Preprints
https://doi.org/10.5194/egusphere-2022-779
https://doi.org/10.5194/egusphere-2022-779
 
31 Aug 2022
31 Aug 2022

Scenario and Model Dependence of Strategic Solar Climate Intervention in CESM

John T. Fasullo and Jadwiga H. Richter John T. Fasullo and Jadwiga H. Richter
  • National Center for Atmospheric Research, Boulder, CO, 80301, USA

Abstract. Model dependence in simulated responses to stratospheric aerosol injection (SAI) is a major uncertainty surrounding the potential implementation of this solar climate intervention strategy. We identify large differences in the aerosol mass latitudinal distributions between two recently produced climate model SAI large ensembles, despite using similar climate targets and controller algorithms, with the goal of understanding the drivers of such differences. Using a hierarchy of recently produced simulations, we identify three main contributors including: 1) the rapid adjustment of clouds and rainfall to elevated levels of carbon dioxide, 2) the associated low-frequency dynamical responses in the Atlantic Meridional Overturning Circulation, and 3) the contrasts in future climate forcing scenarios. Each uncertainty is unlikely to be significantly narrowed over the likely timeframe of a potential SAI deployment if a 1.5 C target is to be met. The results thus suggest the need for significant flexibility in climate intervention deployment to account for these large uncertainties in the climate system response.

Journal article(s) based on this preprint

05 Jan 2023
| Highlight paper
Dependence of strategic solar climate intervention on background scenario and model physics
John T. Fasullo and Jadwiga H. Richter
Atmos. Chem. Phys., 23, 163–182, https://doi.org/10.5194/acp-23-163-2023,https://doi.org/10.5194/acp-23-163-2023, 2023
Short summary

John T. Fasullo and Jadwiga H. Richter

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-779', Alan Robock, 07 Sep 2022
    • AC1: 'Reply on RC1', John Fasullo, 09 Nov 2022
  • RC2: 'Comment on egusphere-2022-779', Douglas MacMartin, 14 Sep 2022
    • AC2: 'Reply on RC2', John Fasullo, 09 Nov 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-779', Alan Robock, 07 Sep 2022
    • AC1: 'Reply on RC1', John Fasullo, 09 Nov 2022
  • RC2: 'Comment on egusphere-2022-779', Douglas MacMartin, 14 Sep 2022
    • AC2: 'Reply on RC2', John Fasullo, 09 Nov 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision
AR by John Fasullo on behalf of the Authors (09 Nov 2022)  Author's response    Author's tracked changes    Manuscript
ED: Publish as is (22 Nov 2022) by Susannah Burrows

Journal article(s) based on this preprint

05 Jan 2023
| Highlight paper
Dependence of strategic solar climate intervention on background scenario and model physics
John T. Fasullo and Jadwiga H. Richter
Atmos. Chem. Phys., 23, 163–182, https://doi.org/10.5194/acp-23-163-2023,https://doi.org/10.5194/acp-23-163-2023, 2023
Short summary

John T. Fasullo and Jadwiga H. Richter

John T. Fasullo and Jadwiga H. Richter

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Stratospheric aerosol injection (SAI) is often discussed in the media and in policy circles as a possible action to limit future increase in global temperatures. Indeed it has been demonstrated in model simulations that in principle injection could be 'controlled', using model information, to meet specific targets on the temperature increase and its spatial distribution. This paper shows that the simulated climate response to SAI is strongly model-dependent, reflecting fundamental uncertainties in model representation of key processes. In particular this means that the SAI determined by the control algorithms as those required to achieve temperature targets different significantly from one model to another. Specific mechanisms, in particular the difference in rapid response in clouds and in precipitation to an imposed radiative perturbation and the ensuing ocean circulation response, are identified that contribute to the strong differences in model response to SAI. There is also a strong sensitivity to the pre-existing sulphate distribution which will be determined by future anthropogenic emissions. The authors note that these inter-model differences are unlikely to be resolved quickly and that controlled SAI, to achieve specific temperature goals and with well-quantified risks of unexpected consequences, is likely to remain out of reach for many years.
Short summary
The continued high levels of anthropogenic greenhouse gas emissions increase the likelihood that key climate warming thresholds will be exceeded in the coming decades. Here we examine a recently proposed geoengineering approach using two recently produced climate model experiments. We find the associated latitudinal distribution of aerosol mass to exhibit substantial uncertainty suggesting the need for significant flexibility in the location and amount of aerosol delivery if implemented.