Table 1.

Carbon cycle feedbacks in the Earth System that could accelerate global warming

FeedbackStrength of feedback by 2100,* °CRefs. (SI Appendix, Table S2 has more details)
Permafrost thawing0.09 (0.04–0.16)2023
Relative weakening of land and ocean physiological C sinks0.25 (0.13–0.37)24
Increased bacterial respiration in the ocean0.0225, 26
Amazon forest dieback0.05 (0.03–0.11)27
Boreal forest dieback0.06 (0.02–0.10)28
 Total0.47 (0.24–0.66)
  • The strength of the feedback is estimated at 2100 for an ∼2 °C warming.

  • * The additional temperature rise (degrees Celsius) by 2100 arising from the feedback.