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Climate change could release toxins trapped in ice

Tuesday, July 26, 2011
Ice covering the ocean surface at lower Baffin Island, area around Hudson Strait and the Labrador Sea.

(AP Photo)

Despite a global decrease in the production of certain toxic chemicals, we may be in for an onslaught.

That's because rising global temperatures are causing the release of persistent organic pollutants, such as DDT and PCBs, which have been locked in arctic ice for more than half a century.

Although the chemicals were created to provide societal benefits, such as killing mosquitoes and protecting crops, it didn't take long for scientists to see they were having devastating effects on the environment.

Studies have shown many of these chemicals can cause cancer, birth defects and other health problems. And they don't just wash away. Persistent organic pollutants, as the class of chemicals is known, stick around for decades before finally breaking down.

They also are attracted to fatty tissue in animals and pass through the food chain from one animal to the next.

Recognizing the dangers of these chemicals, dozens of wealthy nations joined forces in 2001 to ban 12 of them by signing the Stockholm Convention on POPs (persistent organic pollutants). Yet since that ban, scientists had noticed localized upticks in atmospheric concentrations of these chemicals, especially over the Arctic.

These reports inspired a team of Canadian scientists to see whether climate change was a factor. They went back into the archives of Arctic atmospheric data collected at the Zeppelin Mountain Air Monitoring Station in Norway and the Alert Station in northern Canada.

They found that since the beginning of the century, higher levels of these toxins were correlated with higher temperatures and decreased sea ice. In years when the temperatures were lower and pack ice more extensive, the levels of toxins also were lower.

Their study appeared in the online edition of the journal Nature Climate Change.

"These chemicals are semi-volatile, meaning they don't stay in the air forever," Hayley H.N. Hung, co-author of the study and a researcher with Environment Canada, told Reuters' Solve Climate News, an environmental news wire.

"They drop down and get deposited into different materials. The organically rich, cold soil in the Arctic is a good trap for these chemicals," she said. "And POPs in the polar oceans are capped by sea ice, which literally puts a lid on the pollutants to keep them in place."

When the sea ice melts, she said, the toxins are "uncapped" and re-enter the atmosphere.

The researchers then developed a model to predict the amount of chemicals that could be released over the next few decades.

Their results show that there will be significant atmospheric increases in these chemicals over the next 50 years, with unknown effects. But the researchers worry it could be disastrous for wildlife and human health.

"If the mobility of these compounds is increased by climate change, it could have significant implications for ecosystems and human health," said Jordi Dachs, a researcher at the Institute of Environmental Assessment and Water Research in Barcelona, Spain. Dachs was not involved in the research.

"The remobilization of pollutants generated by our grandparents -- pollutants that were banned decades ago ... now seem to be 'coming in from the cold,' " Dachs said.

Story courtesy of our media partners at California Watch (A Project of the Center for Investigative Reporting)


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