29 May 2024
 | 29 May 2024
Status: this preprint is open for discussion.

Carbon-climate feedback higher when assuming Michaelis-Menten kinetics of respiration

Christian Beer

Abstract. Earth system models simplify complex terrestrial respiration processes assuming a first-order chemical reaction or assuming a Michaelis-Menten kinetics. The epistemic uncertainty related to the respective mathematical representations is unclear. Using a simplified model of biogeochemical feedbacks to climate, we show that the terrestrial carbon-climate feedback is more than 35 % higher, and hence the remaining carbon budget to keep global warming below 2 °C is 89–158 Pg C higher, when assuming Michaelis-Menten kinetics instead of first-order kinetics, but these differences depend on the underlying emission scenario. These results show the importance of an increased understanding of the mathematical model structure of respiration processes in Earth System Models for more reliably projecting future carbon dynamics and climate, related feedback mechanisms, and hence to estimate a valid remaining anthropogenic carbon budget.

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Christian Beer

Status: open (until 17 Jul 2024)

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Christian Beer
Christian Beer


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Short summary
Fauna and flora respires carbon dioxide into the atmosphere, which is a major carbon flux into the atmosphere. The underlying biochemical processes are complex, and we generalize them either assuming a first order chemical reaction of carbon and oxygen to carbon dioxide, or assuming enzymatic reactions. Here, we show that these assumptions lead to large differences in estimating the carbon-climate feedback until 2100 and the remaining carbon budget to keep warming below 2 degrees C.