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Forcings and feedbacks in the GeoMIP ensemble for a reduction in solar irradiance and increase in CO 2
Author(s) -
Huneeus Nicolas,
Boucher Olivier,
Alterskjær Kari,
Cole Jason N. S.,
Curry Charles L.,
Ji Duoying,
Jones Andy,
Kravitz Ben,
Kristjánsson Jón Egill,
Moore John C.,
Muri Helene,
Niemeier Ulrike,
Rasch Phil,
Robock Alan,
Singh Balwinder,
Schmidt Hauke,
Schulz Michael,
Tilmes Simone,
Watanabe Shingo,
Yoon JinHo
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd021110
Subject(s) - shortwave , environmental science , cloud forcing , radiative forcing , forcing (mathematics) , irradiance , solar irradiance , atmospheric sciences , context (archaeology) , longwave , radiative transfer , energy budget , shortwave radiation , cloud cover , atmosphere (unit) , climate model , climatology , climate change , meteorology , cloud computing , radiation , physics , geography , computer science , ecology , aerosol , archaeology , quantum mechanics , biology , geology , thermodynamics , operating system
The effective radiative forcings (including rapid adjustments) and feedbacks associated with an instantaneous quadrupling of the preindustrial CO 2 concentration and a counterbalancing reduction of the solar constant are investigated in the context of the Geoengineering Model Intercomparison Project (GeoMIP). The forcing and feedback parameters of the net energy flux, as well as its different components at the top‐of‐atmosphere (TOA) and surface, were examined in 10 Earth System Models to better understand the impact of solar radiation management on the energy budget. In spite of their very different nature, the feedback parameter and its components at the TOA and surface are almost identical for the two forcing mechanisms, not only in the global mean but also in their geographical distributions. This conclusion holds for each of the individual models despite intermodel differences in how feedbacks affect the energy budget. This indicates that the climate sensitivity parameter is independent of the forcing (when measured as an effective radiative forcing). We also show the existence of a large contribution of the cloudy‐sky component to the shortwave effective radiative forcing at the TOA suggesting rapid cloud adjustments to a change in solar irradiance. In addition, the models present significant diversity in the spatial distribution of the shortwave feedback parameter in cloudy regions, indicating persistent uncertainties in cloud feedback mechanisms.