Turns out that computer models may have been underestimating the severity of climate change.
"More than two dozen major climate models are being used to forecast global warming from rising greenhouse gas emissions—notably how much warming will occur when atmospheric carbon dioxide doubles from preindustrial times. At current rates that unhappy milestone will be reached well before 2100. So which models are more accurate?
For decades the leading models have predicted an average rise of 5 degrees Fahrenheit (2.7 degrees Celsius), with models on the low end predicting a rise of 3 degrees F (~1.6 degrees C) and those on the high end predicting 8 degrees F (5.3 degrees C). Now a new analysis in the leading journal Science suggests that the higher end forecasts are more accurate."