Bioclimate.org: Tipping elements in the Earth’s climate system

Authors	Lenton T. , Held H. , Kriegler E. , Hall J.W. , Lucht W. , Rahmstorf S. , Schellnhuber H.J.
Source	Proceedings of the National Academy of Sciences of the United States of America (PNAS) (103)
Type	P - Paper (1845)
Peer Review	2 - Medium (1877)
Audience	S - Specialist (2421)
Pages	1786-1793
Journal Number	105
Notes	The term ‘‘tipping point’’ commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term ‘‘tipping element’’ to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.