EGU23-1699, updated on 24 Apr 2023
https://doi.org/10.5194/egusphere-egu23-1699
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Assessing effective radiative forcing from aerosol-cloud interactions over the global ocean

Casey Wall1,2, Joel Norris2, Anna Possner3, Daniel McCoy4, Isabel McCoy5,6, and Nicholas Lutsko2
Casey Wall et al.
  • 1University of Oslo, Geosciences, Norway (cawa@geo.uio.no)
  • 2Scripps Institution of Oceanography, University of California San Diego, USA
  • 3Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Germany
  • 4University of Wyoming, Department of Atmospheric Sciences, USA
  • 5Rosenstiel School of Marine and Atmospheric Science, University of Miami, USA
  • 6Cooperative Programs for the Advancement of Earth System Science, University Corporation for Atmospheric Research, USA

How clouds respond to anthropogenic sulfate aerosols is one of the largest sources of uncertainty in the radiative forcing of climate over the industrial era. This uncertainty limits our ability to predict equilibrium climate sensitivity (ECS) – the equilibrium global warming following a doubling of atmospheric CO2. Here we use satellite observations to quantify relationships between sulfate aerosols and low-level clouds while carefully controlling for meteorology. We then combine the relationships with estimates of the change in sulfate concentration since about 1850 to constrain the associated radiative forcing. We estimate that the cloud-mediated radiative forcing from anthropogenic sulfate aerosols is −1.11 ± 0.43 W m-2 over the global ocean (95% confidence). This constraint implies that ECS is likely between 2.9 and 4.5 K (66% confidence). Our results indicate that aerosol forcing is less uncertain and ECS is probably larger than the ranges proposed by recent climate assessments.

How to cite: Wall, C., Norris, J., Possner, A., McCoy, D., McCoy, I., and Lutsko, N.: Assessing effective radiative forcing from aerosol-cloud interactions over the global ocean, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1699, https://doi.org/10.5194/egusphere-egu23-1699, 2023.