Ethics of Geoengineering


Until recently, the concept of geoengineering has widely been dismissed as a far-fetched and unethical idea to manipulate the environment. Geoengineering proposals intend to reduce the effects of global warming by manipulating the environment through extracting carbon dioxide from the air or reflecting sunlight to reduce global temperatures. However, as the context of climate change has shifted in urgency, geoengineering has emerged as a potential last-ditch effort to save humanity from climate-induced destruction. Despite its many unknowns and risks, geoengineering might provide a temporary solution to delay the detrimental effects of climate change and prevent the irreversible damage projected by current global warming trends.


As the threat of climate change has become more urgent, geoengineering has gained attention as a potential last-resort solution. Also known as climate intervention, geoengineering refers to the deliberate manipulation of the environment to reduce the effects of global warming. Presently, a lack of research and governmental support have prevented any geoengineering technologies from achieving full deployment, but current proposals fall into two main categories: Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM). The former proposes extracting CO2 from the air and sequestering it, potentially injecting it into saline aquifers where it will react with salt and solidify [1]. The latter intends to reflect solar radiation away from the earth to reduce surface temperatures in a wide variety of ways, including injecting aerosols into the atmosphere, sending large mirrors into orbit, creating vast areas of microbubbles in the ocean, or expanding clouds using saltwater spray, all of which will increase the area of light-colored surfaces that have the potential to reflect significant amounts of sunlight [2].

Since the first mention of geoengineering in 1841, when James Pollard Espy proposed artificially inducing rain in his book The Philosophy of Storms, climate intervention has widely been considered morally unacceptable [3]. Environmental ethics dominates the criticisms, arguing that this deliberate manipulation oversteps humankind’s proper relationship with nature. However, as the urgency of fighting climate change has rapidly increased, geoengineering can no longer be evaluated purely as a violation of the environment; instead, its potential for saving vulnerable human lives and preventing the suffering of future generations must be considered.

Environmental Considerations

From an environmental ethics standpoint, geoengineering is inherently immoral. This framework, used to evaluate the relationship between humankind and nature, advocates mainly that “Earth’s historical biogeochemical processes possess some moral significance in themselves” and requires humans to respect the natural resources, plant and animal interactions, hydrologic cycles, and weather fluctuations that Earth uses to regulate itself [5]. Historian Lynn White promotes this idea, blaming the ecological crisis on the modern era’s merging of science and technology that promoted humankind’s acceptance of technological power as a progressive force [6]. Human society has adopted the opinion that advancing civilization takes precedence over respecting the environment as a moral entity, but White argues that this self-declared role as “the exploiter of nature” is not an inherent right [6].

Manipulating Earth’s natural processes to geoengineer predetermined temperature levels, then, is a violation of the environment’s moral significance and an overstepping of humankind’s role in nature. For example, the SMR technology of aerosol injections seeks to mimic Mount Pinatubo’s 1991 volcanic eruption that cooled the planet 0.6˚C over the following two years [4]. The word “mimic,” though, exposes the inherent artificiality of this method, which will require a sustained and indefinite release of particles to maintain desired temperatures. This technology will create an artificial barrier in the atmosphere to prevent natural amounts of sunlight from reaching the plants, animals, and ecosystems that rely on existing sunlight levels.

Without a doubt, humankind has already violated White’s assertion that the environment possesses its own moral rights. Our civilizations depend on the burning of fossil fuels to power our vehicles, generate electricity, and produce household items. Human activity has caused global warming, so shouldn’t we have an obligation to reduce these impacts, regardless of the means? From an environmental ethics standpoint, the answer is no. According to this framework, the use of a technological fix would perpetuate the “mistaken philosophy” that “the proper human relationship to nature is the one of domination” [7]. According to professor of philosophy Eric Katz, “the insidious dream of domination can only end by respecting freedom and self-determination, wherever it exists, and by recognizing the true extent of the moral community in the natural world” [7].

