Cited by 20Climate variability and modelsAtmospheric aerosols and cloudsMeteorological Phenomena and Simulations

Quantifying uncertainty from aerosol and atmospheric parameters and their impact on climate sensitivity

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Fletcher, Christopher G., Kravitz, Ben, Badawy, Bakr·2018·Atmospheric Chemistry and Physics

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Abstract

Climate sensitivity in Earth system models (ESMs) is an emergent property that is affected by structural (missing or inaccurate model physics) and parametric (variations in model parameters) uncertainty. This work provides the first quantitative assessment of the role of compensation between uncertainties in aerosol forcing and atmospheric parameters, and their impact on the climate sensitivity of the Community Atmosphere Model, Version 4 (CAM4). Running the model with prescribed ocean and ice conditions, we perturb four parameters related to sulfate and black carbon aerosol radiative forcing and distribution, as well as five atmospheric parameters related to clouds, convection, and radiative flux. In this experimental setup where aerosols do not affect the properties of clouds, the atmospheric parameters explain the majority of variance in climate sensitivity, with two parameters being the most important: one controlling low cloud amount, and one controlling the timescale for deep convection. Although the aerosol parameters strongly affect aerosol optical depth, their impacts on climate sensitivity are substantially weaker than the impacts of the atmospheric parameters, but this result may depend on whether aerosol–cloud interactions are simulated. Based on comparisons to inter-model spread of other ESMs, we conclude that structural uncertainties in this configuration of CAM4 likely contribute 3 times more to uncertainty in climate sensitivity than parametric uncertainties. We provide several parameter sets that could provide plausible (measured by a skill score) configurations of CAM4, but with different sulfate aerosol radiative forcing, black carbon radiative forcing, and climate sensitivity.

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Crossref · 10.5194/acp-18-17529-2018

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  • [247] use Gaussian processes to emulate climate model outputs based on nine possible aerosol parameter settings, allowing them to establish plausible parameter ranges with only 350 climate model runs instead of >100,000.

    “As a recent example, [247] use Gaussian processes to emulate climate model outputs based on nine possible aerosol parameter settings, allowing them to establish plausible parameter ranges (and thus much better calibrated error-bars) with only 350 climate model runs instead of >100,000.”

    From Tackling climate change with machine learning (2023) · cites this paper as [247]

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Authors
Fletcher, C. G., Kravitz, B., & Badawy, B.
Affiliations
  • University of Waterloo (CA)
  • Pacific Northwest National Laboratory (US)
  • Environment and Climate Change Canada (CA)
Corresponding author
  • Fletcher, Christopher G.
  • Kravitz, Ben
  • Badawy, Bakr
Venue
Atmospheric Chemistry and Physics
Published
2018-12-11
Volume
18
Issue
23
Pages
17529-17543
ISSN
  • 1680-7316 (ISSN-L)
  • 1680-7324
OpenAlex
W2888391110
Cited by
20
References
45
Citations by year
2026: 4 · 2025: 3 · 2024: 2 · 2023: 3 · 2022: 3 · 2020: 2 · 2019: 2 · 2018: 1
FWCI
0.73
Type
journal article
Language
en
Open access
Locations
  • Atmospheric chemistry and physics (publishedVersion, cc-by)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Biogeosciences (European Geosciences Union) (submittedVersion, cc-by)
Funders
Natural Sciences and Engineering Research Council of Canada (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments)
Topics
  • Physical Sciences › Environmental Science › Global and Planetary Change › Climate variability and models
  • Physical Sciences › Environmental Science › Global and Planetary Change › Atmospheric aerosols and clouds
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Meteorological Phenomena and Simulations
Keywords
climate sensitivity, uncertainty quantification, aerosol radiative forcing, sulfate aerosols, black carbon, aerosol-cloud interactions, structural uncertainty, low cloud fraction, Earth system models, inter-model spread

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