CMIP5 Climate Models Overestimate Cooling by Volcanic Aerosols

Abstract We compare projections of the observed hemispherical mean surface temperature (HadCRUT4.6.0.0) and the ensemble mean of CMIP5 climate models' simulations on a set of standard regression model forcing variables. We find that the volcanic aerosol regression coefficients of the CMIP5 simu...

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Bibliographic Details
Main Authors: Petr Chylek, Chris Folland, James D. Klett, Manvendra K. Dubey
Format: Article
Language:English
Published: Wiley 2020-02-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1029/2020GL087047
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Summary:Abstract We compare projections of the observed hemispherical mean surface temperature (HadCRUT4.6.0.0) and the ensemble mean of CMIP5 climate models' simulations on a set of standard regression model forcing variables. We find that the volcanic aerosol regression coefficients of the CMIP5 simulations are consistently significantly larger (by 40–49%) than the volcanic aerosol coefficients of the observed temperature. The probability that the observed differences are caused just by chance is much less than 0.01. The overestimate is due to the climate models' response to volcanic aerosol radiative forcing. The largest overestimate occurs in the winter season of each hemisphere. We hypothesize that the models' parameterization of aerosol‐cloud interactions within ice and mixed phase clouds is a likely source of this discrepancy. Furthermore, the models significantly underestimate the effect of solar variability on temperature for both hemispheres.
ISSN:0094-8276
1944-8007