The Role of Solar Geoengineering as Climate-Regulating Technology
Executive Summary
Greenhouse gasses, which are responsible for temperature increases associated with global warming, are reaching alarming levels. Despite the general awareness of this issue, emissions are steadily rising each year as the global economy continues to grow. Currently, the level of mitigation measures needed to create significant results in the fight against climate change are too costly for economies to withstand. There must be another solution to this pressing global catastrophe, right? Fortunately, solar geoengineering, which controls temperatures through the manipulation of sunlight, may be a way to limit the damages of global warming without reducing emissions. A variety of different solar geoengineering strategies each have unique benefits and risks. Therefore, geoengineering is needed in order to prevent irreversible environmental damage from climate change, but should be restricted to limited use. The best practice for solar geoengineering is increased research along with strong regulations and governance to prevent misuse.
Introduction
In response to threats posed by GHG emissions, researchers are developing renewable technologies, integrating cleaner energy sources into the energy grid, and inventing new sustainable technologies. These techniques to reduce emissions are referred to as mitigation. However, mitigation efforts continue to be extremely insufficient after nearly 30 years of internationally coordinated efforts. For instance, in 2021, energy related global carbon dioxide emissions rose by 6 percent. That year approximately 36.3 billion tonnes of carbon dioxide were emitted which was the highest level ever recorded (IEA, 2022). While this drastic increase is partly due to the revitalization of the global economy after the COVID-19 pandemic, it fails to negate the severity of the carbon emission issue. While some minor improvements are being made to try to shift to renewable energy, the world is still far off pace for the level that scientists demand. Roughly 350 parts per million (ppm) of carbon dioxide is considered a safe level. However, the most recent estimates show approximately 419 ppm of CO2 in the atmosphere. Furthermore, global temperatures are predicted to rise by 2.7 degrees fahrenheit by the end of the century, but depending on levels of abatement, an increase of 8.6 degrees fahrenheit is possible (EPA).
The scope of Greenhouse gas emissions impacts are especially concerning, harming entire ecosystems. For example, the warming of the Earth’s atmosphere is causing ocean acidification which kills coral reefs; a fundamental aspect of marine life health. While coral reefs only cover 1 percent of the sea floor, they are responsible for supporting approximately 25 percent of marine life (MacPherson, 2010). The destruction of reefs illustrates the ability of anthropogenic emissions to severely impact unrelated areas of the globe. As emissions continue to rise to new record breaking levels, the Earth will continue to lose biodiversity and critical ecosystem services.
Solar Geoengineering Methods
Recently, scientists and engineers have proposed a new solution to the current global warming crisis through a process called solar geoengineering or solar radiation management (SRM). The concept of solar geoengineering has existed since the 1960s, but the inability to reduce emissions and near critical warming thresholds has generated interest in solar geoengineering development. Despite the fact that these climate geoengineering technologies are controversial and widely untested, more researchers are enthusiastic about increasing research in SRM and its implementation in the near future. Solar geoengineering can be simply described as an attempt to bring down global temperatures by redirecting sunlight away from the Earth’s atmosphere or allowing more heat to escape into space. Essentially, solar geoengineering is the manipulation of the atmosphere in order to decrease global average temperatures. Solar Geoengineering is unique compared to most other climate regulating strategies because it does not aim to reduce greenhouse gas emissions.
There have been many different solar geoengineering strategies that have been proposed. The six most common are aerosol injection, marine cloud brightening, high-albedo crops and buildings, ocean mirror, cloud thinning, and Space sunshades (Dunne, 2018).
Aerosol injection
Aerosol injection at high altitudes in the stratosphere is currently the most popular form of all solar geoengineering methods. This process “maintains a layer of reflective particles in the upper atmosphere” via a modified aircraft (Low et al, 2022). Aerosol Injection mimics the natural cooling effects of volcanic eruptions. Volcanic eruptions cool the Earth by releasing sulfur gasses that reflect light from entering Earth’s atmosphere. According to Dr. Anthony Jones, after the Mount Pinatubo eruption in 1991, “there was a global cooling of about half a degrees for two or three years afterwards, so it does seem that injecting aerosols into the stratosphere is quite effective” (Dunne, 2018). The cooling effect of volcanic eruptions to global temperatures gives optimism that this phenomena can be recreated by humans to combat the temperature rise associated with global warming. Proponents of aerosol injection argue that the cost is relatively cheap and would cause little to almost no impact on the current economy. According to a Harvard Study in 2018, aerosol injection could have a big planetary cooling effect for a relatively small price tag of “around $2.25 billion a year over a 15-year period” (Paddison, 2023). In the short term, aerosol injection is a cost effective and efficient method that quickly provides protection from increasing temperatures.
