Matthews, H. DamonKeith, David2021-04-262007-05-04H. Damon Matthews, & David W. Keith. (2007). Carbon-cycle feedbacks increase the likelihood of a warmer future. Geophysical Research Letters, 34(9).0094-8276https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37367391Positive carbon-cycle feedbacks have the potential to reduce natural carbon uptake and accelerate future climate change. In this paper, we introduce a novel approach to incorporating carbon-cycle feedbacks into probabilistic assessments of future warming. Using a coupled climate- carbon model, we show that including carbon-cycle feedbacks leads to large increases in extreme warming probabilities. For example, for a scenario of CO2 stabilization at 550 ppm, the probability of exceeding 2°C warming at 2100 increased by a factor of between 1.7 and 3, while the probability of exceeding 3°C warming increased from a few percent to as much as 22%. CO2 fertilization was found to exert little influence on the amount of future warming, since increased carbon uptake was partially offset by fertilization-induced surface albedo changes. The effect of positive carbon-cycle feedbacks on the likelihood of extreme future warming must be incorporated into climate policy-related decision making.en-UScarbon cycle feedbacksfuture warming probabilityclimate change uncertaintyJournal Article2021-04-2610.1029/2006gl028685