The temperature change you see on the right-hand side of En-ROADS is the change in global temperature from pre-industrial times (averaging over the period 1850-1900). We use data on temperature change from NASA's GISTEMP and the Met Office Hadley Centre's HadCRUT3 averaged over 1850-1900 to obtain the reference pre-industrial temperature. For more information, you can take a look at our En-ROADS Reference Guide.