Geoengineering, if deployed, would fight a man-made problem with a man-made solution, perpetuating the technological “treadmill” that carries human civilization. In addition to encouraging the domination of nature, geoengineering as a technical fix might create a domino effect of unwanted consequences. With the example of aerosol injections, the interception of sunlight could change rainfall patterns, potentially creating droughts or preventing seasonal monsoons [4]. Additionally, while the reflection of solar radiation might succeed in controlling Earth’s temperatures, it fails to reduce the carbon emissions that cause global warming. By masking the symptoms of the problem without actually solving it, these technologies will intervene in Earth’s natural ability to regulate itself, unbalancing its complex systems. The environmental ethics solution, therefore, would be to abandon technology and allow the environment to naturally stabilize its own temperatures.

Until recently, this desire to respect environmental ethics has caused widespread criticism and distrust of geoengineering ideas. The discussion on global warming mitigation has revolved around reducing fossil fuel usage and greenhouse gas emissions. The threat of climate change, however, has increased rapidly, and the time frame for preventing large scale and irreversible damage by reducing emissions is passing. As the climate situation has shifted, geoengineering has emerged as a potential solution to reduce deaths and suffering that will occur if the climate continues its current trajectory. With this growing urgency, the following question emerges: is it worth violating the climate’s natural processes to save Earth’s current inhabitants and future generations?

In 2015, 195 countries signed the Paris Agreement, pledging to cut their greenhouse gas emissions in order to keep global temperatures within the range of 1.5˚C to 2˚C above preindustrial temperature levels. If the climate rises above this threshold, the earth will experience irreversible and devastating damage far beyond the increase in wildfires, record-breaking heat waves, intensification of hurricanes and flooding, and melting of sea ice already evident. However, despite the Paris Agreement goals, fossil fuel emissions have continued to grow, increasing 1.5%, 2.1%, and 0.66% in 2017, 2018, and 2019, respectively [8]. The U.S., the second largest emitter of greenhouse gases, withdrew from the Paris Agreement in 2018 and has repealed over 80 federal environmental regulations, reducing its commitment to fight climate change [9]. The U.S. returned to the Paris Agreement in February 2021. However, scientists predict that to achieve the 1.5˚C goal, not only do emissions need to stop, but 100 to 1000 gigatons of CO2 must be removed within the century [10]. Without the intervention of geoengineering technologies, the climate is on track to cause irreversible destruction and suffering. 


To evaluate whether the benefits of geoengineering techniques outweigh the cost of violating the environment, we must look at the consequences of both scenarios: a world with geoengineering, and a world without. On its current trajectory, it is predicted that climate change will render 15-37% of land plants and animals extinct by 2050 [7]. If temperatures exceed the 2˚C threshold, famine, floods, heat waves, and human conflict could kill an estimated half-million people [11]. Beyond the 2˚C mark, the Committee on Climate Change estimates that a 4˚C increase will further restrict the water supply of an additional 250 million people, expose over a hundred million to flooding, and cause a drastic decline in crop production [11]. With geoengineering, this could be prevented. Even though geoengineering technologies might not be sustainable long-term solutions, they have the potential to keep these temperature increases from creating irreversible damage, buying time while society makes fundamental, sustainable changes to reduce fossil fuel dependence.

However, along with the life-saving potential of geoengineering technologies comes the risk of severe negative consequences. For instance, researchers worry that spraying aerosols into the atmosphere could deplete the ozone layer, increasing rates of skin cancer or preventing plants from undergoing photosynthesis [7]. Models have also shown that deploying aerosol injections in the Northern Hemisphere could decrease rainfall in India and Africa, creating deadly droughts [2]. Furthermore, should geoengineering technologies suddenly be withdrawn, the rapid warming that would follow could be life-threatening to humans, animals, and plants, since there would be little time to adapt.

The unknowns of geoengineering make it extremely difficult to evaluate whether the benefits will outweigh the costs. Due to geoengineering’s world-wide impacts, only small-scale testing has occurred so far. Models can predict the effects and consequences of geoengineering, but their accuracy is questionable. Thus, the question at hand is not whether full-scale deployment should occur, but rather whether attention and funding should be given to research.

