Arctic Pollution

Arctic Ocean May be Polluted Soup by 2070
By Kate Ravilious

WITHIN 60 years the Arctic Ocean could be a stagnant, polluted soup.
Without drastic cuts in greenhouse-gas emissions, the Transpolar Drift, one
of the Arctic’s most powerful currents and a key disperser of pollutants,
is likely to disappear because of global warming.

The Transpolar Drift is a cold surface current that travels right across
the Arctic Ocean from central Siberia to Greenland, and eventually out into
the Atlantic. It was first discovered in 1893 by the Norwegian explorer
Fridtjof Nansen, who tried unsuccessfully to use the current to sail to the
North Pole. Together with the Beaufort Gyre, the Transpolar Drift keeps
Arctic waters well mixed and ensures that pollution never lingers there for
long.

To better understand the dispersal of pollution in the Arctic Ocean, Ola
Johannessen, director of the Nansen Environmental and Remote Sensing Center
in Bergen, Norway, and his colleagues studied the spread of radioactive
substances such as strontium-90 and caesium-137 from (see Russia’s toxic
shocker) nuclear testing, bomb factories and nuclear power-plant accidents.
Measurements taken between 1948 and 1999 were plugged into a
high-resolution ocean circulation model and combined with a climate model
to predict Arctic Ocean circulation until 2080.

Their model confirmed that most pollutants, including pesticide, petroleum
residue and nuclear fallout, are currently washed out into the north
Atlantic by the Transpolar Drift. But perhaps not for much longer. In a
nuclear accident, more radioactive material would be contained in the
Arctic Ocean for much longer.

In a “business-as-usual” scenario, in which atmospheric carbon dioxide
levels double by 2070, Johannessen and his colleagues found that the
Transpolar Drift stops and the Beaufort Gyre, Greenland Current and Gulf
Stream weaken considerably (Journal of Environmental Radioactivity, DOI:
10.1016/j.jenvrad.2009.01.003). One reason for this sluggish behaviour is a
change in wind patterns driven by global warming and rapid melting of the
Arctic sea ice.

As a result, pollution takes much longer to disperse in this scenario. Much
of this pollution would congregate along the non-European coastlines of the
Arctic Ocean, the model suggests.

Jeff Ridley of the Met Office Hadley Centre in Exeter, UK, agrees that
surface circulation in the Arctic Ocean will weaken if sea ice disappears,
but he doubts it will happen quite so fast. He also points out that other
currents in the region would continue to disperse pollutants.

* * * * *

This report appeared in New Scientist on 06 August 2009, at
http://www.newscientist.com/article/mg20327204.800-arctic-ocean-set-to-be-polluted-soup-by-2070.html
For similar stories, visit the New Scientist’s Climate Change Topic Guide
at http://www.newscientist.com/topic/climate-change

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