The paper reports results of model experiment comparing world with and without the deforestation that occurred from 1850 until the 2000's. (forestsnews.cifor.org)
For model experiments, anomalies are relative to the SST forcing (1920 - 1929) experiment. (giss.nasa.gov)
The shorter, regional model experiments are much smaller and take between a few days and a month to run. (climateprediction.net)