Abstract
BackgroundCoupled climate-carbon cycle simulations generally show that climate feedbacks amplify the buildup of CO2 under respective anthropogenic emission. The effect of climate-carbon cycle feedback is characterised by the feedback gain: the relative increase in CO2 increment as compared to uncoupled simulations. According to the results of the recent Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP), the gain is expected to increase during the 21st century. This conclusion is not supported by the climate model developed at the A.M. Obukhov Institute of Atmospheric Physics at the Russian Academy of Sciences (IAP RAS CM). The latter model shows an eventual transient saturation of the feedback gain. This saturation is manifested in a change of climate-carbon cycle feedback gain which grows initially, attains a maximum, and then decreases, eventually tending to unity.ResultsNumerical experiments with the IAP RAS CM as well as an analysis of the conceptual framework demonstrate that this eventual transient saturation results from the fact that transient climate sensitivity decreases with time.ConclusionOne may conclude that the eventual transient saturation of the climate-carbon cycle feedback is a fundamental property of the coupled climate-carbon system that manifests itself on a relevant time scale.
Highlights
Coupled climate-carbon cycle simulations generally show that climate feedbacks amplify the buildup of CO2 under respective anthropogenic emission
Starting from the works [1,2], climate-carbon cycle interactions in the global numerical models attain a lot of scientific attention. These and subsequent works [3,4,5,6,7,8,9,10,11,12] have found that an interactive coupling between climate and carbon cycle enhances the build up of the carbon dioxide in the atmosphere, C, in comparison to the hypothetical case when the carbon cycle does not respond to the climate changes
There, it is shown that both versions behave realistically in the 20th century and their projections for the 21st century are basically in line with those obtained in the C4MIP project
Summary
Coupled climate-carbon cycle simulations generally show that climate feedbacks amplify the buildup of CO2 under respective anthropogenic emission. According to the results of the recent Coupled ClimateCarbon Cycle Model Intercomparison Project (C4MIP), the gain is expected to increase during the 21st century. This conclusion is not supported by the climate model developed at the A.M. Obukhov Institute of Atmospheric Physics at the Russian Academy of Sciences (IAP RAS CM). Starting from the works [1,2], climate-carbon cycle interactions in the global numerical models attain a lot of scientific attention These and subsequent works [3,4,5,6,7,8,9,10,11,12] have found that an interactive coupling between climate and carbon cycle enhances the build up of the carbon dioxide in the atmosphere, C, in comparison to the hypothetical case when the carbon cycle does not respond to the climate changes.
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