Melting Arctic ice is releasing banned toxins, warn scientists. Unknown amount of trapped persistent organics pollutants poses threat to marine life and humans as temperatures rise
The chemicals seeping out as temperatures rise include the pesticides DDT, lindane and chlordane as well as the industrial chemicals PCBs and the fungicide hexachlorobenzene (HCB). All of these are known as persistent organics pollutants(POPS), and are banned under the 2004 Stockholm convention
Pops can cause cancers and birth defects and take a long time to degrade. Over past decades, the low temperatures in the Arctic trapped POPS in ice and cold water. But scientists in Canada and Norway have discovered that global warming is freeing the Pops again. They examined measurements of Pops in the air between 1993 and 2009 at the Zeppelin research station in Svalbaard and Alert weather station in northern Canada.
After allowing for the decline in global emissions of Pops, the team showed that the toxic chemicals are being remobilized by rising temperatures and the retreat of the sea ice, which exposes more water to the sun. The scientists' work is published in the journal Nature Climate Change.
Hayley Hung, at the air quality research division of Environment Canada and one of the team, said their work provided the first evidence of the remobilization of Pops in the Arctic.
"But this is the beginning of a story," she said. "The next step is to find out how much is in the Arctic, how much will leak out and how quickly."
The fate of the frozen Pops depends on the speed of warming in the Arctic – it is currently heating up much more quickly than lower latitudes – as well as how the chemicals interact with snow and rain. Pops accumulate in fats and are therefore concentrated up the food chain, but Hung cautions that food chains themselves in the Arctic may be altered by climate change.