Of course, this is just a bunch of pointy head liberals from some backwoods school call MIT talking, so what the hell do they know? Far better to put faith in the yapping of an unknown poster on and internet board.
http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt169.pdf
Changes in GHG emissions and carbon uptake lead to a significant increase of both the lower
bound of the 90% range and also the median forcing compared to the results of Webster et al.
(2003). The probability of the radiative forcing being less than 5.0 W/m2 is about 45% according
23
to Webster at al. (2003) but less than 1% according to our new study. At the same time the upper
bounds of the 90% ranges differ by only 0.6 W/m2 between the two studies. In fact the new
upper 90% bound on the forcing due to GHGs (Table 1) only is even lower than the one in
Webster et al. (2003). The slightly higher value of the upper 90% bound for the total forcing is a
result of different changes in sulfate aerosol loading and the fact that forcing associated with
changes in black carbon aerosol was not taken into account by Webster et al. (2003). The total
forcing includes contributions from changes in GHGs, sulfate aerosol, tropospheric ozone as well
as, in present study, black carbon. As shown in section 3.2, use of the revised probability
distributions for the climate parameters leads to larger surface warming and smaller thermal
expansion of the ocean for a given forcing (Figure 3). This effect together with the differences in
radiative forcing described above result in a significantly higher increase in SAT (Figure 8b and
Table 1) than was projected by Webster et al. (2003). While the upper 90% bound for surface
warming projected in this study is noticeably larger than in Webster et al. (2003), (7.4oC instead
of 4.6oC), the changes in the lower part of the projected range are even more significant.
According to Webster et al. (2003) there was a 40% probability of SAT increasing by less than
2oC by the end of 21st century relative to 1990 for the “business-as-usual” emissions scenario, in
the present study surface warming exceeds 2oC in all 400 simulations. We will compare our
projections of possible climate change with projections given in the IPCC AR4 in section 4.4.
