Shivani Dharanipragada ‘25, is a computer science and economics major and was a 2022-23 environmental ethics fellow with the Markkula Center for Applied Ethics. Views are her own.
As Earth’s climate takes a turn for the worse, scientists are researching new methods to potentially slow the advancement of climate change. One of these methods is geoengineering: intentionally engineering the Earth’s climate in order to slow or stop global warming.
There are many ideas that have been proposed as potential solutions: stratospheric particle injection, marine cloud brightening, space reflectors, desert modification, large-scale direct air capture, enhanced rooftop reflectivity, the list goes on and on. To read more about proposals for climate engineering, click here . These implementations could work, in theory, however, these climate-altering technologies must be implemented in reality and on a global-scale in order to change the climate. Yet much of the research done on climate engineering is theoretical and small-scale, with “little experimental work and limited geographic diversity” . So, could they be effective? On some level, that’s unknown. However, even if they were, the better question is: are they practically implementable? In this article, “practically implementable” is defined as something that would be cost-effective and politically acceptable. Thus, here we will consider the efficacy, economics, and politics of these technologies.
I. Cost - Effectiveness
Could climate engineering effectively counteract global warming? And how much would it cost? Cost and efficacy are two factors that a successful business model prioritizes above all. Realistically, most governments (the most likely organizations to implement climate engineering) will also prioritize these elements.
So, is climate engineering cost-effective? The answer is that it depends, at least according to a study by Michael Zürn and Stefan Schäfer, which measured climate engineering’s efficacy by its capability to lower global mean temperatures “as a single measure in a relatively short period of time” . For example, some proposed climate engineering methods are too weak to fully address the problem, e.g., Oxford University’s Frankie Buckingham suggests that enhanced weathering would not work on its own . Many are just too expensive to implement at scale, such as space mirrors, global afforestation, global desert modification, and global ocean fertilization . Large-scale afforestation, for example, could cost up to 393 billion USD per year in order to abate 6.0 gigatonnes of carbon dioxide per year by 2055, which would only result in “10% of the level of mitigation needed to limit global warming to 1.5 °C by … mid-century” . In the end of the elimination process, the study found only three technologies could be considered highly efficient and not too costly: stratospheric particle injection, marine cloud brightening, and large-scale direct air capture .
II. Socio-Political Effects
Cost-effectiveness is important, but it isn’t the only thing governments should consider when engineering the climate. They must also consider the socio-political consequences of any implementations. Governments must consider two big questions:
- Where are these technologies going to be implemented?
- Who experiences the side effects of these technologies?
Let’s look at the first question. When considering where to implement a technology, governments must first consider whether a technology could be centrally implemented. A centralized implementation is easier, requiring fewer involved parties. A decentralized implementation could become very complex – if many countries have to independently execute the technology, the coordination and unity between these independent executors could cause problems (although this is not necessarily the case – many examples, such as air traffic standards, international treaties for coordination, etc. exist to prove the contrary). For example, large-scale direct air capture would require a decentralized implementation, as multiple countries would have to engage in direct air capture independently. 
A technology could also be implemented in an international common space. A “common space” refers to places where no national sovereignty exists, such as international waters, Antarctica, non-territorial airspace, or outer space. Implementations in “common spaces” are problematic, as technically no one has claim to that area, and technologies in such spaces affect the use of that common space for everyone. Both marine cloud brightening (MCB) and stratospheric particle injection (specifically high-altitude SPI), while technically centrally implementable as only one country would have to execute the technology, would involve the use of common space.  Further, for these centrally-implementable technologies, the burden would be unequal. Countries with access to oceans would have to take on more cost and responsibilities as opposed to countries without such access.
Governments then have to add on the question of who experiences the side effects of these technologies. Relative to a country, there are two options: the country itself, or everyone (global). Global effects, obviously, are problematic socio-politically. If one country implements a technology to benefit itself, and that technology adversely affects others not involved, it will likely cause an international incident.
