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Title: Bounding global aerosol radiative forcing of climate change

Abstract

Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This work offers a new range of aerosol radiative forcing over the industrial era based on multiple, traceable and arguable lines of evidence, including modelling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol-radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol-driven increases in liquid cloud droplet number concentration. Yet, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed-phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of -1.60 to -0.65 Wm -2, or -2.0 to -0.4 Wm -2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessmentmore » but shifted towards more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial-era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.« less

Authors:
; ORCiD logo
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); European Research Council (ERC)
OSTI Identifier:
1570661
Report Number(s):
BNL-212193-2019-JAAM
Journal ID: ISSN 8755--1209
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
Reviews of Geophysics
Additional Journal Information:
Journal Name: Reviews of Geophysics; Journal ID: ISSN 8755--1209
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Bellouin, N, and Schwartz, Stephen E. Bounding global aerosol radiative forcing of climate change. United States: N. p., 2019. Web. doi:10.1029/2019RG000660.
Bellouin, N, & Schwartz, Stephen E. Bounding global aerosol radiative forcing of climate change. United States. doi:10.1029/2019RG000660.
Bellouin, N, and Schwartz, Stephen E. Fri . "Bounding global aerosol radiative forcing of climate change". United States. doi:10.1029/2019RG000660.
@article{osti_1570661,
title = {Bounding global aerosol radiative forcing of climate change},
author = {Bellouin, N and Schwartz, Stephen E.},
abstractNote = {Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This work offers a new range of aerosol radiative forcing over the industrial era based on multiple, traceable and arguable lines of evidence, including modelling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol-radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol-driven increases in liquid cloud droplet number concentration. Yet, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed-phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of -1.60 to -0.65 Wm-2, or -2.0 to -0.4 Wm-2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted towards more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial-era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.},
doi = {10.1029/2019RG000660},
journal = {Reviews of Geophysics},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {10}
}

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This content will become publicly available on October 4, 2020
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