Marine Cloud Brightening
Marine Cloud Brightening Another SRM technique that is also gaining popularity. Brightening clouds over the ocean would reflect more light away from entering Earth’s atmosphere. Currently, researchers theorize that spraying saltwater into the clouds is a possible way to achieve brighter clouds (Low et. al, 2022). More specifically, the salt particles would “act as “cloud condensation nuclei”, meaning they would facilitate the condensation of water vapor into liquid. As more water droplets are created, clouds would appear larger and brighter” (Dunne, 2018).
High-Albedo Crops and Buildings
High-albedo crops and building is the least controversial geoengineering strategy, but also is unlikely to result in significant reduction in global temperatures. Therefore, high-albedo crops and buildings would have to be used in conjunction with other SRM methods. Painting buildings white and genetically engineering plants to have more reflective surfaces are two ways to create a small cooling effect. White building would especially be effective in cities because “it could potentially help reduce the highest temperatures to reduce health problems for the population during heatwaves” (Dunne, 2018).
Ocean Mirror
A less well-known option for minimizing the effect of sunlight on would be to use the ocean as a giant mirror by seafoam. This foam would be created by sea vessels churning up “millions of tiny microbubbles on the ocean surface” and can be “ten times higher than the ocean itself” (Dunne, 2018). Since the ocean covers the majority of the Earth’s surface, ocean seafoam has potential to reflect a substantial amount of incoming sunlight.
Cloud Thinning
The removal of cirrus clouds, also known as cloud thinning, is another hypothetical technique that would reduce the impacts of sunlight. Cirrus clouds are thin, high altitude clouds composed of tiny ice crystals. While Cirrus clouds do reflect a small amount of sunlight back into the atmosphere, the clouds also “absorb large amounts of long-wave radiation” (Dunne, 2018). Therefore, cirrus clouds have a net warming effect on the planet. In fact, the heat trapping effects of cirrus clouds outweighs the warming effect of all human-released carbon dioxide.
Space Sunshades
The last SRM strategy discussed by scientists is sending mirrors into Earth’s orbit. This technology is viewed as the least environmentally threatening because the mirrors would be implemented in space. These sunshades would reflect sunlight from reaching Earth’s atmosphere. The size of the mirror would regulate the amount of sunlight reflected back into space and the overall cooling effect of the mirror on Earth. Also, the amount of sunlight reflected needed to create a significant impact is relatively small. According to Professor Govindasamy Bala, “Approximately a 2% reduction in incoming sunlight [using a sunshade] is sufficient to offset the warming from a doubling of CO2 from the pre-industrial level of 280 ppm to 560 ppm. (Dunne, 2018)” Therefore, sun shades can be controlled to produce the desired level of temperature reduction.
The Controversy Behind Solar Geoengineering
There are many uncertainties and concerns with solar geoengineering from the lack of testing and research in the area. A negative aspect of solar engineering is that “solar geoengineering at planetary scale is not governable in a globally inclusive and just manner within the current international political system” (Biermann et. al). In order for this concept to work it would require a level of international cooperation and that has not been seen. Global warming disportportionatelty impacts countries, therefore, the optimal use of SRM technology will be different for each country. Additionally, solar geoengineering strategies such as aerosol injection can have impacts in specific regions. For example, aerosol injections to limit global warming to 1.5 degrees celsius reduces the fire risk for most of the globe. However, regions in the United States and northeast Asia would actually see an increase in fire risk if the technology was implemented on a global scale (Burton et. al, 2018). Similarly, Marine Cloud Brightening at significant levels has detrimental impacts on a global scale. The overuse of this technique is forecasted to change precipitation levels across the globe. More specifically, widespread use of Marine Cloud Brightening would decrease precipitation over a large area of Amazonia and Nordeste regions, “with reductions amounting to more than 50% in places” (Jones et al., 2009). While geoengineering strategies are expected to be effective at reducing temperatures, the consequences are deterring implementation. Furthermore, there are many uncertainties with solar engineering such as potential damage to the ozone layer, unknown impact to vegetation, and loss of biodiversity. Also, aerosol particles only remain in the atmosphere for about a year and would have to be regularly maintained (Weisenstein et al.). Therefore, the cost of the solar geoengineering projects and constant management would not be economically efficient in the long run. Seafoam is another example that would be costly long term because in order to create ocean mirroring conditions would have to be continually sustained for multiple days and even weeks to be effective.
