5% Chance? No Freaking Way

Climate Skeptic: 5% Chance? No Freaking Way

Via William Biggs, Paul Krugman is quoting a study that says there is a 5% chance man's CO2 will raise temperatures 10C and a 1% chance man will raise global temperatures by 20 Celsius. The study he quotes gets these results by applying various statistical tests to the outcomes from the IPCC climate models.

I am calling Bullshit.
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What climate alarmists will argue is that these curves are not continuous. They believe that there is some point out there where the feedback fraction goes above 100%, and thus the gain goes infinite, and the temperature runs away suddenly. The best example is fissionable material being relatively inert until it reaches critical mass, when a runaway nuclear fission reaction occurs.

I hope all reasonable people see the problem with this. The earth, on any number of occasions, has been hotter and/or had higher CO2 concentrations, and there is no evidence of this tipping point effect ever having occurred. In fact, climate alarmists like Michael Mann contradict themselves by arguing (in the infamous hockey stick chart) that temperatures absent mankind have been incredibly stable for thousands of years, despite numerous forcings like volcanoes and the Maunder Minimum. Systems this stable cannot reasonably be dominated by high positive feedbacks, much less tipping points and runaway processes.