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Dynamical response of precipitation reveals an emergent constraint on tropical circulation

Presentation Date
Monday, December 11, 2023 at 4:50pm - Monday, December 11, 2023 at 5:00pm
Location
MC - 3008 - West
Authors

Author

Abstract

Changes in the hydrological cycle under climate change have significant implications for water resources, agriculture, and ecosystems. The large uncertainty in precipitation projections by Earth system models remains a major challenge for climate change impact assessment and climate action. A key parameter of the hydrological cycle changes is the future hydrological sensitivity (HS), which is the sensitivity of global-mean precipitation to temperature in climate change projections. HS has a large model uncertainty, in both Coupled Model Intercomparison Projects 5 and 6. While previous attempts to constrain HS indicate a possible link between HS under climate change versus natural variability, a robust constraint of future HS has not yet been found. In this study, we present an emergent constraint on HS via a decomposition into its dynamical and thermodynamical components. Model uncertainty in HS under both natural variability and climate change arises from the dynamical component, which exhibits similar spatial patterns between the two regimes. Motivated by this inter-model relationship, we investigate the sensitivity of atmospheric circulation anomalies to temperature. This yields an emergent constraint on the weakening of the tropical atmospheric overturning circulation under climate change. This further allows us to constrain the spatial pattern of the dynamical contribution to HS.

Funding Program Area(s)