Arctic Ocean more at risk of acidification than Antarctic: new research

Changes likely to hit marine life earlier in the Arctic than in the Antarctic


The Arctic and the Antarctic are at different ends of the planet — but that’s not the only difference: the Arctic Ocean is more vulnerable to human-induced changes than the Antarctic Ocean, new research suggests.

After comparing sites in both oceans, scientists from Dalhousie Univerity in Halifax found the Arctic Ocean to be more acidic, warmer during the summer months, and have fewer nutrients. Those differences also account for the differences in vulnerability, they say, in Nature’s Scientific Reports.

Both polar oceans are sensitive to increasing global temperature and increasing concentrations of atmospheric carbon dioxide, notes a media release about the new research.

But the scientists believe excess surface nutrients in the Antarctic may help reduce the extent of ocean acidification in that area.

This means the Arctic system may be more vulnerable to future changes including ocean acidification, they said.

Ocean acidification occurs because some of carbon dioxide spewed into the atmosphere from the burning of fossil fuels dissolves in the ocean.

There, carbon dioxide reacts with water to produce an acid, called carbonic acid, which causes the oceans to become more acidic.

Scientists have already determined that the surface waters of Arctic Ocean are corrosively acidic during the ice-free season and that acidification happens faster in the Arctic Ocean because cold water absorbs more carbon dioxide than warm water.

As well, the increasing supply of fresh water supplied to the sea in the Arctic from rivers and melting ice, reduces the capacity of the ocean in the region to neutralize acidification, scientists have found.

The Dalhousie team expects changes in acidity to have “detrimental effects for shell-forming species” (as other studies have suggested) and “therefore potentially for human food supply.”

That’s because as seawater becomes more acidic and fresher, there’s less of the minerals and carbonate needed for shell formation.

These effects will take place much earlier in the populated Arctic regions than in the unpopulated Antarctic regions, they predict.

Their conclusions echo those of a recent Arctic Marine Assessment Progamme report which concluded that marine ecosystems in the Arctic are “very likely to experience significant changes due to ocean acidification.”

At the Arctic Council’s Kiruna ministerial meeting last May, ministers said in their Kiruna Declaration that they welcomed the Arctic Ocean acidification assessment.

They noted “with concern the potential impacts of acidification on marine life and people that are dependent on healthy marine ecosystems.”

And they recognized that “carbon dioxide emission reductions are the only effective way to mitigate ocean acidification,” and requested the Arctic States “to continue to take action on mitigation and adaptation and to monitor and assess the state of Arctic Ocean acidification.”

Nunatsiaq Online, 21 August 2013. Article.

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