Good news & bad news time: the good news is, climate researchers have come up with an improved method for predicting the range of temperature effects from continued greenhouse gas concentration in the atmosphere; the bad news is, the low end of the predicted rise in temperature just went up by a degree, from 1.4°C to 2.4°C. Nature reports that a group at the Hadley Centre for Climate Prediction and Research have devised a method which better accounts for the atmospheric factors (such as cloud reflection of sunlight) which don't yet have precise values, only informed estimates.
The results are still a range of temperatures, but a range that does not depend on any of the informed guesses being exactly right. The new method predicts a hundred year rise in global average temperature of 2.4°-5.4°C. The previous range, from the IPCC, was a 1.4°-5.8°C increase. While this does mean that the high end of the range dropped by four-tenths of a degree, the full-degree jump at the low end is of greater concern.