Why Is Climate Sensitivity for Solar Forcing Smaller than for an Equivalent CO2 Forcing?

Kaur, H and Bala, G and Seshadri, AK (2023) Why Is Climate Sensitivity for Solar Forcing Smaller than for an Equivalent CO2 Forcing? In: Journal of Climate, 36 (3). pp. 775-789.

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Abstract

Previous studies have shown that climate sensitivity, defined as the global mean surface temperature change per unit radiative forcing, is smaller for solar radiative forcing compared to an equivalent CO2 radiative forcing. We investigate the causes for this difference using the NCAR CAM4 model. The contributions to the climate feedback parameter, which is inversely related to climate sensitivity, are estimated for water vapor, lapse rate, Planck, albedo, and cloud feedbacks using the radiative kernel technique. The total feedback estimated for CO2 and solar radiative forcing from our model simulations is 21.23 and 21.45 W m22 K21, respectively. We find that the difference in feedback between the two cases is primarily due to differences in lapse rate, water vapor, and cloud feedbacks, which together explain 65% of the difference in total feedback. The rest comes from Planck and albedo feedbacks. The differences in feedbacks arise mainly from differences in the horizontal (meridional) structure of forcing and the consequent warming. Our study provides important insights into the effects of the meridional structure of forcing on climate feedback, which is important for evaluating global climate change from different forcing agents.

Item Type:	Journal Article
Publication:	Journal of Climate
Publisher:	American Meteorological Society
Additional Information:	The copyright for this article belongs to American Meteorological Society.
Keywords:	Atmospheric radiation; Carbon dioxide; Climate change; Solar radiation; Water vapor, Albedo feedbacks; Climate feedbacks; Climate sensitivity; Cloud feedbacks; Forcings; General circulation model; Lapse rate; Radiative fluxes; Radiative forcings; Solar forcing, Climate models
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	21 Feb 2023 03:35
Last Modified:	21 Feb 2023 03:35
URI:	https://eprints.iisc.ac.in/id/eprint/80552

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