ScienceDaily (Feb. 10, 2010) — A new University of California, Davis, study by a top ecological forecaster says it is harder than experts thought to predict when sudden shifts in Earth's natural systems will occur -- a worrisome finding for scientists trying to identify the tipping points that could push climate change into an irreparable global disaster.
http://www.sciencedaily.com/releases/2010/02/100209191445.htm