Sensitivity of Historical Climate Simulations to Uncertain Aerosol Forcing

Andrea J. Dittus; Ed Hawkins; Laura J. Wilcox; Rowan T. Sutton; Christopher J. Smith; Martin B. Andrews; Piers M. Forster

doi:10.1029/2019GL085806

Sensitivity of Historical Climate Simulations to Uncertain Aerosol Forcing

Andrea J. Dittus, Ed Hawkins, Laura J. Wilcox, Rowan T. Sutton, Christopher J. Smith, Martin B. Andrews, Piers M. Forster

Department of Water and Climate

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36 Citations (Scopus)

Abstract

The relative importance of anthropogenic aerosol in decadal variations of historical climate is uncertain, largely due to uncertainty in aerosol radiative forcing. We analyze a novel large ensemble of simulations with HadGEM3-GC3.1 for 1850–2014, where anthropogenic aerosol and precursor emissions are scaled to sample a wide range of historical aerosol radiative forcing with present-day values ranging from –0.38 to –1.50 Wm–2. Five ensemble members are run for each of five aerosol scaling factors. Decadal variations in surface temperatures are strongly sensitive to aerosol forcing, particularly between 1950 and 1980. Post-1980, trends are dominated by greenhouse gas forcing, with much lower sensitivity to aerosol emission differences. Most realizations with aerosol forcing more negative than about –1 Wm–2 simulate stronger cooling trends in the mid-20th century compared with observations, while the simulated warming post-1980 always exceeds observed warming, likelydue to a warm bias in the transient climate response in HadGEM3-GC3.1.

Original language	English
Article number	e2019GL085806
Number of pages	10
Journal	Geophysical Research Letters
Volume	47
Issue number	13
DOIs	https://doi.org/10.1029/2019GL085806
Publication status	Published - 16 Jul 2020

Bibliographical note

Funding Information:
The SMURPHS ensemble was funded by the Natural Environment Research Council (grants NE/N006054/1 and NE/N006038/1) and supported by the National Centre for Atmospheric Science. We acknowledge use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. In addition to the data from this manuscript being available at https://gws‐access.ceda.ac.uk/public/smurphs/SMURPHS/ , this data set is part of an ongoing, larger deposit at https://catalogue.ceda.ac.uk/uuid/5808b237bdb5485d9bc3595f39ce85e3 . We thank Prof. Chris Forest and an anonymous reviewer for their constructive evaluation of the manuscript.

Funding Information:
The SMURPHS ensemble was funded by the Natural Environment Research Council (grants NE/N006054/1 and NE/N006038/1) and supported by the National Centre for Atmospheric Science. We acknowledge use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. In addition to the data from this manuscript being available at https://gws-access.ceda.ac.uk/public/smurphs/SMURPHS/, this data set is part of an ongoing, larger deposit at https://catalogue.ceda.ac.uk/uuid/5808b237bdb5485d9bc3595f39ce85e3. We thank Prof. Chris Forest and an anonymous reviewer for their constructive evaluation of the manuscript.

Publisher Copyright:
©2020. The Authors.

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@article{81b6789bb64a4e31a99638da59eca936,

title = "Sensitivity of Historical Climate Simulations to Uncertain Aerosol Forcing",

abstract = "The relative importance of anthropogenic aerosol in decadal variations of historical climate is uncertain, largely due to uncertainty in aerosol radiative forcing. We analyze a novel large ensemble of simulations with HadGEM3-GC3.1 for 1850–2014, where anthropogenic aerosol and precursor emissions are scaled to sample a wide range of historical aerosol radiative forcing with present-day values ranging from –0.38 to –1.50 Wm–2. Five ensemble members are run for each of five aerosol scaling factors. Decadal variations in surface temperatures are strongly sensitive to aerosol forcing, particularly between 1950 and 1980. Post-1980, trends are dominated by greenhouse gas forcing, with much lower sensitivity to aerosol emission differences. Most realizations with aerosol forcing more negative than about –1 Wm–2 simulate stronger cooling trends in the mid-20th century compared with observations, while the simulated warming post-1980 always exceeds observed warming, likelydue to a warm bias in the transient climate response in HadGEM3-GC3.1.",

author = "Dittus, {Andrea J.} and Ed Hawkins and Wilcox, {Laura J.} and Sutton, {Rowan T.} and Smith, {Christopher J.} and Andrews, {Martin B.} and Forster, {Piers M.}",

