Uh oh. Humans Halfway to Causing Dangerous Climate Change.

When human injection of carbon into the atmosphere reaches 1 trillion tons, dangerous climate change with average global warming of more than 2 Celsius degrees will likely occur, a new analysis finds.

And humans are hurrying toward that 1 trillion mark. So far, we’ve added about 520 billion tons of carbon to the atmosphere. With the addition of an estimated 9 billion tons of carbon a year — a number that’s been growing since 1850 — dangerous warming is likely to occur within half a century.

That’s the message from a new paper in the journal Nature, which — along with half a dozen other papers in the issue — provides a simpler way of looking at the climate change problem. What matters is the total amount of carbon that we release into the atmosphere, and focusing on that number as a budget can shape the way policymakers look at the problem, argues Myles Allen, lead author of one of the papers and a climatologist at the University of Oxford.

“The important thing about the cumulative budget is that a ton of carbon is a ton of carbon. If we release it now, it’s a ton we can’t release in 40 years’ time. Every ton we put out is using up a ton of that atmospheric capacity,” Allen told Wired.com. “Reducing emissions steadily over 50 years is much cheaper and easier and less traumatic than allowing them to rise for 15 years and then reducing them violently for 35 years.”