Fig. 3.
Fraction of total surface warming (warming caused by the combined CO2-radiative and physiological effects) associated with the physiological forcing of CO2. The fractional contribution of warming due to CO2-physiological forcing is calculated as the ratio between changes in surface air temperature in response to the CO2-physiological forcing and temperature change in response to the combined effect of CO2-radiative and physiological forcing. These changes are averaged annual mean values in response to a doubling of atmospheric CO2 calculated from the last 70-yr results of 100-yr simulations. Hatched areas are regions where changes are not statistically significant at the 5% level using the Student t-test.