27 Aug 2021

27 Aug 2021

Review status: this preprint is currently under review for the journal ESD.

How large is the design space for stratospheric aerosol geoengineering?

Yan Zhang1, Douglas G. MacMartin1, Daniele Visioni1, and Ben Kravitz2,3 Yan Zhang et al.
  • 1Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
  • 2Department of Earth and Atmospheric Science, Indiana University, Bloomington, IN, USA
  • 3Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA

Abstract. Stratospheric aerosol injection (SAI), as a possible supplement to emission reduction, has the potential to reduce some of the risks associated with climate change. Adding aerosols to the lower stratosphere results in global cooling. However, different choices for the aerosol injection latitude(s) and season(s) have been shown to lead to significant differences in regional surface climate, introducing a design aspect to SAI. Past research has shown that there are at least three independent degrees of freedom (DOF) that can be used to simultaneously manage three different climate goals. Knowing how many more DOFs there are, and thus how many independent climate goals can be simultaneously managed, is essential to understanding fundamental limits of how well SAI might compensate for anthropogenic climate change, and evaluating any underlying trade-offs between different climate goals. Here we quantify the number of meaningfully-independent DOFs of the SAI design space. This number of meaningfully-independent DOFs depends on both the amount of cooling and the climate variables used for quantifying the changes in surface climate. At low levels of global cooling, only a small set of injection choices yield detectably different surface climate responses. For a cooling level of 1–1.5 °C, we find that there are likely between 6 and 8 meaningfully-independent DOFs. This narrows down the range of available DOF and also reveals new opportunities for exploring alternate SAI designs with different distributions of climate impacts.

Yan Zhang et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on Zhang et al', Anonymous Referee #1, 27 Sep 2021
  • RC2: 'Comment on esd-2021-70', Anonymous Referee #2, 13 Oct 2021

Yan Zhang et al.

Data sets

Data from: How large is the design space for stratospheric aerosol geoengineering? Yan Zhang, Douglas G. MacMartin, Daniele Visioni, Ben Kravitz

Yan Zhang et al.


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Short summary
Adding SO2 to the stratosphere could temporarily cool the planet by reflecting more sunlight back to the space. However, adding SO2 at different latitude(s) and season(s) lead to significant differences in regional surface climate. This study shows that, to cool the planet by 1–1.5 °C, there are likely 6-8 choices of injection latitude(s) and season(s) that lead to meaningfully different distributions of climate impacts.