With warnings of rising planetary temperatures and the international community’s failure to implement preventative policies to combat climate change, the importance of developing technological solutions like solar geoengineering has increased. Solar geoengineering aims to reduce global temperatures by modifying solar radiation (SRM) or by decreasing atmospheric carbon dioxide through capture and storage in oceans or on land (CDR). In the absence of a genuine commitment to reducing emissions, scientists propose solar geoengineering as a last-ditch effort to tackle global warming.
In this context, a recent report by the French Defense and Climate Observatory highlighted the developments in the widespread deployment of solar geoengineering technologies in the coming decades, the associated natural and human risks, key actors, and the role of major powers in this field. The report also presented potential scenarios and recommendations for deploying these technologies by 2050.
Nature of Technologies and Risks:
Solar geoengineering, or solar radiation management (SRM), involves techniques designed to reflect sunlight to cool the Earth through large-scale, deliberate intervention in the Earth’s climate system to mitigate the harmful effects of global warming. However, using these techniques involves both human and natural risks. Several types of SRM technologies are designed, including:
Local Solar Geoengineering: Two local techniques have been developed: marine cloud brightening (MCB) and cloud thinning (CCT). Marine cloud brightening involves injecting tiny droplets into marine clouds to make them brighter and more reflective by spraying sea salt into low marine clouds. Brighter clouds help reduce the amount of solar radiation reaching the Earth’s surface, thereby lowering atmospheric and ocean temperatures.
Planetary Solar Geoengineering: This involves injecting aerosols into the stratosphere (SAI) on a planetary scale. This method disperses reflective particles via aircraft or balloons in the stratosphere, targeting the release of sulfate particles to reduce the amount of sunlight reaching the Earth and the heat trapped in the atmosphere. This approach aims to create cooling conditions similar to those following major volcanic eruptions. While this technique is the most studied for modifying radiative balance, it is also the most controversial due to its planetary scope and associated scientific uncertainties.
Space-Based Solar Geoengineering: Some solar geoengineering projects plan to deploy reflective devices (mirrors) in outer space to reflect about 2% of sunlight. This technique is less advanced and less studied due to its complexity and high costs, estimated in billions of dollars. Mirrors would need to be launched by rocket and positioned about 1,500,000 kilometers from Earth at the “Lagrange L1” point, where Earth’s gravity counterbalances the Sun’s gravity, allowing objects to be stable in orbit.
According to a 2023 United Nations report on solar geoengineering, the mirrors would last about 20 years. Currently, there is only one space-based geoengineering project, titled “Space Bubbles,” being carried out by a team from MIT, aimed at dispersing some sunlight away from Earth. However, it remains theoretical.
There are several natural risks associated with the three solar geoengineering techniques, including: persistent effects related to increased carbon dioxide levels, reduced photosynthesis affecting humidity, rainfall, and local oxygen concentrations (e.g., drought in South America, increased tropical rainfall), ozone layer degradation, increased hurricanes, and extreme climate changes with severe impacts on temperatures and ecosystems due to solar radiation.
Human risks include: reduced agricultural yields, decreased primary productivity in the Amazon, slight increases in rainfall disruption in Africa, health risks associated with temperature changes, declining air quality, and loss of ecosystem services (e.g., decreased photosynthesis).
Additionally, there is a common risk known as “social and technical lock-in,” where developed technologies become entrenched due to economic and political interests, making it difficult to reverse their deployment even if they prove ineffective or harmful, leading to what is known as “terminal shock.” This risk is particularly relevant for space mirrors, which might become targets in military conflicts, potentially causing an immediate increase in global temperatures. This risk also applies to geoengineering operations requiring ongoing chemical interventions.
Network of Actors:
The actors in the field of solar geoengineering vary between major countries, the scientific community, as well as the private sector, international bodies, and non-governmental organizations. However, major powers remain the most influential actors in the solar geoengineering network. Key players include:
United States: The country is the most advanced in solar geoengineering, dominating the sector through several major projects (such as Harvard, the University of California, Cornell). The Department of Defense is significantly involved, and the private sector has increasingly financed research, granting around $20 million from 2008 to 2018 for solar geoengineering initiatives and projects.
China: Active in solar geoengineering research, as evidenced by a publicly funded Chinese research project from 2015 to 2019. This project aims to study the climate impacts of solar geoengineering and explore related governance issues. In August 2020, China conducted a local solar geoengineering experiment on the Dagu Glacier in Sichuan to reduce glacier melting during summer.
Russia: Does not have a research program in solar geoengineering based on available information. However, the former Soviet Union had laid the groundwork for aerosol injection into the stratosphere, a proposal by researcher Budyko in the late 1970s. Moscow’s official stance appears supportive of solar geoengineering, as evidenced by its request to include a section on it as a potential climate change solution in the 2013 Intergovernmental Panel on Climate Change report and its acknowledgment of ongoing developments in geoengineering techniques.
