We have just 12 years left to reduce emissions and achieve the Paris Agreement’s highest ambition of limiting warming to 1.5°C. We have been warned, repeatedly, of the high stakes of our present climate gamble. If we continue on our current course, radical solutions are going to be needed sooner rather than later.
Champions of solar radiation management (SRM) say this is the answer we’ve been looking for. SRM techniques cool the planet by reflecting sunlight away from it. The most discussed SRM technique involves continuously injecting tiny reflective particles – most often, sulphur – into the stratosphere to evenly cover the planet and shield us from the sun’s rays. Fleets of drones, or sprayers attached to enormous tethered balloons, could deliver these particles. Spray a little more, and the temperature drops; spray a little less, and the temperature rises.
Unlike the other dominant form of climate engineering, carbon dioxide removal, SRM does not extract greenhouse gases from the atmosphere. Rather, it masks the warming caused by those gases. Advocates say that SRM could give humanity a decent shot at getting its act together on mitigation. They also say the costs of SRM would be a fraction of the costs of the climate impacts we are facing without this technology.
However, there are reasons for caution, if not outright scepticism, about the wisdom of this techno-fix for climate change. One important worry relates to who governs research into SRM, given the risks it presents and its seductiveness as a “solution” to the climate crisis. There are some proposed self-regulations by SRM researchers, and more attention is being paid to international governance of SRM research, but a vacuum of governance remains.
To fill this vacuum in morally acceptable ways requires establishing governance to address the danger of sleepwalking into SRM “lock-in”, where a society becomes locked-in to a technology that has become too costly to abandon, even though alternative technologies may be better.
Once SRM deployment has begun, a status quo bias could quickly establish the new normal of a geoengineered world. It could combine with environmental generational amnesia, a phenomenon where generations of people forget previous environmental states and so don’t notice their deterioration. Those with their hands on the global thermostat – political leaders focused on short electoral cycles, and corporate leaders feeding the bottom line – would be tempted to continuously extend deployment to enable more and more business as usual.
A climate catastrophe
Imagine we become locked-in to a permanent geoengineered world in which SRM is being widely used but catastrophic climate change has been avoided. What’s the problem?
One potential big risk of widespread deployment of SRM is something called termination shock, where the technology is abruptly stopped, for example, by war, natural disaster, or sabotage. This would cause temperatures to rise very quickly to reflect the atmospheric concentration of greenhouse gases. If societies are locked into the technology, these speedy rises could be truly catastrophic. Even if SRM were to be used only temporarily, the long atmospheric life of C0₂ means that abrupt termination would still lead to a massive, swift warming effect.
SRM deployment is not an insurance policy against climate catastrophe. It creates new and terrible dangers of its own. We must not have a Panglossian view of the protection offered to us by existing institutions and the current global order. There needs to be governance of SRM research now that guards against lock in.
Catriona McKinnon receives funding from The Leverhulme Trust. She is a co-author of the Forum for Climate Engineering Assessment's report Governing Solar Radiation Management.