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GLOBAL
Arctic about to tip world climate change
An international team of researchers has issued a stark warning about the perils the world faces in the near future because of mounting evidence confirming the carbon dioxide effects of a 5º C increase in the temperature of the Arctic Ocean.

Rapid melting of ice in Greenland and the Arctic Ocean last year showed catastrophic acceleration in 2012, qualifying the effects in the Arctic as “dangerous climate change” under the UN Climate Convention.

The researchers, from Australia, Norway, Spain and Sweden, conducted a series of eight cruises between July 2007 and July 2012 to assess the annual metabolic balance of Arctic plankton communities. This determines their role as carbon dioxide (CO2) sinks or sources and was resolved for the first time.

The five-year-long research revealed that the two-week spring algal bloom occurring each April, as the Arctic emerges from its winter darkness and the sea-ice starts to thin, is so productive it can fuel the food web for the entire year and remove significant amounts of CO2 from the atmosphere annually.

But experiments involving temperature manipulations conducted in the Svalbard Islands, about 650 kilometres north of mainland Europe, indicated that the plankton community switches from acting as a sink to becoming a source of atmospheric CO2 as seawater temperatures exceed 5º C.

The researchers noted that this temperature would be regularly observed in the European sector of the Arctic Ocean over coming decades.

“Warmer temperatures enhance respiration rates by plankton organisms, particularly bacteria, leading to a shift in the size of photosynthetic plankton, which decompose quickly, and results in a major release of CO2 from excess respiration,” the researchers say.

In a paper published last week in Biogeosciences, an open access journal of the European Geosciences Union, the scientists note that model analyses of polar food webs have shown that plankton are particularly vulnerable to disturbances that can trigger a cascade of extinctions in the ecosystem.

The researchers will return to the Arctic for oceanographic cruises next month and in July, as well as conducting a coastal experimental campaign in September in Greenland.

The Norwegian Research Council last week announced a grant of US$4 million to fund further Arctic work by the team, including the Norwegian collaborators at Tromsø University.

The team’s leader and director of the University of Western Australia’s Oceans Institute is Professor Carlos M Duarte. He will also attend a workshop at the White House in Washington DC late next month to contribute to formulating a large research project on the future of the Arctic.
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