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Cited by 181Climate Change and GeoengineeringAtmospheric aerosols and cloudsAdvanced Aircraft Design and Technologies

Stratospheric aerosol injection tactics and costs in the first 15 years of deployment

Open access
Smith, Wake, Wagner, Gernot·2018·Environmental Research Letters
DOI 10.1088/1748-9326/aae98d
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Abstract

We review the capabilities and costs of various lofting methods intended to deliver sulfates into the lower stratosphere. We lay out a future solar geoengineering deployment scenario of halving the increase in anthropogenic radiative forcing beginning 15 years hence, by deploying material to altitudes as high as ∼20 km. After surveying an exhaustive list of potential deployment techniques, we settle upon an aircraft-based delivery system. Unlike the one prior comprehensive study on the topic (McClellan et al 2012 Environ. Res. Lett. 7 034019), we conclude that no existing aircraft design—even with extensive modifications—can reasonably fulfill this mission. However, we also conclude that developing a new, purpose-built high-altitude tanker with substantial payload capabilities would neither be technologically difficult nor prohibitively expensive. We calculate early-year costs of ∼$1500 ton −1 of material deployed, resulting in average costs of ∼$2.25 billion yr −1 over the first 15 years of deployment. We further calculate the number of flights at ∼4000 in year one, linearly increasing by ∼4000 yr −1 . We conclude by arguing that, while cheap, such an aircraft-based program would unlikely be a secret, given the need for thousands of flights annually by airliner-sized aircraft operating from an international array of bases.

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Integrity signals

Registry

Crossref · 10.1088/1748-9326/aae98d

Cites

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  • Key aircraft cost factors presented in table 5 are generally consistent with (and in many cases identical to) those presented in Smith and Wagner (2018), at least in the early years.

    “Key aircraft cost factors presented in table 5 are generally consistent with (and in many cases identical to) those presented in Smith and Wagner (2018), at least in the early years.”

    From The cost of stratospheric aerosol injection through 2100 (2020) · cites this paper as Smith and Wagner (2018)

    Table 4 (section 6; page not available) lists aircraft operating-cost factors, and Table 5 gives costs by deployment year. Our copy does not contain the citing document’s Table 5, so it cannot establish that its factors are generally consistent with, or identical to, these factors in the early years. (LLM, conf=0.78)

    Experimental — accuracy not yet measured

  • For the reasonably foreseeable future, the lofting solution that best minimizes both technology risk and cost is a newly designed fleet of high-altitude tanker aircraft.

    “Reliance is also made upon the conclusion that, for the reasonably foreseeable future, the lofting solution that best minimizes both technology risk and cost is a newlydesigned fleet of high-altitude tanker aircraft (Smith and Wagner 2018).”

    From The cost of stratospheric aerosol injection through 2100 (2020) · cites this paper as Smith and Wagner 2018

    Section 3 compares lofting technologies and rules out several as too immature, unable to reach the required altitude, or substantially more costly. Section 4.1 describes a new aircraft designed for the mission. The conclusion is bounded by the paper’s first-15-years deployment scenario: Section 4.3 says a later-generation solution could instead use a non-aircraft technology, so the broader claim about the reasonably foreseeable future overstates its scope. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

  • SAI can rapidly reduce global temperatures for costs on the order of $10 billion per year per C of cooling.

    “With the ability to rapidly reduce global temperatures for costs on the order of $10 billion per year per C of cooling2”

    From Engineering and logistical concerns add practical limitations to stratospheric aerosol injection strategies (2025) · cites this paper as [2]

    The deployment scenario (section 2) projects a 0.2°C reduction in global average temperature relative to the baseline per decade, and the further discussion (section 6) estimates average direct operating costs of about $2.25 billion per year—figures broadly consistent with an order-of-magnitude estimate of $10 billion per year per °C. But the paper does not estimate the cost of achieving a full 1°C of cooling; it also says deployment would take several years to ramp up and excludes indirect costs. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Longitude of injection has been assumed to be somewhat arbitrary in most simulations, with longitudinal transport evenly dispersing aerosols zonally.

    “Longitude of injection has been assumed to be somewhat arbitrary in most simulations2,25, with longitudinal transport evenly dispersing aerosols zonally.”

    From Engineering and logistical concerns add practical limitations to stratospheric aerosol injection strategies (2025) · cites this paper as [2]

  • Estimates for cost of sulfur-based deployments stem nearly entirely from aircraft-related expenses, making such decreases in payload likely to significantly impact costs.

    “Estimates for cost of sulfur-based deployments stem nearly entirely from aircraft-related expenses, making such decreases in payload likely to significantly impact costs2.”

    From Engineering and logistical concerns add practical limitations to stratospheric aerosol injection strategies (2025) · cites this paper as [2]

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Authors
Smith, W., & Wagner, G.
Affiliations
  • Yale University (US)
  • Harvard University (US)
Corresponding author
Wagner, Gernot
ORCID
Venue
Environmental Research Letters
Publisher
IOP Publishing
Published
2018-11-22
Volume
13
Issue
12
Pages
124001
ISSN
1748-9326 (ISSN-L)
DOI
10.1088/1748-9326/aae98d
OpenAlex
W2901600470
Cited by
181
References
44
Citations by year
2026: 10 · 2025: 21 · 2024: 15 · 2023: 19 · 2022: 35 · 2021: 25 · 2020: 24 · 2019: 31 · 2018: 1
FWCI
11.86
Type
journal article
Language
en
Open access
Licence
Locations
  • Environmental Research Letters (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
Funders
National Aeronautics and Space Administration
Topics
  • Physical Sciences › Environmental Science › Global and Planetary Change › Climate Change and Geoengineering
  • Physical Sciences › Environmental Science › Global and Planetary Change › Atmospheric aerosols and clouds
  • Physical Sciences › Environmental Science › Global and Planetary Change › Advanced Aircraft Design and Technologies
Keywords
solar geoengineering, stratospheric aerosol injection, sulfate aerosols, deployment cost

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