From a utilitarian standpoint, it is morally prudent to support research into geoengineering technologies. This approach to ethics, promoted by theorists Jeremy Bentham and John Stuart Mill, evaluates morality based on the minimization of pain and maximization of benefits [12]. In 1997, physicist Edward Teller at the Lawrence Livermore National Laboratory published a report estimating that the benefits of geoengineering could potentially outweigh the costs of allowing greenhouse gases to continue destroying the environment by a factor of 100 [13]. Although that is a speculative figure, it represents a scenario in which the wide-scale benefits of geoengineering warrant the localized negative costs. Furthermore, the utilitarian approach, which evaluates the ends rather than the means, justifies violating the environment’s processes for the sake of saving human, animal, and plant lives.

Human Rights

Another approach to comparing the consequences of geoengineering with the consequence of global warming is with a rights-based framework. According to the Universal Declaration of Human Rights, a 1948 proclamation by the United Nations, every human has the right to “a standard of living adequate for the health and well-being of himself and of his family” [14]. This includes the fundamental rights to be free from food insecurity, thirst, and malnutrition. The dangers of climate change, therefore, will deprive millions of humans of these rights by causing droughts, depleting their food sources, and creating natural disasters that cause displacement and death. According to the director of the Harvard University Center for the Environment, “the most likely scenarios for climate over longer time scales are devastating to future generations, absolutely dangerous” [9]. Thus, to ignore the potential of geoengineering to prevent climate-induced suffering would be to consciously allow climate change to strip humans of their inherent rights.

Distributive Justice

Since geoengineering is a global issue and all humans are stakeholders, distributive justice must be considered. This term refers to the extent to which burdens and benefits are distributed across society. Part of the concern over geoengineering proposals is that their negative effects could harm various countries in disproportionate ways, such as increasing drought specifically in Africa and Asia. This is a valid concern, and before any technologies can be deployed, more research into geoengineering technologies is necessary to confirm risks and mitigate such injustices. The University of Montana’s Ethics of Geoengineering Online Resource Center requires a moral obligation for research to seek the inclusion of marginalized people [5]. By representing vulnerable populations in research, the needs and burdens of these societies can be illuminated and addressed. Furthermore, health researcher Elizabeth Morrow suggests that geoengineering research should be governed using the basic principles of medical ethics, namely the principles of beneficence and justice, which require a fair distribution of benefits or harms. This means that deployment of geoengineering should only occur when there is evidence that vulnerable populations are not disproportionally negatively affected [5].

Distributive justice can also be used to evaluate the effects of climate change without the intervention of geoengineering. Already, global warming is unfairly affecting vulnerable populations, exacerbating drought and malnutrition in poorer communities that do not have the resources to protect themselves. Marginalized populations depend more heavily on local ecosystems for survival, so they are more directly impacted by the decreased crop yields, increased flooding, and deadly heat waves caused by global warming [15]. In a wholly disproportionate distribution of justice, these communities suffering the most have contributed the least to climate change, since they consume less fossil fuel and energy than wealthy populations. In the words of journalist Anna Pujol Mazzini, “Geoengineering has a humanitarian mission – relieving suffering of the most vulnerable,” in order to create a more fair distribution of climate effects [16].

In addition to currently vulnerable populations, distributive justice evaluations must extend to future generations. Even though they do not have a voice in today’s conversation, our actions will impact future generations, who will suffer the increasingly devastating effects of climate change. While we have the chance now, it is important to support research to improve geoengineering technologies and understand their risks before large-scale climate-induced hardships and deaths become imminent. We have a moral obligation to protect the future, meaning we must be prudent now and put funds and effort into research, so that if or when the situation becomes dire, future generations have tools for immediate action.


Ultimately, geoengineering is a concept rife with potential benefits, risks, ethical concerns, and environmental issues. Even if further research confirms its viability, the ethical implications reach beyond the contents of this paper. Geoengineering could easily prove a moral hazard if it is promoted as a cheap technological replacement for the need to reduce emissions [7]. On the other hand, increased research in geoengineering technologies might instead emphasize the urgency of global warming, encouraging more efforts to reduce emissions. Additionally, other ethical issues arise regarding governance and deployment. An unprecedented global governance structure will need to be created to determine how these technologies and their global effects are controlled [9].

