Public healthMelting ice sheets release toxic pollutants outlawed in 2001
The melting of arctic ice sheets causes the rise in sea levels — but there is another danger: the melting causes dangerous chemicals, including the notoriously toxic DDT, to be freed from Arctic sea ice and snow; the chemical — known as “persistent organic pollutants” (POPs) — were widely used as insecticides and pesticides before being outlawed in 2001; they are extremely tough molecules that take decades to break down in nature; they also bio-accumulate, meaning that as they pass up the food chain, concentrations rise, posing a fertility threat to higher species
If it is not one thing, it is another. Global warming is causing arctic ice sheet to melt, adding more water to the ocean and raising sea levels. Scientists are now warning of another dangerous side-effect of melting sheets: the melting ice causes dangerous chemicals, including the notoriously toxic DDT, to be freed from Arctic sea ice and snow.
The chemical are called the Dirty Dozen — or, more formally “persistent organic pollutants” (POPs) — were widely used as insecticides and pesticides before being outlawed in 2001. Yahoo! News reports that they are extremely tough molecules that take decades to break down in nature. They also bio-accumulate, meaning that as they pass up the food chain, concentrations rise, posing a fertility threat to higher species.
What is more, they are insoluble in water and easily revolatilize, so can swiftly move from soil and water to the atmosphere in response to higher temperatures.
The study, published in the scientific journal Nature Climate Change, looked at atmospheric concentrations of three chemicals — DDT, HCH, and cischlordane — monitored between 1993 and 2009 at a station in Norway’s Svalbard Islands and at another in the Canadian Arctic.
The scientists found a long-term downward trend in primary emissions after the Stockholm Convention banned production and trade in the Dirty Dozen.
A more complex and disturbing picture emerged, however, when the same data was crunched through a simulation of the effect of global warming on POP concentrations.
It found a slight rise in secondary emissions from POPs that had been locked in Arctic ice and snow but were now being gradually released because of warming.
“A wide range of POPs have been remobilized into the Arctic atmosphere over the past two decades as a result of climate change,” said the study, led by Jianmin Ma of the agency Environment Canada in Toronto.
Arctic warming “could undermine global efforts to reduce environmental and human exposure to these toxic chemicals,” the study warned.
Pollution specialist Jordi Dachs of the Institute of Environmental Assessment and Water Research in Barcelona, Spain, said this news was grim.
The Arctic has been hit two or three times harder than other parts of the planet for warming, and thus could be the forerunner for POP releases from other stores, including the soil and deep ocean.
“It seems likely that persistent pollutants will affect the environment on even longer timescales than currently assumed,” said Dachs. “The remobilisation of pollutants generated by our grandparents… are unwanted witnesses to our environmental past that now seem to be ‘coming in from the cold.’”
— Read more in Jianmin Ma et al., “Revolatilization of persistent organic pollutants in the Arctic induced by climate change,” Nature Climate Change (24 July 2011) (doi:10.1038/nclimate1167); and Jordi Dachs, “Atmospheric science: Coming in from the cold,” Nature Climate Change (24 July 2011) (doi:10.1038/nclimate1175) (sub. req.)
