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Anthropogenic forcing could push the Earths climate system past critical thresholds, so that important components may tip into qualitatively different modes of operation. In the renowned magazine Proceedings of the National Academy of Sciences (PNAS) an international team of researchers describes, where small changes can have large long-term consequences on human and ecological systems.
Society may be lulled into a false sense of security by smooth projections of global change, the researchers around Timothy Lenton from the British University of East Anglia in Norwich and Hans Joachim Schellnhuber from the Potsdam Institute for Climate Impact Research report. Global change may appear to be a slow and gradual process on human scales. However, in some regions anthropogenic forcing on the climate system could kick start abrupt and potentially irreversible changes. For these sub-systems of the Earth system the researchers introduce the term tipping element.
Drawing on a workshop of 36 leading climate scientists in October 2005 at the British Embassy, Berlin, Germany, a further elicitation of 52 experts in the field, and a review of the pertinent literature, the authors compiled a short-list of nine potential tipping elements. These tipping elements are ranked as the most policy-relevant and require consideration in international climate politics.
Arctic sea-ice and the Greenland Ice Sheet are regarded as the most sensitive tipping elements with the smallest uncertainty. Scientists expect ice cover to dwindle due to global warming. The West Antarctic Ice Sheet is probably less sensitive as a tipping element, but projections of its future behavior have large uncertainty. This also applies to the Amazon rainforest and Boreal forests, the El Nio phenomenon, and the West African monsoon. These tippi
|Contact: Uta Pohlmann|
Potsdam Institute for Climate Impact Research (PIK)