EGU2020-3464
https://doi.org/10.5194/egusphere-egu2020-3464
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Interactive stratospheric aerosol model experiments suggest a strong impact of climate change on the aerosol evolution and radiative forcing from future eruptions.

Thomas Aubry1, Anja Schmidt1,2, and Jim Haywood3,4
Thomas Aubry et al.
  • 1Department of Geography, University of Cambridge, Cambridge, UK (thom.aubry@gmail.com)
  • 2Department of Chemistry, University of Cambridge, Cambridge, UK (as2737@cam.ac.uk)
  • 3UK Met Office, Exeter, UK (jim.haywood@metoffice.gov.uk )
  • 4Department of Mathematics, University of Exeter, UK (jim.haywood@metoffice.gov.uk )

Radiative forcing from stratospheric volcanic sulfate aerosols is a key driver of climate variability. However, climate change may also impact volcanic forcing which remains largely unexplored. Atmospheric processes indeed control virtually all mechanisms that govern volcanic forcing, such as the rise of the volcanic column, the chemical and microphysical evolution of volcanic aerosols and their transport in the atmosphere.

Accordingly, we present novel numerical experiments combining chemistry-climate and volcanic plume modelling to investigate how climate change will affect volcanic forcing. We compare the aerosol evolution and radiative forcing following two eruption cases in two different climates (historical 1990’s and SSP5 8.5 2090’s). We chose two tropical eruptions: i) a strong intensity (i.e., mass flux), Pinatubo-like eruption emitting 10 Tg of sulfur dioxide (SO2); and ii) a moderate intensity eruption emitting 1 Tg of SO2, similar to eruptions such as those of Merapi in 2010, Nabro in 2011 or Kelud in 2014, which have had major impacts on the stratospheric aerosol background and are thought to have contributed to the global temperature hiatus in the early 21st century. The chemistry-climate model that we use (UM_UKCA version 11.2) has the capacity to interactively simulate the chemical and microphysical evolution of stratospheric sulfate aerosol given an initial injection of SO2. Furthermore, we use a plume model to calculate SO2 injection heights for a given eruption intensity and atmospheric conditions simulated by UM-UKCA.

In our experiments, the peak stratospheric aerosol optical depth (SAOD) of the high-intensity, Pinatubo-like eruption increases by 10% in the SSP5 8.5 2090 climate compared to the historical 1990 climate. Furthermore, the peak global-mean top-of-the-atmosphere radiative forcing of the same eruption increases by 30%. In contrast, the peak SAOD of the moderate intensity eruption decreases by a factor of 4 (with radiative forcing being small compared to simulated natural variability). Our results thus suggest that volcanic forcing will become more extreme and polarized in the future, with the forcing associated with moderate-intensity and relatively frequent eruptions being muted, but the forcing associated with high-intensity and relatively rare eruptions being amplified. We analyze which mechanisms are responsible for the simulated impacts of climate change on volcanic forcing, and discuss potential additional feedbacks expected in our future ocean-atmosphere coupled simulations.

How to cite: Aubry, T., Schmidt, A., and Haywood, J.: Interactive stratospheric aerosol model experiments suggest a strong impact of climate change on the aerosol evolution and radiative forcing from future eruptions., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3464, https://doi.org/10.5194/egusphere-egu2020-3464, 2020

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Presentation version 3 – uploaded on 05 May 2020
Minor text changes in conclusion slide
  • CC1: Comment on EGU2020-3464, Carley Iles, 06 May 2020

    I thought this was a very nice and clear presentation. Also interesting findings! I had not considered the idea that climate change could change the volcanic radiative forcing itself before.

    • AC1: Reply to CC1, Thomas Aubry, 17 May 2020

      Dear Carley,

      I apologize for the late answer and sincerely thank you for taking the time to share your encouraging feedbacks, they are much appreciated! Please don't hesitate to be in touch (ta460@cam.ac.uk) if you have any question.

      Thanks!

      Thomas

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