19 Oct 2020

19 Oct 2020

Review status: a revised version of this preprint was accepted for the journal ESD and is expected to appear here in due course.

Robust increase of Indian monsoon rainfall and its variability under future warming in CMIP-6 models

Anja Katzenberger1,2, Jacob Schewe1, Julia Pongratz2,3, and Anders Levermann1,4,5 Anja Katzenberger et al.
  • 1Potsdam Institute for Climate Impact Research, Potsdam, Germany
  • 2Ludwig-Maximilian University, Munich, Germany
  • 3Max Planck Institute for Meteorology, Hamburg, Germany
  • 4LDEO, Columbia University, New York, USA
  • 5Potsdam University, Potsdam, Germany

Abstract. The Indian summer monsoon is an integral part of the global climate system. As its seasonal rainfall plays a crucial role in India's agriculture and shapes many other aspects of life, it affects the livelihood of a fifth of the world's population. It is therefore highly relevant to assess its change under potential future climate change. Global climate models within the Coupled Model Intercomparison Project Phase 5 (CMIP-5) indicated a consistent increase in monsoon rainfall and its variability under global warming. Since the range of the results of CMIP-5 was still large and the confidence in the models was limited due to partly poor representation of observed rainfall, the updates within the latest generation of climate models in CMIP-6 are of interest. Here, we analyse 32 models of the latest CMIP-6 exercise with regard to their annual mean monsoon rainfall and its variability. All of these models show a substantial increase in June-to-September (JJAS) mean rainfall under unabated climate change (SSP5-8.5) and most do also for the other three Shared Socioeconomic Pathways analyzed (SSP1-2.6, SSP2-4.5, SSP3-7.0). Moreover, the simulation ensemble indicates a linear dependence of rainfall on global mean temperature with high agreement between the models and independent of the SSP; the multi-model mean for JJAS projects an increase of 0.33 mm/day and 5.3 % per degree of global warming. This is significantly higher than in the CMIP-5 projections. Most models project that the increase will contribute to the precipitation especially in the Himalaya region and to the northeast of the Bay of Bengal, as well as the west coast of India. Interannual variability is found to be increasing in the higher-warming scenarios by almost all models. The CMIP-6 simulations largely confirm the findings from CMIP-5 models, but show an increased robustness across models with reduced uncertainties and updated magnitudes towards a stronger increase in monsoon rainfall.

Anja Katzenberger et al.

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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Anja Katzenberger et al.

Anja Katzenberger et al.


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Short summary
The state-of-the-art global climate models that contributed to the latest Coupled Model Intercomparison Project CMIP-6 show a robust increase in Indian Summer Monsoon rainfall. They furthermore show an increase in the year-to-year variability of this seasonal rainfall that crucially influences the livelihood of more than one billion people in India.