Geoengineering: The Ethical Risks of Stratospheric Aerosol Injections

What is Geoengineering?

Geoengineering is the deliberate large-scale modification of Earth’s natural systems by human beings with the aim of counteracting climate change. There are two main types of geoengineering: greenhouse gas removal (GGR) and solar radiation management (SRM). Both methods have the ultimate aim of reducing global temperatures but present different modes of action to achieve this goal. Greenhouse gas removal techniques address the root cause of climate change by removing greenhouse gasses from the atmosphere. Methods of GGR include afforestation, carbon capture and sequestration, ocean fertilization, among many others. Solar radiation management techniques, on the other hand, attempt to offset effects of increased greenhouse gas concentrations by causing the Earth to absorb less solar radiation (heat coming into the stratosphere from the sun), thus decreasing the temperature of Earth’s surface. Methods of SRM include albedo enhancement, space reflection technologies, and stratospheric aerosols. Solar radiation management techniques are the most popular geoengineering methods among political actors, with stratospheric aerosol initiatives being the preferred method. This method is specifically referred to as ‘sulfate aerosol geoengineering,’ which is the injection of sulfate aerosols (sulfur dioxide: a transparent substance that reflects light) into the stratosphere, increasing the Earth’s albedo and reflecting some of the incoming solar radiation back into space, resulting in a cooler planetary climate. 

Sulfate aerosol geoengineering (SAG) is rapidly developing above all other adaptation techniques because of its alleged low cost compared to other methods, its practical feasibility, the possibility of near instant climate gratification, and most importantly, the fact that its implementation does not require fundamental ideological and behavioral shifts worldwide. This technology implicitly suggests that international cooperation and radical lifestyle changes are not required to solve our climate crisis. If one buys into this incredibly optimistic and omitting solution, then the development and deployment of this technology seems like the obvious next step. However, the optimism regarding SAG, and solar radiation management techniques more generally, begins to fade when ethical concerns and risks are brought into the discussion. 

The History

In the year 2000, atmospheric chemist Paul Crutzen popularized the term ‘Anthropocene’ as a proposed geological epoch marked by significant human impact on the natural state of Earth’s systems. Since the rise of anthropogenic dialogue, humanity has increasingly acknowledged our misplaced confidence in the inherent stability of nature. Experts have repeatedly warned of devastating climate change, overpopulation, food scarcity, biodiversity loss, among many more concerns regarding humanity’s survival on this planet. We, humanity, have been warned many times of the need to reduce our fossil fuel emissions. Today, in 2022, the global climate is in overshoot. We can no longer contain the global average temperature to the required 1.5-2 degrees Celsius above pre-industrial levels through climate mitigation alone. How will humanity avoid the effects of significant climate change, some of which are deadly effects that lay in the near future? In 2006, Paul Crutzen once again spoke on the issue by publishing an article calling for geoengineers to address the climate crisis. Today, geoengineering initiatives and the associated technology are rapidly developing as scientists, engineers, and a large number of people have become increasingly cynical about our common future. Discussions regarding climate adaptation via technology are dominated by scientific, economic, and geopolitical academics. However, geoengineering initiatives also give rise to significant ethical questions and dilemmas, matters which urgently need to be discussed. 

Technocratic Solutionism

In 1964, environmental philosopher Lynn White published his essay “The Historical Roots of our Ecological Crisis,” arguing that the source of the ecological crisis was the union of science and technology, a union which created the ideology that humans could dominate nature. White’s essay highlighted how technological power has played a destructive force with drastic environmental consequences. This line of thinking was further developed by philosopher Alan Drengson who argued that most technological fixes proposed to solve environmental problems are built on the same premises which created the problems in the first place. The illusion of being able to completely understand, predict, and control weather and climate underestimates the complexity, fragility, and resilience of Earth’s systems. Geoengineering at large is ‘technological solutionism’, a dangerous approach which raises significant risks to the future of humanity and the planet. 

