Figure 2 -

Comparison of observed changes in global mean surface temperature with results simulated by climate models using natural and anthropogenic forcings. Decadal averages of observations are shown for the period 1906–2005 (black) plotted against the centre of the decade and relative to the corresponding average for 1901–1950. The blue band shows the 5–95% range for 19 simulations from five climate models using only the natural forcings due to solar activity and volcanoes. The rose-colored band shows the 5–95% range for 58 simulations from 14 climate models using both natural and anthropogenic forcings¹. Added to the figure are I-beams denoting uncertainties. The range of the modelled increase in global mean surface temperature over the twentieth century (red) — 0.5 to 1.0 °C, or a factor of 2 — is smaller than that of the IPCC estimate for the global mean forcing (green), given in Fig. 1, which is a factor of 4.