Scientists Warn Solar Geoengineering Poses Major Planetary Risks
8 reported3 unconfirmed
Four climate scientists have published an opinion piece in The Guardian warning that solar geoengineering and other large-scale climate intervention proposals carry significant risks and uncertainties. The authors, who collectively have studied climate physics for over 100 years, argue that solar geoengineering would not buy time for decarbonization and could lead to a catastrophic "termination shock" if the technology were ever stopped. They state that recent analyses show it would take up to two decades to build the required infrastructure, by which point the world would be completely reliant on maintaining it. The scientists note that climate model simulations so far do not agree on what level of intervention might be required or what the response would be, with global cooling ranging from less than 1C to as much as 3C after just 10 years of stratospheric aerosol injection. They also express concern about venture-capital funded startups, such as Stardust and Reflect Orbital, pursuing solar geoengineering deployment without governance frameworks.
What’s reported
Solar geoengineering proposals involve reducing sunlight and their effects decay in a matter of years, unlike carbon dioxide which remains in the atmosphere for millennia.
Recent analyses indicate it would take as long as two decades to create the required infrastructure for solar geoengineering.
A "termination shock" could occur if circumstances force the cessation of solar geoengineering, releasing pent-up warming catastrophically rapidly.
After only 10 years of stratospheric aerosol injection, global cooling could range from less than 1C to as much as 3C, according to the few models used so far.
The UK's Aria agency has funded a £60m geoengineering programme focused on technology development, often in collaboration with for-profit companies.
Israeli-US startup Stardust has received more than $60m in venture capital and assumes near-term deployment.
Reflect Orbital wants to put giant mirrors in low Earth orbit, pitching sales of illumination but using technology identical to solar geoengineering.
The authors state there is no rigorous modelling assessment exploring different solar geoengineering scenarios and no formal intercomparison of climate sensitivity to such interventions.
Open questions
Whether any governance framework for geoengineering can be established.
What the specific regional impacts of solar geoengineering would be on weather and climate variability.
Whether small-scale experiments can provide meaningful data about the effects of full deployment.
Misconceptions
The article addresses the misconception that solar geoengineering "buys time" for decarbonisation, stating it does not because it only temporarily masks pent-up warming and requires sustained maintenance.
Key figures
Raymond Pierrehumbert, Professor of Planetary Science at the University of Oxford, lead author on IPCC Third Assessment Report and US National Academy's first solar geoengineering report, Fellow of the Royal Society
Julia Slingo, formerly Chief Scientist of the UK Met Office, Fellow of the Royal Society, Dame Commander of the Order of the British Empire
Michael E Mann, Presidential Distinguished Professor in Earth and Environmental Science at the University of Pennsylvania, Member of the US National Academy of Sciences
Valerie Masson-Delmotte, Directeur de Recherche at the Climate and Environmental Sciences Laboratory, co-chair of IPCC Working Group 1 during AR6
Sources: The Guardian
