According to Weitzman, the IPCC (International Panel on Climate Change) has grossly underestimated the severity of the low probability alternatives in its climate forecasts.
IPCC is predicting that doubling the carbon dioxide in the atmosphere could yield temperature increases of 3.5F (2 C) to 8F (4.5 C) by the end of this century, with a best guess of about 5.5F (3 C). That's with a two-thirds probability – the peak of the bell curve.
That's scarey enough, but when we look at the tails of the bell curve, things get even more disconcerting.
According to Weitzman, there is a five per cent probability of warming greater than 18F (10 C) by the end of this century and a one per cent probability of warming greater than 36F (20 C).
Temperature increases in those ranges would render much of the Earth's surface uninhabitable by human beings.
Climate scientists James Hansen has called for a global carbon tax to control global warming, with the proceeds distributed to everyone as a social dividend or basic income grant.
I have posted a petition on Care2 calling for a worldwide referendum on such a carbon tax. You can view the petition (and hopefully sign it) at http://www.thepetitionsite.com/286/384/042/petition-for-a-referendum-on-a-global-carbon-tax/