Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering

Journal Article · 18 July 2018 · Atmospheric Chemistry and Physics (Online)

DOI: https://doi.org/10.5194/acp-18-10133-2018 · OSTI ID:1556906

Ji, Duoying ^[1]; Fang, Songsong ^[1]; Curry, Charles L. ^[2]; Kashimura, Hiroki ^[3]; Watanabe, Shingo ^[4]; Cole, Jason N. S.  ^[5]; Lenton, Andrew ^[6]; Muri, Helene  ^[7]; Kravitz, Benjamin S.  ^[8]; Moore, John C. ^[9]

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1. Beijing Normal Univ. (China)
2. Univ. of Victoria, BC (Canada)
3. Kobe Univ. (Japan)
4. Japan Agency for Marine-Earth Science and Technology, Yokohama (Japan)
5. Canadian Centre for Climate Modelling and Analysis, Victoria, BC (Canada)
6. Oceans and Atmosphere, Hobart, Tasmania (Australia)
7. Univ. of Oslo (Norway); Norwegian Univ. of Science and Technology, Trondheim (Norway)
8. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
9. Beijing Normal Univ. (China); Univ. of Lapland, Rovaniemi (Finland); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing (China)

We examine extreme temperature and precipitation under two potential geoengineering methods forming part of the Geoengineering Model Intercomparison Project (GeoMIP). The solar dimming experiment G1 is designed to completely offset the global mean radiative forcing due to a CO₂-quadrupling experiment (abrupt4 × CO2), while in GeoMIP experiment G4, the radiative forcing due to the representative concentration pathway 4.5 (RCP4.5) scenario is partly offset by a simulated layer of aerosols in the stratosphere. Both G1 and G4 geoengineering simulations lead to lower minimum temperatures (TNn) at higher latitudes and on land, primarily through feedback effects involving high-latitude processes such as snow cover, sea ice and soil moisture. There is larger cooling of TNn and maximum temperatures (TXx) over land compared with oceans, and the land–sea cooling contrast is larger for TXx than TNn. Maximum 5-day precipitation (Rx5day) increases over subtropical oceans, whereas warm spells (WSDI) decrease markedly in the tropics, and the number of consecutive dry days (CDDs) decreases in most deserts. The precipitation during the tropical cyclone (hurricane) seasons becomes less intense, whilst the remainder of the year becomes wetter. Stratospheric aerosol injection is more effective than solar dimming in moderating extreme precipitation (and flooding). Despite the magnitude of the radiative forcing applied in G1 being ~7.7 times larger than in G4 and despite differences in the aerosol chemistry and transport schemes amongst the models, the two types of geoengineering show similar spatial patterns in normalized differences in extreme temperatures changes. Large differences mainly occur at northern high latitudes, where stratospheric aerosol injection more effectively reduces TNn and TXx. While the pattern of normalized differences in extreme precipitation is more complex than that of extreme temperatures, generally stratospheric aerosol injection is more effective in reducing tropical Rx5day, while solar dimming is more effective over extra-tropical regions.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 1556906
• Report Number(s): PNNL-SA-132309
• Journal Information: Atmospheric Chemistry and Physics (Online), Vol. 18, Issue 14; ISSN 1680-7324
• Publisher: European Geosciences UnionCopyright Statement
• Country of Publication: United States
• Language: English