The 2,000-plus page report, written by 209 lead authors, also found it was "unequivocal" that global warming was happening as a result of human actions, and that without "substantial and sustained" reductions in greenhouse gas emissions we will breach the symbolic threshold of 2C of warming, which governments around the world have pledged not to do.
Ban Ki-moon, the UN secretary-general, urged world leaders to pay heed to the "world's authority on climate change" and forge a new global deal on cutting emissions. "The heat is on. Now we must act," he said.
John Kerry, the US secretary of state, said in a statement: "This is yet another wakeup call: those who deny the science or choose excuses over action are playing with fire." "Once again, the science grows clearer, the case grows more compelling, and the costs of inaction grow beyond anything that anyone with conscience or commonsense should be willing to even contemplate," he added.
The IPCC also rebuffed the argument made by climate sceptics that a "pause" for the last 10-15 years in the upward climb of global temperatures was evidence of flaws in their computer models. In the summary for policymakers, published on Friday morning after days of deliberations in the Swedish capital, the scientists said: "Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850. In the northern hemisphere, 1983-2012 was likely the warmest 30-year period of the last 1,400 years."
