Solar Geoengineering: the Unknowns, the Risks, and the Potential Benefits
Careful investigations are needed to understand the trade-offs involved in any attempts to engineer the Earth’s climate. An outright ban on solar geoengineering may not be the appropriate response.
By Abigail Jackson
ANTHROPOGENIC CLIMATE CHANGE has precipitated one of the most complex public policy challenges of the 21st century. Extreme weather events are already affecting the lives of billions of people around the world each year, and recent reports by the Intergovernmental Panel on Climate Change (IPCC) warn that the world will face irreparable damages even if global warming is limited to 1.5 degrees Celsius from pre-industrial levels.
With no time to lose and a slim margin for error, the alarm bells have started ringing. Some policymakers are starting to wonder, what happens if we cannot limit global warming fast enough? Should we have a backup plan? And would the potential costs of that backup plan be worth it?
Solar geoengineering technology offers an opportunity to cool the earth and reduce some of the most catastrophic effects of climate change. It consists of the large-scale re-engineering of the environment through changes in atmospheric chemistry, offering a relatively quick and inexpensive method to lower the Earth’s temperature.
The process would include flying planes at high altitudes to deposit a layer of particles into the stratosphere. These particles would create a reflective shield between the Earth and the sun, and could effectively block some of the sun’s rays to rapidly cool the surface of the planet.
Promising as this sounds, solar geoengineering comes with significant unknowns and risks. Potential risks of solar geoengineering include changes to the ozone layer, unpredictable changes in regional weather patterns, reductions in global precipitation levels, unknown effects on plants that rely on direct sunlight, and the termination shock that could take place if the process were to be ended abruptly.
Even with this already extensive list of possible side effects, research on solar geoengineering is still in its nascence. Therefore, the full range of its potential risks and benefits are not yet fully known. This creates a tricky question for climate policymakers: should solar geoengineering research be allowed, or should it be banned out of precaution?
Solar geoengineering is not a new idea. In 1992, a climate change report from the US National Academies discussed options for geoengineering, including both carbon capture and storage as well as the practice of reflecting sunlight away from the earth. Yet solar geoengineering remained on the fringes of climate-science discourse until a prominent atmospheric ozone scientist, Paul Crutzen, published an article in 2006 discussing it as a valid policy option.
After this, research opportunities began to gain traction. In 2017, Harvard University launched its Stratospheric Controlled Perturbation Experiment to expand research on the science and governance of solar geoengineering. However, its on-the-ground experiments have largely been stalled due to local opposition and controversies related to the role of oil companies as private funders.
More recently, progress has been made by some scientists who advocate for more research in the still largely unexplored field by promoting solar geoengineering as a complement to climate action, not a substitute. This view is catching on, with prominent research bodies (including the IPCC) now considering the role of geoengineering techniques such as solar radiation modification in climate action responses.
However, the science of solar geoengineering is still largely based on data from past volcanic eruptions that demonstrated the cooling effects of massive clouds of sulfur dioxide in the upper atmosphere. Other than these volcanic eruptions, most of what scientists know comes from models, leaving much to be discovered. Additional research in this area is critical because the consequences and benefits alike are still so poorly understood – and the stakes are very high.
Yet even this very research is in itself controversial. Experiments have thus far been limited largely due to ideological and moral arguments, grounded in the concern that research may engender moral hazards that could negatively affect efforts to reduce emissions at a time when those efforts are most needed. This is connected to the risk that pursuing this novel research may waste resources that could have otherwise gone toward the time-sensitive task of reducing emissions.
Others worry that there will be unintended consequences or that it will be difficult to establish a system of global governance around this complex research area. Some also fear that a better understanding of geoengineering technology may encourage people to actually try it despite the many potential risks, especially if the practice becomes normalized. Finally, there is always the risk that an experiment could go wrong and negatively affect humans and the planet alike.
However, banning research also comes with risks, including the possibility that researchers may be pushed underground where they would operate without international guidelines, expectations, or accountability. A ban could also create “substitution risks” by which other and potentially even more dangerous options could be considered in place of solar geoengineering. Some scholars also worry about the risk that a ban could inadvertently make the technology look “too good” by not allowing scientists to prove that this otherwise appealing technology is harmful.
Conversely, research could shine more light on the risks of solar geoengineering in a way that ensures future generations don’t use the technology if it is, in fact, as dangerous as we predict. Furthermore, a ban on research would withhold the option from future generations to make a fully informed decision about climate action, creating increased risks for them as the worst effects of climate change unfurl.
As the window to prevent the worst effects of climate change continues to shrink with each passing day, policymakers have a responsibility to assess the current research on geosolar engineering and decide whether the unknowns and risks warrant precautionary action. Given that there are risks associated with both allowing research as well as banning it, this is no easy task. However, one thing is clear: more data can tell policymakers more about the risks and benefits of solar geoengineering, which could help to inform policy decisions.
Governments could choose to ban solar geoengineering research out of precaution, but this would require a coordinated effort by global policymakers to ban the research internationally to be effective. As such, this policy option may be politically difficult to carry out. In contrast, by allowing solar geoengineering research, policymakers could foster a global community of accountable practice that could pool information and allow for more informed decisions about using the technology.
One avenue to investigate could be in allowing only publicly funded research, which could improve the ability of governments to regulate research to monitor for risks. To address the issue of moral hazard, governments could stipulate that funding provided for research must be paired with additional research on emission reductions.
In this way, policymakers would have to walk a fine line between balancing potential benefits and risks, but, if done well, this could foster critical knowledge development and information sharing on the possibility of solar geoengineering as a backup policy option to fight rising temperatures.
As climate change disasters increase in frequency and intensity, it is likely that people around the world will rise up and call on their states to do something to protect them. Solar geoengineering is a policy option that is increasingly discussed, and policymakers should be ready to consider it with both precaution and justice in mind.
Abigail Jackson is a Master of Public Policy candidate with the Max Bell School of Public Policy at McGill University and the 2023 co-recipient of the Jack Layton Prize for a Better Canada. Abigail is pursuing her MPP degree to expand her knowledge of complex policy systems so that she can use her analytical mindset and creativity to make valuable contributions to environmental policy and governance. Topics that interest her include sustainable food systems, post-consumer waste streams, and energy efficiency in building.