In the face of sharply increasing global temperatures and the dire need to combat the current climate crisis, scientists and policymakers are exploring various innovative solutions. One of the most intriguing yet controversial methods gaining attention is solar radiation management. Here’s what it is and what it entails — and what the potential pros and cons of adopting this approach are.

What Is Solar Radiation Management?

Solar radiation management (SRM), also called solar geoengineering, is a term that actually refers to multiple forms of climate intervention which, theoretically, work to reduce global warming caused by greenhouse gasses. Unlike emissions reduction strategies, which focus on mitigating the root causes of the climate crisis, SRM attempts to modify the amount of solar energy that reaches the Earth’s surface, effectively offsetting some of the warming effects of greenhouse gasses.

Why Does Finding Viable SRM Methods Matter?

The primary motivation behind exploring SRM is its potential to counteract the rapid increase in global temperatures. As emissions continue to rise, the world may face dire consequences, including extreme weather events, rising sea levels, and ecological disruptions. SRM, if successfully implemented, could offer a rapid and relatively low-cost method of reducing the immediate impacts of the climate crisis.   It’s important to note that no form of SRM can replace the imperative need to reduce carbon and greenhouse gas emissions in the first place. However, it may be worthwhile to combine SRM with emission-reducing practices.   Effectively, SRM could provide a ‘safety valve’ in case emissions reduction efforts prove insufficient in limiting global warming to safe levels. Proponents argue that in combination with emission reductions, SRM could serve as a useful tool to achieve climate stabilization targets and prevent catastrophic climate scenarios. 

What Kinds of SRM Methods Are Available (and What Do They Involve)?

There are multiple proposed SRM techniques, which generally include the following:

• Space-based Geoengineering
• Stratospheric aerosol injection
• Surface albedo modification
• Ocean albedo modification
• Marine cloud brightening

Space-based Geoengineering

Space-based geoengineering involves the use of space-based devices to reflect or block sunlight, thereby reducing the amount of solar energy reaching the Earth. This approach aims to counteract global warming and mitigate climate crisis effects.   One possible method of space-based solar geoengineering is creating a sunshield positioned close to the first Sun-Earth Lagrangian equilibrium point (L1), about 1.5 million kilometers sunwards of Earth. The shield could intercept a percentage of sunlight headed for Earth, effectively reducing the radiative force of greenhouse gasses. It could be designed using high-tech, low-mass scattering structures or low-tech, high-mass scatters constructed in space using local resources. Some proposals even include using dust created from asteroids to create a sunshield.   Pros:  By reflecting or blocking sunlight from space, space-based geoengineering could effectively reduce the amount of solar energy reaching Earth, helping to counteract global warming. Unlike some localized geoengineering methods, space-based approaches could also have a global impact. Finally, being deployed in space, such approaches might be less likely to interfere with Earth’s weather patterns and ecosystems.   Cons: The technology required for space-based geoengineering is highly complex and not yet fully developed. The cost of developing, launching, and maintaining space-based systems would likely be prohibitively high, while its long-term effects on Earth’s climate system are uncertain. This method of SRM could lead to unforeseen changes in weather patterns. Further,  decisions about deploying space-based geoengineering could lead to political and ethical conflicts.

Stratospheric Aerosol Injection

Stratospheric aerosol injection (SAI) involves the intentional introduction of aerosols into the stratosphere to create a cooling effect through global dimming and increased albedo (ability to reflect light away from the earth). This method mimics the natural cooling effect that occurs after large volcanic eruptions, when particles released in the stratosphere reflect sunlight.   SAI could be implemented using various materials, including sulfur compounds, alumina, calcite, and salt, with sulfate being the most researched aerosol. The leading proposed method of delivery is custom aircraft, although other mechanisms are under consideration.    Pros: SAI may offer temporary albedo effects that can mitigate the amount of sunlight that reaches Earth, thereby intervening in the greenhouse effect. It could counter most changes to temperature and precipitation and take effect rapidly at low direct implementation costs.   Cons: SAI is widely acknowledged as the most-researched solar geoengineering method, but its implementation would require careful consideration of various factors and potential side effects. Concerns include imperfect control of the climate effects, potential negative impacts on ecology, political conflict, and unknown consequences on global health and quality of life. 

Surface Albedo Modification

Surface albedo modification is a theoretical solar geoengineering technique that aims to reflect more sunlight back to space by enhancing Earth’s albedo — the measure of sunlight reflected off the Earth’s surface — by modifying land or land-based structures. The proposals for albedo modification are diverse and include growing crops that reflect more light, clearing boreal forests in snow-covered areas, covering large desert or ice areas with reflective materials, and whitening mountaintops and roofs with white paint.    Essentially, the goal is to create large surfaces with a higher albedo, reflecting more solar radiation and thus theoretically reducing the temperature of the atmosphere.    Pros: This method could increase the amount of solar radiation reflected away from the Earth’s surface.   Cons: Surface albedo modification would not reduce the concentration of greenhouse gasses in the atmosphere. Moreover, there could be unwanted side effects on ecosystems, fauna, flora, and human communities that depend on those ecosystems.

Ocean Albedo Modification

Like land-based albedo modification, ocean albedo modification aims to increase the reflectivity of the ocean’s surface. This is typically achieved by creating microbubbles or using reflective materials on the water’s surface.    Pros: By increasing the ocean’s albedo, more sunlight is reflected back into space, rather than being absorbed by the ocean. This can help to reduce global warming by lowering the Earth’s overall temperature.   Cons: Ocean albedo modification is still in the experimental stage and involves complex processes and potential ecological impacts that need to be carefully studied and understood. It represents a novel approach to climate crisis mitigation, but requires further research to assess its feasibility, effectiveness, and potential side effects.

Marine Cloud Brightening

Marine cloud brightening works to increase the reflectivity of clouds over the ocean. By spraying fine droplets of seawater into the atmosphere, the method seeks to create or enhance cloud condensation nuclei, leading to the formation of brighter, more reflective clouds. These clouds would then reflect more sunlight back into space, reducing the amount of solar energy that reaches the Earth’s surface.    Pros: Marine cloud brightening may offer an effective organic form of solar radiation management.   Cons: This concept has been proposed and studied in theoretical and modeling contexts, but currently, it remains largely untested in the real world, and its potential impacts on weather patterns and ecosystems are not fully understood.

Help Address the Climate Crisis With Arctic Ice Project

Arctic Ice Project’s efforts are crucial to the protection of Arctic sea ice. Our team is developing reflective materials and strategies to increase the albedo of this precious ice, mimicking natural processes to reflect solar energy out of our atmosphere and restore the Arctic.   You can do your part in this critical fight by spreading awareness of and supporting efforts to mitigate the climate crisis. One way to do this is by donating to a climate restoration nonprofit like Arctic Ice Project. No donation is too small, though if you are not able to make a financial contribution, you can also share the message and inspire others to act through social media and by staying informed on climate projects.   Please consider donating to Arctic Ice Project today!