Pakistan floods released stored toxic chemicals

Catherine Brahic in New Scientist: The floods that tore through Pakistan earlier this year, affecting 20 million people, released some 3000 tonnes of dangerous chemicals into the environment. A report due to be published next year will warn that the event was not a one-off. Its findings were presented at the climate negotiations in Cancún, Mexico, yesterday.

The long-lived chemicals, known collectively as persistent organic pollutants (POPs), include several banned pesticides and the insect repellent DDT. They are dispersed around the planet by atmospheric patterns, do not degrade naturally, and are linked to hormonal, developmental and reproductive disorders, and increased risk of diabetes, cancer and dementia.

Climate Change and POPs Inter-Linkages, published by the UN Environment Programme, is the first study to look at how climate change will affect POPs, which are regulated under the UN Stockholm convention. It found that climate change increases the risks posed in several ways. Both measurements and models show that as evaporation increases with warmer temperatures, more of the chemicals are released from the land masses, rivers and lakes where they are stored. Once in the atmosphere, they can travel great distances.

Likewise, glaciers lock away POPs, preventing them from causing more harm. But data shows that as they are melting with global warming, their toxic load is being re-mobilised….