Now that is controversial stuff. Michaels and Balling are saying the planet's warming is linear, and therefore predictable. In Prediction 2, given that we now know the slope, the temperature forecast for the future is easy. We've experienced about 1.0C of global warming since pre-industrial times. 1.8C. Climate modelers claim there are far too many uncertainties to make so bold a forecast.
Reality is certainly much more complicated.
This range is relatively robust to errors in the models' climate sensitivity, rate of oceanic heat uptake or global response to sulphate aerosols as long as these errors are persistent over time. Michaels and Balling's more refined numbers are dead smack in the middle of this range. That kind of confident estimate is not possible using current climate model forecasts. Rather, Allen and colleagues arrived at it using simple statistics, comparing observed temperature patterns for each decade from 1946 to 1996 with the decadal projections of various climate models. Now, we all know the model projections of current climate are not correct.