In the Figure above, the three climate sensitivities — 10^th, 50^th and 90^th percentiles — designated by Andronova and Schlesinger (Single probability density function) are combined with the radiative forcings for the A1FI and A1T scenarios. The dashed horizontal lines in both graphs represent the 3.5 ^oC threshold, and the blue shaded area marks the extent to which the two scenarios exceed that 3.5 ^oC threshold. These produce similar projections of warming for the first several decades of the 21^st century, but diverge considerably— especially the high-sensitivity 90^th percentile case — after mid-century. The 50^th and 90^th percentile A1FI cases both exceed a threshold of 3.5 ^oC warming before 2100, and the area shaded in blue is much more dramatic in the fossil intensive scenario than the technological innovation scenario. In fact, at 2100, when the A1T curves are flattening out, the A1FI temperatures are still upwardly sloped — implying yet greater warming in the 22^nd century. Thus, in order to fully assess “dangerous” climate change potential, simulations that cover well over 100 years are necessary since it is widely considered that warming above a few degrees Celsius is likely to be much more harmful than for changes below a few degrees (see IPCC Working Group II, TAR, Chapter 1 and Chapter 19; and climate change impacts:). (Source: Schneider 2003a)