Expected Scenarios:
Several scenarios are proposed for the future of solar geoengineering by 2050:
Scenario One: Unilateral Deployment by the United States: This scenario assumes that by 2047, the global average temperature will rise by +2.5°C compared to pre-industrial levels, with greenhouse gas emissions not sufficiently reduced and the international community failing to meet Paris Agreement goals. All countries will experience widespread natural disasters annually, resulting in thousands of casualties and displaced people, weakening the economic situation globally. In the U.S., political tensions rise, and the country becomes the world’s second superpower after China, starting from 2039. Additionally, drought and water scarcity severely impact agriculture, making cotton and corn cultivation impossible, and soybean and wheat yields drop by about 40% starting in 2025.
In this context, public criticism of the U.S. government increases for not adequately anticipating climate change impacts and delaying adaptation efforts. Consequently, in 2047, the U.S. officially announces the deployment of stratospheric aerosol injection, while it has not ratified the 2035 Solar Geoengineering Convention that prohibits unilateral technology deployment. This unilateral decision entrenches international polarization. With the UN and Security Council failing to resolve the crisis, Russia and China, along with a few partners, launch a diplomatic campaign condemning the “selfish” actions of the U.S., threatening military intervention, and initiating discussions within the alliance about counter-solar geoengineering operations.
Scenario Two: China and the “ArcticX” Project: This scenario posits that by 2050, global warming will reach +2.6°C compared to pre-industrial times. This will lead to the collapse of the Greenland ice sheet, the complete disappearance of winter ice in the Barents Sea, and the melting of summer ice in the Arctic, causing a two-meter rise in average sea levels, submerging thousands of homes, and leaving entire communities without habitable land. Biodiversity will also face consecutive extinctions, with thousands of plant and animal species disappearing since 2020. Additionally, conflicts over water and food resources, as well as social and environmental conflicts, will intensify.
In this context, an alliance of countries will form to deploy solar geoengineering technologies, with the U.S., China, and India leading, aiming to mitigate climate change impacts and calm rising social disturbances. After several proposals for deployment are rejected by the UN, China proposes a regional solar geoengineering initiative to protect the Arctic, announcing the “ArcticX” project in 2050, which aims to enhance the reflectivity of marine clouds over the Arctic.
This regional deployment receives support from all allied countries and most regional nations (such as Canada, Norway, Denmark, and Iceland), interested in protecting the poles. However, it faces opposition from Moscow, as melting ice caps in Greenland and the Barents Sea would allow Russia to use the Arctic as a commercial shipping route, rich in oil, natural gas, and minerals, and crucial fish resources. Consequently, Russia threatens to militarily attack the ships deployed by China.
Scenario Three: Solar Geoengineering as a New Consumer Commodity: In the first half of the 21st century, the Amazon rainforest gradually transforms into savanna, releasing increasing amounts of carbon dioxide into the atmosphere, surpassing an irreparable tipping point, resulting in a rise in the global average temperature to +3°C by 2037 compared to pre-industrial levels. Agricultural losses will affect 40% of global production. Consequently, technological advancements in carbon extraction from the atmosphere will face commercial and political failure due to ineffective technologies and social and environmental conflicts.
In this context, several countries (including the U.S., the U.K., Gulf States, Russia, and Maghreb countries), supported by oil lobby groups, will move towards deploying solar geoengineering. Europe will be divided, with Sweden, Norway, and Spain opposing any solar geoengineering deployment and implementing an emergency mitigation plan, while countries like France, Germany, and Italy will emphasize the need for urgent cooling measures. In 2037, oil lobby groups, backed by the U.S. and Gulf States, will develop a strategy to promote solar geoengineering to individual consumers, creating a new commercial market by promoting a new form of individual climate commitment. Meanwhile, several G77 countries, led by China, will strongly oppose these moves.
In conclusion, the French Ministry of Defense recommended integrating solar geoengineering as a political, geostrategic, and military tool, enhancing information exchange in this field, particularly through raising the issue in strategic bilateral dialogues, strengthening partnerships with atmospheric science research institutes (such as MétéoFrance), and integrating research on climate change impacts on natural systems and potential effects of solar geoengineering. The ministry also recommended establishing a scientific, technological, and geostrategic monitoring body to oversee the development of solar geoengineering projects and anticipate the ability of various actors to maintain technological leadership enabling unilateral large-scale deployment.
Source: Marine de Guglielmo Weber, et autres. (2023, Novembre). Géo-ingénierie solaire: enjeux géostratégiques et de défense. l’Observatoire Défense & Climat.