Humanity’s relationship with the environment is typically framed by the notion that we as human beings can control Earth’s systems to meet our desires. However, this type of thinking holds considerable error. The effects humanity has had, over many years, on the composition of Earth’s complex dynamical systems was largely unintentional. Influence does not necessarily entail control. The fact of the matter is that the climate is continuing to change counter to our desires as a species, and it is becoming increasingly urgent for us to account for these changes. Geoengineering is an attempt to answer this call for action. Geoengineers recognize that the climate is changing against humanity’s desires. However, the field continues to build solutions upon the deeply entrenched illusion that we will one day master nature. Geoengineers push for a more intentional Anthropocene, one in which humans act as the primary shaper of Earth’s climate through technology. What should be kept in mind, and in policy formation, is that technological solutions are often short-sighted and narrow-minded solutions, consequentially generating unforeseen consequences and the creation of new problems for our future. The environment and the future of the human species is not something that can be gambled on in such a way. 

The Ethical Risks of Sulfate Aerosol Geoengineering

Sulfate aerosol geoengineering threatens substantial harm to both humans and non-humans (plants/animals/systems) now and into the future. This technique of solar radiation management has the potential to harm through increased ocean acidification, alteration of regional precipitation patterns, the threat of unilateral implementation by one nation state or organization, and the chance of abrupt discontinuation leading to a rapidly warming climate, worse than the one we currently face. Given these risks of harm, SAG requires considerable ethical evaluation. 

1. Ocean Acidification:

Firstly, increased emissions of CO2 into the atmosphere are causing the world’s oceans to become more acidic; carbon dioxide is trapped in the atmosphere with a large portion being transferred to and absorbed by oceans. Increased CO2 levels in the oceans cause PH levels to decrease which results in acidification. Ocean acidification plays a considerable role in the decline of oceanic ecosystems, making them weaker and less resilient to natural and human-caused stressors. SAG techniques only compensate for planetary warming caused by incoming solar radiation, and not for the general accumulation of CO2 and other greenhouse gasses in the atmosphere. Thus, SAG techniques allow for CO2 levels to continue to rise, threatening substantial harm to humans who depend on marine ecosystems for their ecosystem services such as providing food and opportunities for income. Increased ocean acidification would also threaten substantial harm to marine organisms and ecosystems such as coral reefs, severely disrupting food webs and perhaps resulting in the collapse of interdependent food chains. This raises the ethical questions: What do we value more? Our current ways of living which SAG could temporarily maintain? Or sacrificing our current ways to save our oceanic systems for the future? 

2. Disrupted Hydrological Cycles:

Secondly, it was observed after the 1991 eruption of Mount Pinatubo in the Philippines that an increase in sulfur dioxide in the stratosphere upset hydrological (rain/water) cycles. From this observation it can be inferred that SAG techniques could potentially cause substantial reductions in average annual precipitation. This problem is compounded by the fact that some regions would be more affected by this change than others. Regions such as Africa, South America and South-Eastern Asia could face reduced freshwater availability, droughts, and significantly reduced agricultural productivity leading to famines and political upheaval. Changes in hydrological cycles also risk substantially harming terrestrial animals and plants, killing those which require specific ecological conditions to survive. This raises the ethical question: What if geoengineering benefits some while harming others? 

3. Unilateral Implementation:

A third ethical risk, connected to the second, is the threat that one nation state or organization could implement SAG technology unilaterally to its own self-interest because of its low cost and little need for global cooperation. The potential to implement this technology unilaterally risks concentrating power even further into the hands of the global elite to the detriment of those already suffering. This concern is furthered by the additional risk that SAG technology could be deployed by the same corporate interests that drive fossil fuel consumption, using the technology as an excuse to hold off on emission reduction efforts. These risks give rise to the ethical question: Does anyone have the right to manipulate the global environment?

