Bummer: Carbon dioxide may kill billions of people

Climate Change: Still Worse Than You Think | Mother Jones

a doubling of CO2 in the atmosphere might produce a temperature increase of six to eight degrees Celsius, not the mere three degrees Celsius most commonly estimated.

This is just one model. There are lots of parameters to fit, there are only two glacial intervals to test, and the error bars are fairly large. In other words, it might be wrong. But it's one more data point in an increasing series of data points suggesting that climate change is worse than we thought—though "worse" is something of an understatement. Six degrees isn't just a bit warmer here and there; it's a global catastrophe that would likely produce mass extinctions, dead oceans, large-scale desertification, coastal cities underwater, and billions dead.