7 May 2024

Silver Lining in the Clouds: Will the US Geoengineer?

David Shipton

Once denounced by former United States (US) Vice President Al Gore as “delusional in the extreme”, solar geoengineering is receiving greater attention from American scientists and policymakers. Increasingly pessimistic as to the prospects of existing strategies for addressing climate change and mindful of America’s acute vulnerability to its effects, these voices are challenging taboos by exploring alternative solutions to global warming. Solar geoengineering (SG) is a category of climate interventions which would mask the effects of global warming by reflecting incoming solar radiation. Amongst these interventions, the technology attracting the most attention is stratospheric aerosol injections (SAI), which mimic the cooling impact of volcanoes by injecting reflective aerosol particles into the stratosphere. In recent years, however, marine cloud brightening (MCB) has emerged as a credible alternative to SAI (increasingly considered a blunt and unwieldy environmental tool). Deployed at scale, MCB would alter the energy balance of Earth by seeding seawater aerosol above the ocean to produce more reflective clouds.

To its critics, SG is an unhelpful distraction from climate mitigation which risks unintended and uneven global effects and a dangerous securitisation of the environment. However, in light of the continued failure of climate mitigation and America’s tradition of scientific leadership and self-professed “exceptionalism”, this article explores the circumstances in which the US would deploy MCB to mask the impact of global warming in the coming decades. Whilst MCB appears practically feasible for a state with America’s resources, it is unclear whether there will be sufficient domestic support for its deployment, and the response of the international community is contingent upon its perceived impacts which are presently difficult to predict. This article identifies three conditions for a sustained US deployment of MCB and considers the circumstances in which they may each be met, outlined in turn below.

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