Melting Arctic ice releasing banned toxins

Damian Carrington in the Guardian (UK): The warming of the Arctic is releasing a new wave of toxic chemicals that had been trapped in the ice and cold water, scientists have discovered. The researchers warn that the amount of the poisons stockpiled in the polar region is unknown and their release could "undermine global efforts to reduce environmental and human exposure to them".

The chemicals seeping out as temperatures rise include the pesticides DDT, lindane and chlordane, made infamous in Rachel Carson's 1962 book Silent Spring, as well as the industrial chemicals PCBs and the fungicide hexachlorobenzene (HCB). All of these are know as persistent organics pollutants (Pops), and are banned under the 2004 Stockholm convention.

Pops can cause cancers and birth defects and take a very long time to degrade, meaning they can be transported for long distances and accumulate over time. 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 the Pops once 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....

The sea ice atop the Arctic Ocean can—as shown in this photograph from July 12, 2011—look more like swiss cheese or a bright coastal wetland. As ice melts, the liquid water collects in depressions on the surface and deepens them, forming melt ponds. These fresh water ponds are separated from the salty sea below and around it, until breaks in the ice merge the two. Shot by the NASA-funded ICESCAPE mission—Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment.