Dangerous climate change is a term introduced by the 1992 UN Framework Convention on Climate Change - the treaty that led to the Kyoto protocol. In general terms, it refers to climate change of sufficient severity that it will have a major effect on societies, economies and the wider environment. The definition of what that level is varies, but Defra, for example, defines it as a rise in average global surface temperatures of 1-3 ºC (taking pre-industrial revolution average surface temperatures as the base).