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No going back for Arctic

When Arctic sea-ice levels finally hit the anticipated record low this week, I felt a mixture of fear and panic (Arctic sea-ice levels on the verge of record low, GW, 31 August). Trend lines on graphs of sea-ice extent show the Arctic could be ice-free as early as September 2015 and almost certainly by 2020. With more exposed ocean absorbing more radiation and less ice to reflect it, a positive feedback mechanism has been set in train.

There are already reports of extensive methane releases from collapsing subsea permafrost on the East Siberian Arctic Shelf (ESAS). Methane is, of course, a potent greenhouse gas. Now a study published in the journal Nature reveals that a less studied form of permafrost, Yedoma, along the 7000 km coast of northern Siberia, is releasing ten times more carbon into the Arctic Ocean than previously thought. Not only is the Yedoma permafrost thawing in the higher temperatures, it is also subject to enhanced wave and wind erosion brought on by the longer ice-free season, causing it to collapse and release even more methane.

Regrettably, President Obama has now given permission to Shell to drill for oil off the northern Alaskan coast in protected habitat critical to the survival of polar bears. This, even before a vital oil-spill containment vessel received its certification. The decision puts wildlife in terrible danger as any oil spill will be almost impossible to clean up. As the Center for Biological Diversity says: "Once the Arctic is ruined, there's no going back. Unique animals like polar bears, yellow-billed loons, eiders, walruses, whales and ice seals that have evolved over millions of years to survive in this frozen wilderness -- and nowhere else -- will be condemned to extinction."

Jenny Goldie, Michelago, NSW, Australia