4
WATER-COLUMN STRATIFICATION AND
6
OCEAN
LOSS OF COASTAL PUMPS ACIDIFICATION
Warming and melting is enhancing seasonal water-column strati- The ocean is absorbing excess CO
2
from the atmo-
fication in the ocean on a global scale, mainly in temperate seas. sphere which is causing changes in the biogeochemi-
Some coastal ”flushing” mechanisms – so-called dense-shelf water cal carbonate balance of the ocean, and thus signifi-
cascading – may also be weakened with climate change, resulting cant acidification of ocean waters. The ocean is thus
in slower “cleaning” of polluted coastal waters, more algae blooms somehow alleviating the impacts of global warming
and dead zones, and lack of transport of food particles to organisms in the biosphere. With climate change and ocean acid-
living in the deep sea and on the sea floor. The resulting reduction ification a large reduction in the ability of the ocean
in nutrient flux will cause a decline in primary production and pos- to take up atmospheric CO
2
is expected. The reduc-
sibly in ocean productivity. tion of pH and calcium carbonate saturation levels in
the oceans will affect thousands of species from the
wide range of marine organisms which need carbon-
5
SHIFTS IN DISTRIBUTION OF SPECIES ate in their development and for forming shells and
AND MIGRATORY ROUTES skeletons. The structure of marine ecosystems are ex-
The distribution of plankton, fish and other marine fauna has shift- pected to be severely impacted by acidification with
ed hundreds of kilometers toward higher latitudes, especially in the potential extinctions and large-scale reduction in bio-
North Atlantic, the Arctic Ocean, and the Southwest Pacific Ocean. diversity and ecosystem services, primarily because
1958 - 1981 1958 - 1981
A
1958 - 1981
dditionally
1982 - 1999
ocean warming
1982 - 1999
has noticeable
1982 - 1999
effects
2000 - 2002
on the migratory
2000 - 2002
of the s
2000 - 2002
peed at which these water chemistry changes
routes of many species. are occuring.
1958 - 1981 1982 - 1999 2000 - 2002
Global ocean acidification
Oceanic CO
2 Ocean water
concentration
acidity
atm pH
380 8.14
360 8.12
1958–1981 1982–1999 2000–2002
340 8.10
Mean number of species per CPR sampleMean number of species per CPR sampleMean number of species per CPR sampleMean number of species per CPR sample
0.0
Source: based on
0.0
0.0
Ahlenius, H., 2008; P
0.1
ersonal
0.0
communication
0.1
0.1
with Chris Reid, SAHFOS, No
0.1
vem-
320 8.08
ber 2007.
Figure 13. Plankton migration shift.
300 8.06
� Figure 14. As carbon concentrations in the atmosphere increase, so
1985 1990 1995 2000 20051985 1990 1995 2000 2005
do concentrations in the ocean, with resultant acidification as a natural
chemical process.
Source: IPCC, 2007.
32
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