Presently, the ethical course of action is to continue research to address risks and minimize consequences in order to create feasible technologies. Should geoengineering eventually be deployed, ethicists agree that it must be used as a supplement to greenhouse gas reduction, not a replacement [17]. As emissions continue to grow and the window of opportunity shrinks, increased research can investigate alternative methods that result in the least harm. For instance, if aerosol injection using sulfate particles depletes the ozone, further research can investigate alumina, diamond dust, or calcium carbonate as other options [11]. Even if geoengineering is not the ideal solution, especially in terms of environmental ethics, it has the potential to delay the effects of climate change and buy time for the world to make fundamental and sustainable changes in energy usage. In the face of the looming climate crisis, geoengineering must be considered as a feasible way to buy time, because ignoring its potential to save lives risks seriously and irreversibly endangering humankind.

By Sarah Cigas, Viterbi School of Engineering, University of Southern California

About the Author

At the time of writing this paper, Sarah Cigas was a senior studying civil engineering with a minor in East Asian Area Studies. She is from Kansas City, MO and plans on becoming a structural engineer.


[1] E. Kolbert, “Climate Solutions: Is It Feasible to Remove Enough CO2 from the Air?,” Yale E360, 15-Nov-2018. [Online]. Available: [Accessed: 25-Mar-2020].

[2] “Explainer: Six ideas to limit global warming with solar geoengineering,” Carbon Brief, 27-Feb-2019. [Online]. Available: [Accessed: 25-Mar-2020].

[3] T. McCormick, “Geoengineering: A Short History,” Foreign Policy, 03-Sep-2013. [Online]. Available: [Accessed: 10-Apr-2020].

[4] F. Pearce, B. Gardiner, and J. Robbins, “Geoengineer the Planet? More Scientists Now Say It Must Be an Option,” Yale E360. [Online]. Available: [Accessed: 29-May-2019].

[5] “Ethics of Geoengineering,” Ethics Overview – University Of Montana. [Online]. Available: [Accessed: 10-Apr-2020].

[6] L. White, “The Historical Roots of Our Ecologic Crisis,” Science, vol. 155, no. 3767, pp. 1203–1207, Oct. 1967.

[7] D. Scott, “Geoengineering and Environmental Ethics,” Nature Education Knowledge, 2012. [Online]. Available: [Accessed: 10-Apr-2020].

[8] R. B. Jackson1, P. Friedlingstein2, R. M. Andrew4, J. G. Canadell5, C. L. Quéré6, and G. P. Peters4, “IOPscience,” Environmental Research Letters, 04-Dec-2019. [Online]. Available: [Accessed: 26-Mar-2020].

[9] C. Lin, “Is Geoengineering the Solution to Climate Change?,” The Bull & Bear, 07-Apr-2020. [Online]. Available: [Accessed: 10-Apr-2020].

[10] “Geoengineering is no climate fix. But calling it a moral hazard could be counterproductive,” Bulletin of the Atomic Scientists, 10-Dec-2019. [Online]. Available: [Accessed: 26-Mar-2020].

[11] J. Temple, “The Growing Case for Geoengineering,” MIT Technology Review, 02-Apr-2020. [Online]. Available: [Accessed: 09-Apr-2020].

[12] “Environmental Ethics,” Internet Encyclopedia of Philosophy. [Online]. Available: [Accessed: 12-May-2020].

[13] K. Caldeira and G. Bala, “Reflecting on 50 years of geoengineering research,” AGU Journals, 12-Jan-2017. [Online]. Available: [Accessed: 25-Mar-2020].

[14] “Universal Declaration of Human Rights,” United Nations. [Online]. Available: [Accessed: 12-May-2020].

[15] J. Horton, “One Good Reason Why the Left Should Give Geoengineering a Second Look,” Forum for Climate Engineering Assesment, 05-May-2015. [Online]. Available: [Accessed: 12-Apr-2020].

[16] D. Dunne, “Geoengineering: Scientists in Berlin debate radical ways to reverse global warming,” Carbon Brief, 05-Feb-2019. [Online]. Available: [Accessed: 22-Mar-2020].

[17] D. Morrow, “Some ethical issues in geoengineering,” C2G: Carnegie Climate Governance Initiative, 21-Dec-2017. [Online]. Available: [Accessed: 09-Apr-2020].

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