The warming of the Arctic is releasing toxic chemicals that had been trapped in the ice and cold water, scientists have discovered.
Researchers warn that the amount of poison in the polar region is unknown and its release could undermine global efforts to reduce environmental and human exposure to it. 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 organic pollutants (Pops) and are banned under the 2004 Stockholm convention.
Pops can cause cancer and birth defects and take a long time to degrade. Over past decades, the low temperatures in the Arctic trapped volatile Pops in ice and cold water. But scientists in Canada and Norway have discovered that global warming is freeing them up again. They examined measurements of Pops in the air between 1993 and 2009 at the Zeppelin research station in Svalbaard and the Alert weather station in northern Canada.
After allowing for the decline in global emissions of Pops, the team showed that the toxic chemicals were being remobilised 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 its work provided the first evidence of the remobilisation of Pops in the Arctic. But this was just the beginning of the story, she said. The next step was to find out how much was in the Arctic, how much would leak out and how quickly. —