note = "Funding Information: The SMURPHS ensemble was funded by the Natural Environment Research Council (grants NE/N006054/1 and NE/N006038/1) and supported by the National Centre for Atmospheric Science. We acknowledge use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. In addition to the data from this manuscript being available at https://gws‐access.ceda.ac.uk/public/smurphs/SMURPHS/ , this data set is part of an ongoing, larger deposit at https://catalogue.ceda.ac.uk/uuid/5808b237bdb5485d9bc3595f39ce85e3 . We thank Prof. Chris Forest and an anonymous reviewer for their constructive evaluation of the manuscript. Funding Information: The SMURPHS ensemble was funded by the Natural Environment Research Council (grants NE/N006054/1 and NE/N006038/1) and supported by the National Centre for Atmospheric Science. We acknowledge use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. In addition to the data from this manuscript being available at https://gws-access.ceda.ac.uk/public/smurphs/SMURPHS/, this data set is part of an ongoing, larger deposit at https://catalogue.ceda.ac.uk/uuid/5808b237bdb5485d9bc3595f39ce85e3. We thank Prof. Chris Forest and an anonymous reviewer for their constructive evaluation of the manuscript. Publisher Copyright: {\textcopyright}2020. The Authors.",

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doi = "10.1029/2019GL085806",

language = "English",

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AU - Dittus, Andrea J.

AU - Hawkins, Ed

AU - Wilcox, Laura J.

AU - Sutton, Rowan T.

AU - Smith, Christopher J.

AU - Andrews, Martin B.

AU - Forster, Piers M.

N1 - Funding Information: The SMURPHS ensemble was funded by the Natural Environment Research Council (grants NE/N006054/1 and NE/N006038/1) and supported by the National Centre for Atmospheric Science. We acknowledge use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. In addition to the data from this manuscript being available at https://gws‐access.ceda.ac.uk/public/smurphs/SMURPHS/ , this data set is part of an ongoing, larger deposit at https://catalogue.ceda.ac.uk/uuid/5808b237bdb5485d9bc3595f39ce85e3 . We thank Prof. Chris Forest and an anonymous reviewer for their constructive evaluation of the manuscript. Funding Information: The SMURPHS ensemble was funded by the Natural Environment Research Council (grants NE/N006054/1 and NE/N006038/1) and supported by the National Centre for Atmospheric Science. We acknowledge use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. In addition to the data from this manuscript being available at https://gws-access.ceda.ac.uk/public/smurphs/SMURPHS/, this data set is part of an ongoing, larger deposit at https://catalogue.ceda.ac.uk/uuid/5808b237bdb5485d9bc3595f39ce85e3. We thank Prof. Chris Forest and an anonymous reviewer for their constructive evaluation of the manuscript. Publisher Copyright: ©2020. The Authors.

PY - 2020/7/16

Y1 - 2020/7/16

N2 - The relative importance of anthropogenic aerosol in decadal variations of historical climate is uncertain, largely due to uncertainty in aerosol radiative forcing. We analyze a novel large ensemble of simulations with HadGEM3-GC3.1 for 1850–2014, where anthropogenic aerosol and precursor emissions are scaled to sample a wide range of historical aerosol radiative forcing with present-day values ranging from –0.38 to –1.50 Wm–2. Five ensemble members are run for each of five aerosol scaling factors. Decadal variations in surface temperatures are strongly sensitive to aerosol forcing, particularly between 1950 and 1980. Post-1980, trends are dominated by greenhouse gas forcing, with much lower sensitivity to aerosol emission differences. Most realizations with aerosol forcing more negative than about –1 Wm–2 simulate stronger cooling trends in the mid-20th century compared with observations, while the simulated warming post-1980 always exceeds observed warming, likelydue to a warm bias in the transient climate response in HadGEM3-GC3.1.

AB - The relative importance of anthropogenic aerosol in decadal variations of historical climate is uncertain, largely due to uncertainty in aerosol radiative forcing. We analyze a novel large ensemble of simulations with HadGEM3-GC3.1 for 1850–2014, where anthropogenic aerosol and precursor emissions are scaled to sample a wide range of historical aerosol radiative forcing with present-day values ranging from –0.38 to –1.50 Wm–2. Five ensemble members are run for each of five aerosol scaling factors. Decadal variations in surface temperatures are strongly sensitive to aerosol forcing, particularly between 1950 and 1980. Post-1980, trends are dominated by greenhouse gas forcing, with much lower sensitivity to aerosol emission differences. Most realizations with aerosol forcing more negative than about –1 Wm–2 simulate stronger cooling trends in the mid-20th century compared with observations, while the simulated warming post-1980 always exceeds observed warming, likelydue to a warm bias in the transient climate response in HadGEM3-GC3.1.

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U2 - 10.1029/2019GL085806

DO - 10.1029/2019GL085806

M3 - Article

SN - 0094-8276

VL - 47

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 13

M1 - e2019GL085806

ER -

Sensitivity of Historical Climate Simulations to Uncertain Aerosol Forcing

Abstract

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