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Solar geoengineering and stratospheric aerosol injection has received enormous amounts of pushback from scientists, environmental groups, and indigenous communities

Summary​

Stratospheric aerosol injection faces significant opposition from scientists, environmental groups, and indigenous communities. Key concerns include its potential to distract from emissions reduction efforts (moral hazard), technical uncertainties in climate modeling, and risks like ozone depletion and termination shock. Governance challenges arise from cross-border impacts and power imbalances between nations capable of deployment. Recent incidents highlight legal conflicts and accusations of climate colonialism when experiments by an American startup company proceed without local consent. Indigenous groups particularly oppose SAI as violating natural world relationships. While some argue specialized governance might be feasible, critics maintain current international frameworks are inadequate for managing SAI's global risks and ethical dilemmas.

SAI is a highly contentious topic in the scientific community and is generally unsupported by the majority of environmental activist organizations and indigenous groups. Listed below are a handful of the main arguments against solar geoengineering. This fact page is not intended to debunk these arguments, but rather to inform readers about the current climate of public opinion on SAI.

Moral Hazard: SAI is a distraction from the need to rapidly decarbonize the global economy​

Opponents of SAI argue that it is a distraction from the need to rapidly decarbonize the global economy and that it will allow countries and corporations to continue to burn fossil fuels and emit greenhouse gases without consequence 1.

SAI and all solar geoengineering projects will not work.​

Opponents of solar geoengineering argue that due to the immense complexity and coupling of the Earth's climate system, any large-scale intervention will further destabilize the Earth's climate system. Many point to the large degree of uncertainty and the high degree of mathematical assumptions input into global climate models that are used to predict the effects of SAI. While many climate models predict a reduction in global temperatures due to aerosol-induced global dimming, these same models often overlook the complex regional climate systems that may negate the global temperature reduction 2.

Solar geoengineering is too risky and carries too much uncertainty​

Opponents argue that even if solar geoengineering were to work, the potential risks outweigh the benefits. These risks include:

It is impossible to test solar geoengineering​

Solar geoengineering as a concept and as a deployable technology is untestable outside of computer-based climate modeling. As such, any real-world experiment that may yield measurable reductions in global temperatures would inherently no longer be an experiment and would equal deployment. This makes it difficult to fully evaluate many of the potential risks and benefits of solar geoengineering. SAI is a long-term project that would need to be sustained over a long time period before any results would be observed. If an SAI experiment were to be conducted, and the cooling results were of a higher magnitude than expected, it would be difficult to scale back the program due to the risk of termination shock.

Solar geoengineering breaks international law​

Opponents of SAI and solar geoengineering argue that these interventions would break international law and undermine national sovereignty. As recently as 2023, the Mexican government banned all solar geoengineering experiments in response to a recent experiment by a small startup company called 'Make Sunsets'. The company used balloons to release small amounts of sulfur dioxide into the atmosphere without first consulting with indigenous peoples who lived in the area 3. This creates a complex situation when aerosols from SAI experimentation in neighboring countries, mainly the United States, cross the border into Mexico, breaking local laws. This incident is also seen as an example of 'climate colonialism' when wealthy entities use poorer countries as their testing ground for new technologies.

Solar geoengineering would require an unachievable level of governance.​

Opponents argue that the level of governance required to implement SAI would be unachievable. Currently, there is no global system of international governance in place to oversee the experimentation of SAI, let alone its deployment. Additionally, due to the cost and required technology for SAI, only a small handful of nations possess the capabilities, which would create a power imbalance within the governance system. However, as SAI is a single issue, it is argued that establishing global SAI governance may be easier than establishing global governance to address climate change and CO2 reduction 4.

Solar geoengineering is rejected by indigenous groups​

Many indigenous groups view SAI and solar geoengineering as unprecedented attempts to drastically alter the Earth, violating the intrinsic relationship between humans and nature 5. As such, experimentation of SAI is viewed as a human rights abuse of indigenous peoples and a threat to their way of life. Strong pushback by indigenous groups, mainly the Saami Council, led to the cancellation of the Harvard University Stratospheric Controlled Perturbation Experiment (SCoPEx) after they attempted to move the experiment to Sweden.

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Footnotes​

  1. Stephens, J. C., Kashwan, P., McLaren, D., & Surprise, K. (2021). The dangers of mainstreaming solar geoengineering: A Critique of the National Academies report. Environmental Politics, 32(1), 157-166. https://doi.org/10.1080/09644016.2021.1989214 ↩

  2. Bednarz, E. M., Visioni, D., Banerjee, A. A., Braesicke, P., Kravitz, B., & MacMartin, D. G. (2022). The overlooked role of the stratosphere under a solar constant reduction. Geophysical Research Letters, 49. https://doi.org/10.1029/2022GL098773 ↩

  3. ETC Group. (2023, January 17). Mexico sets a global precautionary example by stopping solar geoengineering experiments. https://www.etcgroup.org/content/mexico-sets-global-precautionary-example-stopping-solar-geoengineering-experiments ↩

  4. Humphreys, D. (2011). Smoke and mirrors: Some reflections on the science and politics of geoengineering. Journal of Environment & Development, 20(2), 99-120. https://doi.org/10.1177/1070496511405152 ↩

  5. Saami Council. (2021, June 9). Petition to shut down the SCoPEx project. Saami Council. https://www.saamicouncil.net/news-archive/support-the-indigenous-voices-call-on-harvard-to-shut-down-the-scopex-project ↩