An international team of scientists has identified potential "tipping points" where abrupt regional climate shifts could occur as a result of global warming. In a new study published this week in Proceedings of the National Academy of Sciences (PNAS), the scientists, including Chris Huntingford from the Centre for Ecology & Hydrology, analysed the climate model simulations on which the recent 5th Intergovernmental Panel on Climate Change report was based. They found evidence of more than 30 cases of regional abrupt changes in the ocean, sea ice, snow cover, permafrost and terrestrial biosphere.

Many of these events occur for global warming levels of less than two degrees, a threshold sometimes presented as a safe limit. However, although most models predict one or more abrupt regional shifts, any specific shift typically appears in only a few models.

Examples of detected climate tipping include abrupt shifts in sea ice and ocean circulation patterns, as well as rapid shifts in vegetation and marine productivity. Sea ice abrupt changes are particularly common in the climate simulations. However, various models also predict abrupt changes in other Earth system elements such as tundra permafrost and snow on the Tibetan plateau.

Lead author Professor Sybren Drijfhout of the University of Southampton said it illustrated the high uncertainty in predicting tipping points. He added, "Our results also show that no safe limit exists and that many abrupt shifts already occur for global warming levels much lower than two degrees."

Chris Huntingford, a climate modeller at the Centre for Ecology & Hydrology, was one of the authors of the PNAS study. He said, "We appeal to those designing the CMIP6 (Climate Model Intercomparison) experiment format to consider a requirement for larger ensembles of simulations. This will enable better understanding as to how robust our specific timings are for each identified system tipping point".

Additional information

Paper reference: Sybren Drijfhout, Sebastian Bathiany, Claudie Beaulieu, Victor Brovkin, Martin Claussen, Chris Huntingford, Marten Scheffer, Giovanni Sgubin, Didier Swingedouw. Catalogue of abrupt shifts in Intergovernmental Panel on Climate Change climate models. Proceedings of the National Academy of Sciences, 2015; 201511451 DOI: 10.1073/pnas.1511451112

The University of Southampton issued a press release for this story.

Staff page of Dr Chris Huntingford