Scientists have identified potential ‘tipping points’ where abrupt regional climate shifts could occur due to global warming. The scientists analyzed the climate model simulations on which the recent 5th Intergovernmental Panel on Climate Change (IPCC) reports are based. They found evidence of 41 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....