evidence: Hansen, whose testimony to the US Senate in 1988 is cited as the first high-profile revelation of global heating, warned in a statement with two other scientists that the world was moving towards a "new climate frontier" with temperatures higher than at any point over the past million years, bringing impacts such as stronger storms, heatwaves and droughts. The world has already warmed by about 1.2C since mass industrialization, causing a 20% chance of having the sort of extreme summer temperatures currently seen in many parts of the northern hemisphere, up from a 1% chance 50 years ago, Hansen said. [...] Should global temperatures rise by a further 1C or more, which is widely predicted to happen by the end of the century barring a drastic reduction in emissions, Huber said Hansen was "broadly correct" that the world will be plunged into the sort of warmth not seen since 1-3m years ago, a period of time called the Pliocene.