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Causes of the reduction in uncertainty in the anthropogenic radiative forcing of climate between IPCC (2001) and IPCC (2007)
Author(s) -
Haywood Jim,
Schulz Michael
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl030749
Subject(s) - radiative forcing , environmental science , greenhouse gas , radiative transfer , forcing (mathematics) , atmospheric sciences , climatology , cloud forcing , climate change , albedo (alchemy) , climate model , aerosol , meteorology , geography , physics , ecology , art , quantum mechanics , geology , performance art , biology , art history
Mechanisms that drive climate change are quantified by the radiative forcing which is the perturbation to the global energy balance of the Earth/atmosphere system. These mechanisms may be of anthropogenic or natural origins and each has an associated level of scientific uncertainty. Until recently, even the sign of the anthropogenic radiative forcing has been in doubt because strong, poorly quantified negative radiative forcings such as those from aerosols act to oppose the strong, well quantified positive radiative forcings from well mixed greenhouse gases. We present an analysis of the probability distribution function of the anthropogenic radiative forcing for the individual forcing mechanisms identified by IPCC (2001) and IPCC (2007). We conclude that significant progress in reducing the uncertainty of the anthropogenic radiative forcing has been made since IPCC (2001). The single most important contributor to this conclusion appears to be the reduction in the uncertainty associated with the aerosol direct effect, followed by the provision of a best estimate for the aerosol cloud albedo indirect effect.