OSLO May 6 The Arctic ecosystem, already under
pressure from record ice melts, faces another potential threat
in the form of rapid acidification of the ocean, according to an
international study published on Monday.
Acidification, blamed on the transformation of rising levels
of the greenhouse gas carbon dioxide from the air into carbonic
acid in the sea, makes it harder for shellfish and crabs to grow
their shells, and might also impair fish reproduction, it said.
Cold water absorbs carbon dioxide more readily than warm
water, making the Arctic especially vulnerable. The report said
the average acidity of surface ocean waters worldwide was now
about 30 percent higher than at the start of the Industrial
"Arctic marine waters are experiencing widespread and rapid
ocean acidification," said the report by 60 experts for the
Arctic Monitoring and Assessment Programme, commissioned by the
eight nations with Arctic territories.
"Ocean acidification is likely to affect the abundance,
productivity and distribution of marine species, but the
magnitude and direction of change are uncertain."
At almost 400 parts per million (ppm), there is now 40
percent more carbon dioxide in the atmosphere than before the
industrial era began. Almost all experts say the rise is linked
to the burning of fossil fuels.
With global surface temperatures rising, the Arctic sea ice
shrank in 2012 to the smallest area since satellite records
began, disrupting the hunting livelihoods of indigenous peoples
and opening the region to more shipping and oil and gas
exploration. As yet, the consequences of acidification are
harder to predict.
Experiments with the eggs of brittlestars, which are related
to starfish, showed that they died within days when exposed to
the levels of acidification likely in coming decades, said Sam
Dupont, one of the report's authors from the University of
Gothenburg in Sweden.
That would have knock-on effects on creatures that prey on
them, such as crabs and fish.
The report said adult and juvenile fish were likely to cope
with levels of acidification likely in the coming century but
fish eggs and young larvae might be more sensitive.
In general, the report said, fish stocks might be more
"robust to ocean acidification" if the other stresses they are
already subject to, such as overfishing or habitat degradation,
A warming of Arctic waters means that plankton are growing
further north, providing a new source of food for fish such as
cod and salmon, but Dupont said acidification would "constrain
the positive effects of warming" for some species.
Meanwhile some types of seagrass seem likely to thrive with
Overall, Dupont said, acidification was "an additional
stressor on a system that is already quite fragile".
The report will be presented to Arctic governments at a
meeting in Sweden next week attended by U.S. Secretary of State
John Kerry and Russian Foreign Minister Sergei Lavrov, among
(Editing by Kevin Liffey)