Posted by: climatewonk | February 12, 2008

Tipping Points

An article on climate change and tipping points from Science Daily:

In this new research, lead author Prof Tim Lenton of the University of East Anglia (UEA) and colleagues at the Postdam Institute of Climate Impact Research (PIK), Carnegie Mellon University, Newcastle University and Oxford University have drawn up a shortlist of nine tipping elements relevant to current policy-making and calculated where their tipping points could lie. All of them could be tipped within the next 100 years. The nine tipping elements and a prediction of the time it would take them to undergo a major transition are:

Melting of Arctic sea-ice (approx 10 years)
Decay of the Greenland ice sheet (more than 300 years)
Collapse of the West Antarctic ice sheet (more than 300 years)
Collapse of the Atlantic thermohaline circulation (approx 100 years)
Increase in the El Nino Southern Oscillation (approx 100 years)
Collapse of the Indian summer monsoon (approx 1 year)
Greening of the Sahara/Sahel and disruption of the West African monsoon (approx 10 years)
Dieback of the Amazon rainforest (approx 50 years)
Dieback of the Boreal Forest (approx 50 years)
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 Niño phenomenon, and the West African monsoon. “These tipping elements are candidates for surprising society by exhibiting a nearby tipping point,” the authors state in the article that is published in PNAS Online Early Edition. The archetypal example of a tipping element, the Atlantic thermohaline circulation, could undergo a large abrupt transition with up to ten percent probability within this century, according to the UN climate report from 2007.

Given the scale of potentially dramatic impacts from tipping elements the researchers anticipate stronger mitigation. Concepts for adaptation that go beyond current incremental approaches are also necessary. In addition, “a rigorous study of potential tipping elements in human socio-economic systems would also be welcome,” the researchers write. Some models suggest there are tipping points to be passed for the transition to a low carbon society.

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