SRM approaches operate on a range of spatial scales. Some options for manipulating the reflectivity (albedo) of the Earth's surface are primarily local: while this means they are inherently limited in their effectiveness, it also means there are fewer potential complications in their implementation. At the other end of the spectrum, planetary scale options like stratospheric aerosol injection would affect the entire planet, with complex environmental, social and geopolitical consequences.2
SRM also encompasses a range of technological complexity. Some options involve nothing more complicated than painting roofs white. Others entail constructing fleets of high-altitude aircraft or even space-based mirrors. These latter methods have the most potential to offset the entire global climate warming, but involve resolving fundamental scientific questions, developing and implementing new technologies and addressing key governance challenges. The optimal solution may be one that uses SRM deployment alongside other climate responses such as emissions reduction and carbon dioxide removal.3 Overall, there is growing scientific consensus that this approach would work in a technical sense, with some limitations.45
However, all SRM approaches raise challenging questions such as who should control the technologies, if and when they should be deployed, and what should happen if a deployment goes wrong or fails entirely. Another concern is “moral hazard”: the possibility that investing in these SRM approaches would reduce the impetus to cut greenhouse gas emissions.
Given the increase in global mean temperatures, decisions about whether to research and deploy SRM are becoming increasingly urgent, but the political aspects of its implementation and subsequent governance remain highly problematic and poorly understood. There is thus a pressing need to develop international governance frameworks for deciding whether or not to conduct SRM field experiments; if so how — and to prepare for making decisions whether or not to deploy at some point in the future. Governance frameworks for potential future deployment need to be designed for the long term, because SRM deployment would need to be sustained and monitored for decades — and possibly a century or more.
SELECTION OF GESDA BEST READS AND KEY REPORTS:
In July 2023, an avant-garde proposition from István Szapudi, working at the university of Hawai’I, was presented in Solar radiation management with a tethered sun shield. Using a tethered sun shield positioned at a specific gravitational point, this article proposes a more efficient and cost-effective method for Solar Radiation Management, leveraging lunar dust or asteroids for most of its weight, revolutionising space-based climate interventions. In August, another innovative concept emerged from a collaboration between German, UK and US researchers in the publication titled Marine Cloud Brightening: an airborne concept. This paper sheds light on the promising method of employing drones to deliver industrially-produced salt nanoparticles, potentially revolutionising marine cloud brightening. The newfound efficiency, however, brings with it pressing governance dilemmas related to regional climate interventions. Also in August, researchers from the University of Bern provide a sobering perspective in Climate intervention on a high-emissions pathway could delay but not prevent West Antarctic Ice Sheet demise. While the potentials of Solar Radiation Modification are acknowledged, the research underscores the indispensable need for traditional emissions reduction to truly address the looming threat to the West Antarctic Ice Sheet.
