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

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.

Uncertainty and the basis for confidence in solar geoengineering research

“…SaG is designed to continually inject these aerosols (or their gaseous precursors, such as sulfur dioxide) in the stratosphere, maintaining cooling for as long as the injection is maintained 2 . This could be accomplished via numerous methods, but specially designed aircraft are likely to be most effective 156,157 . although sulfate aerosols are the most commonly discussed because of the natural analogue of volcanic eruptions, other aerosols (such as calcite) have been proposed 75 .…”

“…Medium; some uncertainty in estimates 156,157,172,173 Low; the costs are lower than any other method of addressing climate change…”

A specialised delivery system for stratospheric sulphate aerosols (part 2): financial cost and equivalent CO2 emission

“…McClellan et al 2010and Smith and Wagner (2018) propose specially developed aircraft for delivering aerosol precursors to the stratosphere. They estimate that these likely form realistic delivery platforms at a manageable financial cost per injected unit mass.…”

“…Furthermore, neither McClellan et al nor Smith and Wagner address the contribution to the atmospheric greenhouse gas concentration of developing, producing and operating a large fleet of aircraft for SAI (McClellan et al 2010;Smith and Wagner 2018). However, in order to make a full assessment of the risks and benefits of SAI, it is imperative to establish the carbon footprint of proposed delivery systems.…”

Governing Climate Engineering: A Proposal for Immediate Governance of Solar Radiation Management

“…SRM could also be relatively inexpensive, at least in terms of the direct costs associated with the physical act of altering planetary albedo. One study estimated the direct cost of a global SAI scheme at around $2.5 billion per year for the first 15 years [3], although other studies have estimated costs in the range of $10-20 billion per year [4] (cost estimates vary depending on assumptions of deployment technique and for given degrees of cooling). This is "cheap" when compared to the costs associated with mitigation, or when compared to the projected costs, including welfare costs, of unchecked atmospheric warming.…”