Can Geoengineering Really Save Us From Climate Disaster?

In 2015, the nations of the world resolved in the Paris Agreement to keep the increase in the global average temperature to below 2°C above pre-industrial levels’ and to pursue efforts to limit warming to 1.5°C. Despite this goal, it is unlikely that the increase will remain below 2°C celsius, and it is almost certain that it won’t stay below 1.5 [1]. In order to help reach these long-term temperature goals, global action must be accelerated far beyond the current level, which will only be possible with a new type of technology, that is, geoengineering.

One of the most popular examples of geoengineering is solar radiation modification (SRM), which is an umbrella term for technology that aims to offset the effects of greenhouse gases by increasing the reflectivity of Earth in order to create a net cooling effect on the atmosphere [2].

Another popular geoengineering option includes greenhouse gas removal (GGR), in which we remove CO2 from the atmosphere and store it in natural, biological, or geological sinks [3]. This paper will seek to examine some of the most common methods of geoengineering, and will then examine the potential good, as well as the potential risk involved with these techniques in order to draw the conclusion that geoengineering is necessary for a sustainable future. 

What is Geoengineering?

The most common method of SRM is stratospheric aerosol injection (SAI). The basic idea involves injecting gases such as SO2 into the atmosphere that eventually turn into aerosols and increase the atmosphere’s efficiency in reflecting solar radiation back to space. Inspired by the cooling effects of large volcanic eruptions, the primary goal of SAI is to increase the albedo effect and reduce the amount of solar radiation that is absorbed into the atmosphere. Another less studied attempt to lower global warming is through that of cloud brightening (CB). The basic idea is to mitigate global warming by increasing the reflectivity of shallow low-level liquid clouds by manually increasing the number of water droplets in a given cloud. The primary motivation behind targeting clouds for SRM is because they scatter and reflect radiation coming to Earth’s surface, and they influence the emission of radiation into space (i.e. they emit greenhouse gases) [2].

Even if SRM is deployed to temporarily cool the planet, it is widely believed that carbon dioxide removal (CDR) will still be necessary to address the root cause of climate change, which is excess atmospheric CO2. This long-term solution would rely on GGR techniques, with one of the most prominent being direct air capture (DAC). DAC works by pulling CO2 directly from ambient air using chemical processes, where it binds to specially designed solvents or solid sorbents. Once captured, the CO2 is separated through heating or pressure changes and then compressed for permanent geological storage or potential reuse in industrial processes [4].

Benefits of Geoengineering

The primary benefit of SAI is that it will help to lower the effects of global warming and climate change [5] . Additionally, work is being done to make SAI more effective by primarily injecting absorbing aerosols into the upper stratosphere, which could significantly weaken the effect of greenhouse gases [6]. CB has also been found to be beneficial when applied to areas around the great barrier reef – particularly in smaller doses [7]. As demonstrated in figure 1, the injection of aerosols into the upper stratosphere would theoretically cause the number of surface temperature anomalies to decrease. 

 

Figure 1 from [6]: Amount of theoretical surface temperature anomalies after SAI implementation

GGR is also seen as necessary by many in order to achieve net zero emissions. SRM and GGR techniques are also seen as a great way to buy time until we can figure out a longer term solution. They will also theoretically help lower the global temperature increase to the goal of the Paris Agreement, which is less than 2 degrees celsius. One of the main reasons that achieving a 1.5 - 2 degree cooling threshold is so important, as demonstrated in figure 2, is that it will end up heavily reducing CO2 emissions, which will enable us to have a much more sustainable future [3]. 

Figure 2 from [3]: CO2 emissions if nothing is changed compared to warming below 2°C Celsius

The primary benefits of DAC are that it is easily quantifiable, and its effects are both immediate and permanent. This is preferred over methods like reforestation, which can take decades to show results, are hard to measure accurately, and risk being undone by events like wildfires [8]. Research is also being done to lower the cost of the ingredients used in DAC, which could increase its sustainability into the future [9].

Another beneficial GGR method is that of enhanced weathering (EW). The essential strategy is to amend farmland soils with crushed silicate rock, such as basalt. In contrast to other carbon dioxide removal (CDR) strategies, EW can improve food and soil security, and reduce ocean acidification. It is also easily rapidly scalable due to its utilization of current technology. It is therefore a promising strategic management option for atmospheric CDR [10]. 

Therefore, most of the benefits of geoengineering come in the form of delayed or even reversed climate change. SRM methods primarily benefit the world by immediately lowering the effects of climate change, and GGR methods benefit the world by helping to remove the cause of climate change. 

Drawbacks of Geoengineering

While beneficial in mitigating the effects of a climate change, geoengineering could end up having drawbacks that diminishing its usefulness. For instance, SAI could end up altering global weather patterns, as well as cause acid deposition and ozone changes. It could also end up being too effective, and cause unforeseen consequences due to global cooling [5]. Another major criticism of SRM techniques in particular is that they can be seen as a form of adaptation rather than mitigation, which is unsustainable in the long term because it fails to solve the root of the problem, and does not acknowledge the growing amount of greenhouse gases in the atmosphere. This causes many SRM techniques to not actually get closer to the goal set out by the Paris agreement. Additionally, many long-term solutions could take years, or even decades to come up with, and that kind of time is a luxury that is not guaranteed [3]. Another major criticism of SRM methods is that they do not address the growing problem of ocean acidification due to CO2, and some environmentalists speculate that it could even make it worse. SRM would also likely disrupt monsoon seasons, which is very important in deciding the fate of the seasonal yield of a particular crop [11]. Finally, there is no consensus as to whether or not SRM techniques are feasible and whether or not they will even be able to cool the earth in mass if deployed [12]. 

