Stratospheric aerosol injection

Solar radiation reduction due to volcanic eruptions, considered the best analogue for stratospheric aerosol injection.

Stratospheric aerosol injection (SAI) is a proposed method of solar geoengineering (or solar radiation modification) to reduce global warming. This would introduce aerosols into the stratosphere to create a cooling effect via global dimming and increased albedo, which occurs naturally from volcanic winter.[1] It appears that stratospheric aerosol injection, at a moderate intensity, could counter most changes to temperature and precipitation, take effect rapidly, have low direct implementation costs, and be reversible in its direct climatic effects.[2] The Intergovernmental Panel on Climate Change concludes that it "is the most-researched [solar geoengineering] method that it could limit warming to below 1.5 °C (2.7 °F)."[3] However, like other solar geoengineering approaches, stratospheric aerosol injection would do so imperfectly and other effects are possible,[4] particularly if used in a suboptimal manner.[5]

Various forms of sulfur have been shown to cool the planet after large volcanic eruptions.[6] However, as of 2021, there has been little research and existing natural aerosols in the stratosphere are not well understood.[7] So there is no leading candidate material. Alumina, calcite and salt are also under consideration.[8][9] The leading proposed method of delivery is custom aircraft.[10]

  1. ^ Crutzen PJ (2006). "Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?". Climatic Change. 77 (3–4): 211–220. Bibcode:2006ClCh...77..211C. doi:10.1007/s10584-006-9101-y.
  2. ^ Climate Intervention: Reflecting Sunlight to Cool Earth. Washington, D.C.: National Academies Press. 23 June 2015. doi:10.17226/18988. ISBN 9780309314824. Archived from the original on 22 November 2021. Retrieved 18 November 2015.
  3. ^ Global warming of 1.5°C. [Geneva, Switzerland]: Intergovernmental Panel on Climate Change. 2018. p. 350. ISBN 9789291691517. OCLC 1056192590.
  4. ^ Cziczo DJ, Wolf MJ, Gasparini B, Münch S, Lohmann U (11 December 2019). "Unanticipated Side Effects of Stratospheric Albedo Modification Proposals Due to Aerosol Composition and Phase". Scientific Reports. 9 (1): 18825. Bibcode:2019NatSR...918825C. doi:10.1038/s41598-019-53595-3. ISSN 2045-2322. PMC 6906325. PMID 31827104.
  5. ^ Daisy Dunne (11 March 2019). "Halving global warming with solar geoengineering could 'offset tropical storm risk'". CarbonBrief. Archived from the original on 26 March 2019. Retrieved 14 March 2019.
  6. ^ Rasch PJ, Tilmes S, Turco RP, Robock A, Oman L, Chen CC, Stenchikov GL, Garcia RR (29 August 2008). "An overview of geoengineering of climate using stratospheric sulphate aerosols". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 366 (1882): 4007–4037. Bibcode:2008RSPTA.366.4007R. doi:10.1098/rsta.2008.0131. PMID 18757276. S2CID 9869660.
  7. ^ Tollefson J (29 March 2021). "US urged to invest in sun-dimming studies as climate warms". Nature. doi:10.1038/d41586-021-00822-5. PMID 33785925. S2CID 232431313. Archived from the original on 25 August 2021. Retrieved 25 August 2021.
  8. ^ Keith DW, Weisenstein DK, Dykema JA, Keutsch FN (27 December 2016). "Stratospheric solar geoengineering without ozone loss". Proceedings of the National Academy of Sciences. 113 (52): 14910–14914. Bibcode:2016PNAS..11314910K. doi:10.1073/pnas.1615572113. PMC 5206531. PMID 27956628.
  9. ^ Voosen P (21 March 2018). "A dusting of salt could cool the planet". Science | AAAS. Archived from the original on 25 August 2021. Retrieved 25 August 2021.
  10. ^ Pierce JR, Weisenstein DK, Heckendorn P, Peter T, Keith DW (2010). "Efficient formation of stratospheric aerosol for climate engineering by emission of condensible vapor from aircraft". Geophysical Research Letters. 37 (18): n/a. Bibcode:2010GeoRL..3718805P. doi:10.1029/2010GL043975. S2CID 15934540.