4. Future Generations:

With further concern, there is the ethical risk of burdening future generations with the maintenance of SAG technologies. Solar aerosol geoengineering is a method which requires continual maintenance; the atmospheric lifespan of sulfur dioxide is only a few years and, as a result, would require continuous injections in order to maintain a constant level of global cooling. Unintentional discontinuation– caused by war, pandemic, or economic collapse for example– would lead to rapid global warming as global temperatures catch-up to the radiative forces of CO2 and other greenhouse gas concentrations. Thus, if SAG techniques were deployed, the present generation would be burdening future generations to actively maintain the technology– a responsibility for which they cannot possibly consent to and which they may not be able to fulfill, leading to their ultimate suffering. 

This discussion regarding the ethical risks associated with SAG technology is not exhaustive but functions to serve as a sample of the potential harm that solar aerosol geoengineering could bring to humans and non-humans both now and into the future. Solar radiation management techniques fail to provide adequate responses to these very significant ethical concerns, and therefore should not be taken as a promising solution for the climate crisis.

A Supplementary Solution: Ecological and Holistic Adaptation

To reduce concerns and risks in developing a climate crisis solution, it is imperative for humanity to focus on adaptation techniques which are reliable, ethical and ecological in both concept and practice. The question of how to save the planet from the effects of runaway climate change cannot be understood purely quantitatively. Geoengineering solutions are reductive, ethically intolerable, and ultimately rest on a destructive desire to control nature. When scientists and politicians reduce the complexity of the climate crisis to a technological task, they exclude many important factors of how Earth’s complex dynamical systems interact. We must recognize the fragility, resilience, and elements of agency within Earth’s systems when developing a solution to climate change. Creating adaptation solutions with these in mind opens humanity up to new paths for action. 

The global climate system has natural leverage points– points which can be targeted as methods for the reduction of atmospheric greenhouse gasses without entering the practice of technocratic solutionism. One such supplementary course of action is geo-therapy. Geo-therapy identifies the root cause of the climate crisis as a “failure to understand the balance that naturally keeps the climate stable, or that kept it stable before the industrial revolution.” Land regeneration tactics, such as afforestation and soil restoration projects, reduce the ethical risks which SAG solutions give rise to. Any mistakes made are localized and reversible because of their natural approach. These tactics take into consideration the specific needs of each location and system, instead of reducing a very complex problem into one singular task. Geo-therapeutic solutions are preferable methods because they effectively return the climate system closer to its natural state instead of moving further towards a human-dominated system. 

Adaptation and Mitigation Hand-In-Hand

It should be further pointed out that climate change cannot only be tackled through adaptation techniques alone. While these techniques can address atmospheric pollution that has occured in the past, it does not change nor stop the pollution that continues to happen in the present and in the future. Adaptation solutions need to be accompanied by mitigation solutions to be even remotely effective at solving the climate crisis. Ultimately, humanity must abandon the destructive and misguided conception that we are the masters of nature; humanity does not, and should not control Earth’s complex systems. To continue to think and behave as we do is to gamble with the future of the planet and our species.  


Crutzen, Paul. Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma. Climate Change 77, 2006. 

Fleming, James R. The Climate Engineers: Playing God to Save the Planet. The Wilson Quarterly, 1976. 

Meyer, Robinson. “What Happens If We Start Solar Geoengineering and Then Suddenly Stop?” The Atlantic, 2018. 

Rancourt, Benjamin T. The Ethics of Climate Change: Geoengineering and Geo-Therapy. Remineralize the Earth, 2017. 

Scott, Dane. Geoengineering and Environmental Ethics. Nature Education, 2012. 

Svoboda, Toby. The Ethics of Geoengineering: Moral Considerability and the Convergence Hypothesis: The Ethics of Geoengineering. Journal of Applied Philosophy 29, no. 2., 2012.

Hope Elizabeth Tracey
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  1. Hope Elizabeth Tracey, thanks for this eye opening enriched article immersed with brazen facts, I am truly inspired. You are correct, some of us are destroying what we do not understand, as a result their meddlesome interferences are successfully damaging our environment, and those who are feeling it the most are vulnerable populations indigenous to the earth crater and living off the land sustainable resources. We must never forget the ecosystem is oldest energy source.

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