Here is a link to the chapter which is causing all the controversy. Out here in Edmonton I haven't been following the blog debates, although at every meal I am asked about carbon taxes and tar sands. (By the way, I believe the Alberta strategy is to pay any forthcoming tax and be profitable enough to keep on producing fossil fuel energy.) My view is to be skeptical of geo-engineering as a solution, for reasons outlined here. In any case it's a question I'll be thinking more about. Among the questions I need to think through more are how bad is it to control global temperature but keep the CO2 in the air, how much acidification of the oceans matters, how geo-engineering affects the variance of global climate, and what the long run looks like if the world becomes "addicted" to the eighteen-mile hose or whatever is used. For a start on the current brouhaha, here is a link to Krugman and Levitt. Mark Thoma offers up other links.
Addendum: This post seems to imply the chapter reproduction is not authorized, so I've taken down the link to the link.