A number of key components of the Earth's climate system could pass their 'tipping point' this century, according to new research led by a scientist at the University of East Anglia.
Published by the prestigious international journal Proceedings of the National Academy of Science (PNAS), the researchers have coined a new term, 'tipping elements,' to describe those components of the climate system that are at risk of passing a tipping point.
The term 'tipping point' is used to describe a critical threshold at which a small change in human activity can have large, long-term consequences for the Earth's climate system.
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 the time it will take them to undergo a major transition are: (1) Melting of Arctic sea-ice (approx. 10 years); (2) Decay of the Greenland ice sheet (more than 300 years); (3) Collapse of the West Antarctic ice sheet (more than 300 years); (4) Collapse of the Atlantic thermohaline circulation (approx. 100 years); (5) Increase in the El Nino Southern Oscillation (approx. 100 years); (6) Collapse of the Indian summer monsoon (approx. 1 year); (7) Greening of the Sahara/Sahel and disruption of the West African monsoon (approx. 10 years); (8) Dieback of the Amazon rainforest (approx. 50 years); (9) Dieback of the Boreal Forest (approx. 50 years).
The paper also demonstrates how, in principle, early warning systems could be established using real-time monitoring and modelling to detect the proximity of certain tipping points.
'Society must not be lulled into a false sense of security by smooth projections of global change,' said Prof. Lenton.
'Our findings suggest that a variety of tipping elements could reach their critical point within this century under human-induced climate change. The greatest threats are tipping of the Arctic sea-ice and the Greenland ice sheet, and at least five other elements could surprise us by exhibiting a nearby tipping point.'