Principles of SRM Use and Governance
The controversy surrounding solar geoengineering and further anthropogenic manipulation of the environment remains a serious topic of debate. However, global emissions are spiraling out of control and mitigation efforts have been largely ineffective. This is largely due to the fact that economies would be crippled by the cost of mitigation needed in order to save the planet. Renewable energy, technology such as electric cars, and international emission standards have been the center of the mitigation approach. Since carbon emissions continue to grow each year and as the deadline to prevent irreversible climate damage to the Earth nears, it is imperative that an effective policy for controlling GHGs is implemented. Although, it is necessary that mitigation strategies continue to be developed and improved because solar geoengineering is not the permanent solution. Therefore, it appears that the use of solar geoengineering is inevitable in preventing the harmful effects associated with global warming.
According to the figure below, BAU stands for business as usual and no emission reduction efforts. In this case, global temperatures would increase by five degrees celsius. On the other hand, the use of SRM technologies has the ability to limit warming to 1.5 degrees celsius and would meet the goals of the Paris Agreement from 2015. However, because solar geoengineering techniques will have negative impacts on the environment, the best strategy is to use SRM along with mitigation and carbon dioxide removal. The question is not if, but when and how these technologies will be utilized and regulated.
Recently, Solar Geoengineering has gained more attention from scientists, researchers and governments as the implementation of SRM technology is becoming increasingly important in order to prevent devastating temperature increases. Until 2018, total global funding for solar geoengineering remained extremely low. For example, the Geoengineering Research Evaluation Act of 2017 called for “advancing understanding of albedo modification strategies that involve atmospheric interventions, such as cloud modification” (Congress.gov, 2018). However, the Geoengineering
Research Evaluation Act has not made any progress to being approved and instead has been referred to a smaller committee within congress. This shows how the United States government is not prioritizing research into SRM technologies and the progress needed to be made before SRM use. However, in the last three years, NOAA has invested approximately $22 million to projects related to geoengineering (Temple, 2022). Hopefully, this signals that more resources are directed towards solar geoengineering research and development so that these technologies are effective and safe.Since the effects of solar geoengineering techniques are unknown, it is imperative that more testing and research must be conducted before being implemented on a large scale.
Even though SRM strategies are an attractive solution to ending global warming concerns, these technologies cannot be seen as a permanent fix. Instead SRM should be used along with other mitigation efforts and carbon dioxide removal. Solar geoengineering gives reasons for people to keep polluting instead of solving the root of the issue. Businesses in particular will take advantage of solar geoengineering by prioritizing profit over finding ways to become more sustainable and produce less emissions. Having a high level of dependence on solar geoengineering for the prevention of global warming allows for the perpetuation of unsustainable levels of emissions (Umwelt Bundesmat, 2019). Eventually, society will need to function without any or very little emissions and solar geoengineering acts as a distraction to real progress. Additionally, the continual use of SRM methods is likely to interfere with natural global systems and have unanticipated environmental ramifications. For instance, aerosol injections could alter existing rainfall patterns and seafoam could be harmful to marine primary producers. These impacts need to be taken seriously because they could disrupt entire ecosystems.
The final requirement for the implementation of solar geoengineering is the presence of strong governance. There must be strong international cooperation and agreements so there is no misuse. Recently, international relations have become more fragile, but SRM technology requires responsible action. Furthermore, disagreements over solar geoengineering could cause even more unstable international relations. Since countries will want different levels of SRM use, it is imperative that clear solar geoengineering standards are established and followed.
References
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