G6-1.5K-SAI and G6sulfur: changes in impacts and uncertainty depending on stratospheric aerosol injection strategy in the Geoengineering Model Intercomparison Project
10 affiliations
- 1NSF National Center for Atmospheric Research (Boulder, United States of America)
- 2Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
- 3Sandia National Laboratories, Albuquerque, NM, USA
- 4Atmospheric, Climate, and Earth Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
- 5Department of Earth and Atmospheric Sciences, Indiana University Bloomington, Bloomington, IN, USA
- 6Advanced Institute for Marine Ecosystem Change (WPI-AIMEC), Tohoku University, Sendai, Japan
- 7Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Kanagawa, Japan
- 8Department of Mathematics and Statistics, University of Exeter, Exeter, UK
- 9Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO, USA
- 10National Oceanographic and Atmospheric Administration Chemical Sciences Laboratory (NOAA CSL), Boulder, CO, USA
Abstract
We report initial results for G6-1.5K-SAI, a climate model experiment proposed by the Geoengineering Model Intercomparison Project (GeoMIP). G6-1.5K-SAI, which simulates a stratospheric aerosol injection (SAI) to limit global warming to ∼ 1.5 °C above preindustrial in each model, features several design updates relative to previous GeoMIP experiment G6sulfur, such as hemispherically symmetric subtropical injection (30° N and 30° S) instead of equatorial injection. Due to differences in climate sensitivity, models disagree on the amount of warming to be offset, and therefore on the total injection required. While they agree strongly on the rate of cooling per unit rate of injection (∼ 0.1 °C per Tg SO2 yr−1, a similar value to G6sulfur models with interactive SO2), similarities in aerosol representation and disagreements in aerosol optical depth (AOD) per rate of unit injection and in rate of cooling per unit AOD mean this agreement may not imply accuracy. In all participating models, SAI cools the land surface more than the ocean and offsets mid- and high-latitude precipitation increases under global warming, but models disagree on the magnitude of residual Arctic amplification and changes to tropical precipitation. Relative to G6sulfur, G6-1.5K-SAI cools the Arctic more strongly, and also decreases precipitation less, especially in the tropics and over land. All in all, while the new G6-1.5K-SAI experiment constitutes an update over the older G6sulfur, due to the differences in scenario across these two experiments, any differences in SAI impacts must be evaluated carefully.
Related
- Resilient Stratospheric Aerosol Injection is Cooperative
- Uptake of Stratospheric Species on Minerals Proposed for Stratospheric Aerosol Injection
- Mapping justice claims for solar geoengineering
- Optimizing Geoengineering Interventions Using Differentiable Climate Models
- Intercomparison of Four Stomatal Flux-Based Ozone Damage Schemes in CLM5.0 over China: Implications for Carbon, Water, and Energy Fluxes
BibTeX
@article{lee2026g615ksai,
title = {{G6-1.5K-SAI and G6sulfur: changes in impacts and uncertainty depending on stratospheric aerosol injection strategy in the Geoengineering Model Intercomparison Project}},
author = {Walker Lee and Daniele Visioni and Benjamin Wagman and Christopher Robert Wentland and Ben Kravitz and Shingo Watanabe and Takashi Sekiya and Andy Jones and Jim Haywood and Matthew Henry and Ewa Bednarz},
journal = {Atmospheric chemistry and physics},
year = {2026},
month = may,
doi = {10.5194/acp-26-7463-2026},
url = {https://doi.org/10.5194/acp-26-7463-2026},
note = {CC BY},
}
RIS
TY - JOUR
TI - G6-1.5K-SAI and G6sulfur: changes in impacts and uncertainty depending on stratospheric aerosol injection strategy in the Geoengineering Model Intercomparison Project
AU - Walker Lee
AU - Daniele Visioni
AU - Benjamin Wagman
AU - Christopher Robert Wentland
AU - Ben Kravitz
AU - Shingo Watanabe
AU - Takashi Sekiya
AU - Andy Jones
AU - Jim Haywood
AU - Matthew Henry
AU - Ewa Bednarz
PY - 2026
DA - 2026/05/29
JO - Atmospheric chemistry and physics
DO - 10.5194/acp-26-7463-2026
UR - https://doi.org/10.5194/acp-26-7463-2026
AB - We report initial results for G6-1.5K-SAI, a climate model experiment proposed by the Geoengineering Model Intercomparison Project (GeoMIP). G6-1.5K-SAI, which simulates a stratospheric aerosol injection (SAI) to limit global warming to ∼ 1.5 °C above preindustrial in each model, features several design updates relative to previous GeoMIP experiment G6sulfur, such as hemispherically symmetric subtropical injection (30° N and 30° S) instead of equatorial injection. Due to differences in climate sensitivity, models disagree on the amount of warming to be offset, and therefore on the total injection required. While they agree strongly on the rate of cooling per unit rate of injection (∼ 0.1 °C per Tg SO2 yr−1, a similar value to G6sulfur models with interactive SO2), similarities in aerosol representation and disagreements in aerosol optical depth (AOD) per rate of unit injection and in rate of cooling per unit AOD mean this agreement may not imply accuracy. In all participating models, SAI cools the land surface more than the ocean and offsets mid- and high-latitude precipitation increases under global warming, but models disagree on the magnitude of residual Arctic amplification and changes to tropical precipitation. Relative to G6sulfur, G6-1.5K-SAI cools the Arctic more strongly, and also decreases precipitation less, especially in the tropics and over land. All in all, while the new G6-1.5K-SAI experiment constitutes an update over the older G6sulfur, due to the differences in scenario across these two experiments, any differences in SAI impacts must be evaluated carefully.
SN - 1680-7316
SN - 1680-7324
ER -