And so, the technologies that were earlier identified as both efficient and executable are also potentially problematic in the socio-political sphere. So it might seem that coming up with the perfect implementation seems impossible, or at least extremely difficult, perhaps requiring more cooperation than the world might be capable of. There are technologies that could be less problematic socio-politically, but if these technologies are very costly and/or not very effective, some countries will have to bite the bullet and use more of their resources on less-efficient techniques, assuming any countries would still be willing to implement those less-effective technologies at all.
Some studies attempt to create plans that would balance these issues. However, few add another important issue on top of all these concerns: the issue of ethics. Because an implementation can be socio-politically perfect, cost-effective, and efficient, but if it’s not ethical, should we implement it?
III. Ethical Analysis
The ethics of climate engineering is hard to assess, because depending on your personal ethics, you may have different opinions about whether climate engineering is acceptable. This is further complicated by the different technologies included in the climate engineering sphere that all have different ethical implementations.
To make the ethical discussion clearer, we can use the Markkula Center for Applied Ethics’ six lenses  on the two efficient and executable technologies identified: stratospheric particle injection and marine cloud brightening . Three lenses highly relevant to the implementation of climate engineering are the utilitarian lens, the common good lens, and the care ethics lens.
The utilitarian lens emphasizes achieving the greatest happiness for the greatest number . MCB and SPI technologies, although they may have some adverse side effects that could affect the utilitarian calculus, should, if functioning correctly, combat climate change on a global scale, and thus improve the climate for most of the world, both for people and the environment. Therefore, from the utilitarian perspective, use of these technologies would be ethical.
Similarly, the common good lens would likely also judge both technologies as ethical. Clean air, clean water, and a clean environment is a “common good” shared by all on Earth, and thus as both technologies aim to better the environment, they are ethical technologies.
However, the Care Ethics Lens may not see these technologies as necessarily “ethical”. Care ethics emphasizes how individuals and specific circumstances are important and does not prioritize following rules or calculating utility . And both of these technologies would also have adverse effects globally. Some people would suffer from these implementations. There would be floods in some places, droughts in others (and how these might vary from natural variation would raise questions of liability), and possibly (in the case of SPI) acid rain. If you use a person-focused ethic like care, which prioritizes the specific circumstances of people, these technologies might not be the most caring way of responding to climate change.
Realistically, the care ethics lens and the idea that any suffering caused by a technology makes said technology unethical makes many technological innovations look less inviting. Technological advancement often results in suffering, and suffering is ethically important. But the utilitarian and common good lenses again come to the forefront: What is more important? Preventing the possible future suffering of a few by not engineering the climate, or relieving the current suffering of much of the planet by using climate engineering technologies?
This is a question that will likely be asked continuously for the next few decades. However, as discussed above, there is yet to be a climate engineering technology that could be considered viable. But at the rate the field is advancing and our climate is warming, it may be a question that becomes more and more important very soon. Because even if we manage to find a solution that is affordable, quick, centralized, and also somehow socio-politically acceptable, would it be right to alter the climate and deliberately cause some people’s lives to worsen so that the planet can heal?
 Brad Zukeran and Shivani Dharanipragada, “A Brief Introduction to Climate Engineering,” Markkula Center website, August 2023.
 National Academies of Sciences, Engineering, and Medicine. “Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance.” Washington, DC: The National Academies Press, 2021.
 Zürn, M. and Schäfer, S. “The Paradox of Climate Engineering.” Global Policy, 4 (2013): 266-277.
 Edelmann, B., & Menker, C. “Enhanced weathering: When climate research takes unexpected turns.” Medill Reports Chicago. December 2, 2021.
 Austin, K.G., Baker, J.S., Sohngen, B.L. et al. The economic costs of planting, preserving, and managing the world’s forests to mitigate climate change. Nature Communications 11, 5946 (2020).
 Markkula Center for Applied Ethics. “A framework for ethical decision making.” Markkula Center website, November 8, 2021.