has made subtle adjustments to temperature
in terms of its spawning location: a clear relative shift
into the two northernmost spawning districts (Troms
and Finnmark) and out of the southernmost district
(Møre) during the earlier and recent warm episodes;
and with a reverse southward shift during the cool
periods prior to the 1930s, and in the 1960s and 1970s
(Fig. 2.2-9). The recovery of the East Finnmark spawning
areas after a 40-year absence (arrowed in Fig. 2.2-9) is,
therefore, the expected response to the most recent
waves of warming along the Norway coast. Other noncommercial
fish species appear to have participated
in the same poleward shift in distribution, one of the
more conspicuous being the snake pipefish, which has
rapidly spread from the North Sea to the Svalbard shelf
and Barents Sea since 2003 (Harris et al., 2007).
Projected effects of climate change on the
environment and ecosystem of the Barents Sea. The
Barents Sea is not only an important high latitude
nursery and feeding area for commercial fish stocks
such as cod, capelin and herring; its ecosystem is
divided by the presence of the Ocean Polar Front (OPF)
into cold-Arctic and warm-Atlantic ecotypes making
it potentially liable to a large space-time variability. Its
‘environment: ecosystem’ relations provide a valuable
test of skill and a source of management advice in
simulating the effects of climate change. Ellingsen et
al., (2008) have conducted such a study, providing a
modern account of the expected changes. Combining
a hydrodynamic model (SINMOD) with an ecosystem
model (Wassman et al., 2006), they compare a baseline
scenario (1990-2004) based on realistic forcing and
observational data with a 65-year climate change run
(1995-2059) using atmospheric input from a hydrostatic
regional climate model REMO that has been run for the
ECHAM4/OPYC3 IPCC-SRES B2 scenario by the Max-
Planck-Institut for Meteorology, Hamburg. Their main
conclusions are first, that there will be no change in
the decade-mean inflow to the Barents Sea over the
next 50 years. Nevertheless, the temperature of the
inflow will become substantially higher (increase of 1°C
during the simulation period) so that the temperature
of the Barents Sea will increase, the fraction of water in
the Barents Sea warmer than 1°C will increase by 25%
and the fraction occupied by the Arctic watermass will
decrease. Second, the position of the Ocean Polar Front
will move toward the north and east. Third, primary
production in the Barents Sea will increase during the
next 50 years, primarily in the eastern and northeastern
Barents Sea (Fig. 2.2-10). Fourth and final, the
zooplankton biomass of Atlantic species will increase
by 20% in the eastern Barents Sea, but this will not be
enough to offset the 50% decrease in the abundance
of Arctic zooplankton species that will accompany the
Fig. 2.2-9. Relative
north-south shifts
in the spawning
location of the
Arcto-Norwegian
cod stock over past
century in response
to long-term changes
in ocean temperature.
Based on a roe index
defined by Sundby
and Nakken (2005),
panels (a) and (b)
show the relative shift
in spawning activity
from More in the
south (red bars) to the
Troms and Finmark
spawning areas in
the north (blue bars)
during the warmer
middle decades of
the past century. The
arrow to the right of
panel (b) indicates
the recovery of East
Finmark spawning
areas during the
most recent wave of
warming in 2004 and
2005 after 40 years
of absence, while
panel (c) shows the
long-term changes
in Barents Sea
temperature along
the Kola Section at
33°30’E.
s C I e n C e P r o g r a m 171