Here's more about the research predicting "higher end" temperature increases.
"Hovering several thousand feet above Earth's surface, in the troposphere—the part of the atmosphere where clouds can form—dry zones play a primary role in the future climate.
The scientists compared the observed relative humidity in the dry zones to 16 different climate models used in the most recent study by the Intergovernmental Panel on Climate Change.
Since we don't have good ways to observe or predict how clouds will form, focus instead on relative humidity, which we can observe. How well do the climate models predict the relative humidity data that has actually been observed?
Fasullo and Trenberth found that the three models that best matched the humidity observations were the same ones that predict the hottest future, with temperatures increasing 8 degrees F before century's end. The least accurate models overpredicted relative humidity and projected lower increases in temperature. Fasullo used the analogy of an eye: 'The dry zones are like the iris of the climate system. With warming, the iris dilates, decreasing cloud cover and allowing in more heat.' Models that don't provide for that expansion of the dry zone fail to accurately depict observed data, he explained."
The article ends with a small equivocation:
Karen Shell, a climate scientist from Oregon State University who was not involved in the research […]: "It's a promising technique. It's one study, but if this relationship holds up, it implies the climate sensitivity is on the higher end of the range."