Planet Has Used Up Half Its 'Carbon Budget': UN Panel

The UN's climate change panel for the first time charted the upper limit of acceptable global carbon emissions today—and we're already halfway to it. Based on an internationally agreed upon goal of keeping temperatures within 3.6 degrees Fahrenheit of their pre-industrial levels, humanity can only allow gas from 1 trillion tons of burned carbon to enter the atmosphere, the Intergovernmental Panel on Climate Change said in its report, according to the New York Times. We're on pace to hit that ceiling in 2040.

The much-anticipated report was released this morning following a furious night of editing, but the substance of it hasn't changed much since a draft was released in August. The report also presents what, according to the BBC, is considered the most comprehensive statement on how climate change works, concluding with 95% certainty that human activity "has been the dominant cause" of the warming trend. That, the AP points out, is as certain as scientists are that cigarettes kill you, and more certain than they are that vitamins improve your health. (More Intergovernmental Panel on Climate Change stories.)