(trouble is 35 is for carbon dioxide concentration, and 65 is for forcing, so if that's the calculation it was indeed a typo in a spreadsheet) Actually CO2 as a percentage of all radiative forcing would be: 43/65 * 100 = 66 % You messed up the link (I think) so that it actually leads back to this page rather than the FAQ section http://illconsidered.blogspot.com/2006/02/whats-wrong-with-warm-weather.html Never mind, as you know, I don't think the costs imposed by that change are large, not as long as sea level rise is only 50 cm over a hundred years (and the midpoint for the
scenarios I consider most policy relevant, ie those excluding lots of coal burning after 2050, is
somewhat lower still) and the change in «weather
extremes» largely amounts to nothing more than what would be expected from moving south a few hundred kilometres.