Despite the obvious benefits of GGR methods such as DAC, they come with some major drawbacks. The first of these is that DAC in particular is very hard to scale up due to the relatively low amount of CO2 in the air (about 0.04 percent). As a result, upscaling the current technology to have the ability to remove a substantial amount of CO2 will be extremely costly in both time and money. The second detriment to DAC is that it must consume vast amounts of energy: about 1.2 megawatt hours per ton of CO2 removed. The third cost of DAC is that it requires some specific environmental conditions to operate in a given area–those being the right amount of humidity and temperature, as well as needing a vast amount of land to operate [8] . 

Therefore, most of the detriments of geoengineering come in the form of uncertainty regarding its sustainability, cost and effectiveness. SRM techniques are primarily criticized for their uncertain effects, and GGR methods are primarily criticized for their questionable scalability. 

Conclusions and Steps Forward

Based on the presented evidence, geoengineering is necessary for the construction of a more sustainable future. Despite the many drawbacks and controversy associated with geoengineering, it should still be sought out because of the bleak situation that humanity will be in if they do not decide to pursue it. Most of the drawbacks of geoengineering are that the long term effects are unknown, along with questions of scalability. However, the long-term effects of deciding to abstain from geoengineering, that is, continuing to let climate change run rampant are rising sea levels, ocean acidification, flooding, agricultural disruption, etc, and have been well known for decades, and are not particularly desirable [13]. Therefore, the worst case scenario for implementing geoengineering is equivalent to the current trajectory for failing to implement geoengineering. 

If humanity fails to continue research and implementation of geoengineering, the effects of climate change will continue to grow unchecked, and could end up proving catastrophic. Even if the effects and scalability of geoengineering are uncertain, we must try, if for no other reason than to know for sure that these methods don’t work. If we don’t at least look into the situation, the climate change catastrophe will only grow worse, and a solution may be too long delayed to do any good.

References

[1] P. Irvine, D. Keith, and A. Moore, “Towards a comprehensive climate impacts assessment of solar geoengineering,” Proc. R. Soc. A Math. Phys. Eng. Sci., vol. 475, no. 2229, p. 20190255, Nov. 2019. [Online]. Available: https://royalsocietypublishing.org/doi/10.1098/rspa.2019.0255

[2] European Scientific Advice Mechanism, “Solar Radiation Modification: A scientific review on efficacy, risks and governance,” Scientific Advice to Policy by European Academies, Mar. 2023. [Online]. Available: https://scientificadvice.eu/scientific-outputs/solar-radiation-modification-evidence-review-report/

[3] C. Schäfer, J. Low, D. Irvine, and J. Rickels, “Solar geoengineering: Risk–risk trade‐offs in the context of a stakeholder‐informed governance framework,” Global Transitions, vol. 3, pp. 138–151, Sep. 2021. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S2211467X21000420

[4] C. Müller, D. W. Keith, and J. A. Dykema, “Liquid solvent direct air capture’s cost and carbon dioxide removal performance,” Commun. Earth Environ., vol. 5, no. 1, p. 38, Jan. 2024. [Online]. Available: https://www.nature.com/articles/s43247-024-01773-1

[5] J. Proctor, D. Callaway, K. Ricke, M. Wei, and D. Cullenward, “A risk–risk analysis framework for solar geoengineering,” Oxford Open Climate Change, vol. 5, no. 1, kgaf012, 2024. [Online]. Available: https://academic.oup.com/oocc/article/5/1/kgaf012/8089845

[6] S. He, B. J. Soden, G. A. Vecchi, and Y. Yang, “Stratospheric aerosol injection can weaken the carbon dioxide greenhouse effect,” Commun. Earth Environ., vol. 6, no. 1, p. 89, May 2025. [Online]. Available: https://www.nature.com/articles/s43247-025-02466-z

[7] M. Greshko, “Coral reef cloud brightening moves from lab to ocean,” WIRED, Jun. 2023. [Online]. Available: https://www.wired.com/story/coral-reef-cloud-brightnening-australia

[8] D. Chandler, “Reality check on technologies to remove carbon dioxide from the air,” MIT News, Nov. 20, 2024. [Online]. Available: https://news.mit.edu/2024/reality-check-tech-to-remove-carbon-dioxide-from-air-1120

[9] R. Vincent, P. Tarantino, and A. Gupta, “Accounting for carbon capture solvent cost and energy demand in the energy system,” arXiv preprint, arXiv:2411.09520, Nov. 2024. [Online]. Available: https://arxiv.org/pdf/2411.09520

[10] D. J. Beerling et al., “Enhanced weathering in the U.S. Corn Belt delivers carbon removal with agronomic benefits,” arXiv preprint, arXiv:2307.05343, Jul. 2023. [Online]. Available: https://arxiv.org/abs/2307.05343

[11] Climate Analytics, “Why geoengineering is not a solution to the climate problem,” May 2018. [Online]. Available: https://climateanalytics.org/publications/why-geoengineering-is-not-a-solution-to-the-climate-problem

[12] Congressional Research Service, “Climate Intervention: Geoengineering and stratospheric aerosol injection,” R47551, May 24, 2023. [Online]. Available: https://www.congress.gov/crs-product/R47551

[13] U.S. Geological Survey (USGS), “What are the long-term effects of climate change?” [Online]. Available: https://www.usgs.gov/faqs/what-are-long-term-effects-climate-change