South Asian Summer Monsoon under Stratospheric Aerosol Intervention

[Geoengineering News]

https://www.researchsquare.com/article/rs-4631758/v1

Authors 

Simone Tilmes, Asutosh Acharya, Ewa Bednarz, Suvarna Fadnavis

26 August 2024

https://doi.org/10.21203/rs.3.rs-4631758/v1

Abstract

The South Asian summer monsoon (SAM) bears significant importance for agriculture, water resources, economy, and environmental aspects of the region for more than 1.5 billion people. To minimize the adverse impacts of global warming, Stratospheric Aerosol Intervention (SAI) has been proposed to lower surface temperatures by reflecting a portion of solar radiation back into space. However, the effects of SAI on SAM are still very uncertain and demand more research. We investigate this using the Stratospheric Aerosol Geoengineering Large Ensemble datasets. Our study reveals a reduction in the mean and extreme summer monsoon precipitation under SAI in this scenario, driven by a combination of the SAI-induced lower stratospheric warming and the associated weakening of the northern hemispheric subtropical jet, changes in the upper-tropospheric wave activities, geopotential height anomalies, and the strength of the Asian Summer Monsoon Anticyclone. Local dust changes that can otherwise be important for SAM rainfall variability under climate change also contribute to changes under SAI. As the interest in SAI research grows, our results demonstrate the urgent need to understand SAM variability under different SAI scenarios, which is essential for sustainable development and disaster preparedness in South Asia.

Source: Research Square

[Michael MacCracken]

It would sure be helpful if they made clear what they were using as the reference. Is the monsoon less than it would be without SRM as GHGs go up, or is it less than it was in preindustrial times?

Mike MacCracken

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[Simone Tilmes]

HI Mike, 

The reference is present-day, not pre-industrial, and yes, the monsoonal precipitation would be less than in present-day if SAI were applied to a high GHG scenario in the future.

This study explores the processes that can lead to rainfall changes for monsoon precipitation over India, demonstrated on one specific model simulation. 

Simone

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Simone Tilmes,
Atmospheric  Chemistry, Observations & Modeling Lab
National Center for Atmospheric Research
PO Box 3000
Boulder, Colorado  80307-3000
303-497-1445
303-497-1400 (fax)
til...@ucar.edu