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Robust evidence for reversal of the trend in aerosol effective climate forcing

Anthropogenic aerosols exert a cooling influence that offsets part of the greenhouse gas warming.
Due to their short tropospheric lifetime of only several days, the aerosol forcing responds quickly to emissions.
Here, we present and discuss the evolution of the aerosol forcing since 2000. There are multiple lines of evidence
that allow us to robustly conclude that the anthropogenic aerosol effective radiative forcing (ERF) – both aerosol–
radiation interactions (ERFari) and aerosol–cloud interactions (ERFaci) – has become less negative globally, i.e.
the trend in aerosol effective radiative forcing changed sign from negative to positive. Bottom-up inventories
show that anthropogenic primary aerosol and aerosol precursor emissions declined in most regions of the world;
observations related to aerosol burden show declining trends, in particular of the fine-mode particles that make
up most of the anthropogenic aerosols; satellite retrievals of cloud droplet numbers show trends in regions with
aerosol declines that are consistent with these in sign, as do observations of top-of-atmosphere radiation. Climate
model results, including a revised set that is constrained by observations of the ocean heat content evolution show
a consistent sign and magnitude for a positive forcing relative to the year 2000 due to reduced aerosol effects.
This reduction leads to an acceleration of the forcing of climate change, i.e. an increase in forcing by 0.1 to
0.3 W m−2
, up to 12 % of the total climate forcing in 2019 compared to 1750 according to the Intergovernmental
Panel on Climate Change (IPCC).

Identiferoai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:82017
Date08 November 2022
CreatorsQuaas, Johannes, Jia, Hailing, Smith, Chris, Albright, Anna Lea, Aas, Wenche, Bellouin, Nicolas, Boucher, Olivier, Doutriaux-Boucher, Marie, Forster, Piers M., Grosvenor, Daniel, Jenkins, Stuart, Klimont, Zbigniew, Loeb, Norman G., Ma, Xiaoyan, Naik, Vaishali, Paulot, Fabien, Stier, Philip, Wild, Martin, Myhre, Gunnar, Schulz, Michael
PublisherEuropean Geosciences Union, Copernicus Publications
Source SetsHochschulschriftenserver (HSSS) der SLUB Dresden
LanguageEnglish
Detected LanguageEnglish
Typeinfo:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text
Rightsinfo:eu-repo/semantics/openAccess
Relation10.5194/acp-22-12221-2022

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