There is an alarming message in a major new report on climate change, a draft of which the New York Times obtained on Tuesday. The United Nations’ Intergovernmental Panel on Climate Change, a group of leading scientists who review the latest and best available research, say we are dangerously close to the day when it will no longer be possible to limit global warming to 3.6 degrees Fahrenheit (2.0 degrees Celsius) by mid-century—something that world leaders have pledged to do.

Of course, the pledge might already be delusional, given that countries continue to burn fossil fuels at an unprecedented rate. In the first decade of the twenty-first century, emissions grew at 2.2 percent per year. That’s nearly twice as much as they increased in the three decades that preceded it. And it’s no secret why. While emissions have been slowing in industrialized countries, that hasn’t offset the growth in emissions from China and India. The report also finds companies and countries are sitting on four times more of the fossil fuels than the world should be burning if it reasonably expects to keep the worst of global warming at bay. In other words, countries will have the opportunity to fill the atmosphere with way too many greenhouse gases—the question is whether they can somehow resist the temptation.

This latest draft is a revision of an earlier one, which Reuters obtained in August. That version suggested that we would need drastic greenhouse gas cuts of 40 to 70 percent worldwide by 2050, in order to keep to the 3.6 degrees target. What that means in plain language is that countries like the U.S. and China would need to start confronting the economic costs of switching away from fossil fuels now, in order to avoid a much more dangerous (and costly) future.

Why is 3.6 degrees so important? Most research today looks at the consequences warming on this scale. It’s not a sure thing, as the scientists acknowledge. The actual increase would fall somewhere within a fairly broad range. But even more optimistic scenarios, in which the planet ends up warming little, would entail more extreme weather, acidic oceans, and a changing ecosystem. On the other end of the spectrum are some really nightmarish possibilities. At eight degrees of warming, which the draft report sees as a distinct possibility, the effects would include vast ice sheets in Greenland and Antarctica destabilizing completely, changing coastal civilization as we know it as sea levels rise by 23 feet. Recent studies suggest the western Antarctic ice sheet may already be past the point of “irreversible” melting, so this scenario is not far-fetched.

The clock is ticking and the nations of the world are … well … it remains to be seen what the nations of the world will do. Next month the United Nations will hold a Climate Summit. It’s the prelude to a much bigger round of international negotiations, in Paris in 2015. President Barack Obama seems to be brokering a climate accord ahead of these talks—seen as the best chance coordinate and agree upon the greenhouse gas cuts needed—that would sidestep Republican opposition by not requiring Senate ratification. Because as this new report indicates, waiting another day to take action on climate—let alone a whole year—is tempting fate.