Choosing that precise lowest year is «cherry - picking» the start date, ignoring the variation in a way to mazimize the statement of early century warming. (realclimate.org)
In fact, one of the realizations (upper right) happens to capture considerable early century warming, peaking near mid-century in high northern latitudes, comparable to that observed. (gfdl.noaa.gov)
Basically, climate scientists ran their models against history, and found that even with their SO2 plug, they still didn't match well — they were underestimating early century warming and over-estimating late century warming. (climate-skeptic.com)