With Dr. Willie Soon of the Harvard-Smithsonian Center for Astrophysics, we found that simply predicting that global mean temperatures will not change results in quite small forecast errors. In our validation study that covered the period 1851 to 2007, we compared the no-change forecast with the IPCC global warming forecast that temperatures will climb at a rate of 0.03C per year. We compared the IPCC projection of 0.03C per year with what actually happened after 1850. The errors from the IPCC projection were 12 times larger than no-change benchmark. Consider the accuracy of the no-change model: On average the 50-years ahead forecasts differed by only 0.24C from the global mean temperature as measured by the Hadley Centre in the U. K.
What a clever test! It turns out that the temperature change over the past 150 years is closer to zero than to 4.5 C. Therefore, wait for it…
Based on our analysis, we expect the annual global mean temperature for every year for the rest of the 21st Century to be within plus-or-minus 0.5C of the 2008 mean.
Therefore the sensitivity is zero! Haha! Look, the three lines of code were written by an astrophysicist! Zero! Hahahaha!