I thought I'd give this reference at Stoat a little more exposure: under questioning, Richard Lindzen apparently acknowledged that doubling CO2 would cause a temperature increase of 0.5 - 2 degrees Celsius. The top of his range overlaps with the bottom of the IPCC consensus position, and shifts significantly from his statement almost exactly two years ago that the odds of warming were 50-50.
Right now this is somewhat poorly sourced, but if Lindzen comes clean and verifies, the thin field of true, humans-ain't-doing-nuthin' denialists just got a lot more emaciated. Now who's their hero? Singer? Bolt? Some crazy English viscount?
Even more important, the no-big-deal denialists might have some trouble claiming Lindzen's new view as supportive. Lindzen's upper range is hitting the point where we would want to do something to control emissions, especially since if we don't, CO2 levels will do much more than double.