"Unleashing the Power of the Sun: Is Sunlight Reflection the Key to Cool Our Planet?"

Unleashing the Power of the Sun: Is Sunlight Reflection the Key to Cool Our Planet?



The eruption of Mount Pinatubo in the Philippines in 1991 was one of the largest volcanic eruptions of the 20th century. Its ash plume rose above the atmosphere and spread a layer of aerosol particles across the globe, creating a solar umbrella that reflected sunlight and caused global temperatures to drop by almost half a degree Celsius for nearly two years. This phenomenon was not unique to Mount Pinatubo, as other large volcanic eruptions have also had a cooling effect on global temperatures.

Major volcanic eruptions such as El Chichón in 1982 have also caused significant drops in global temperatures by about half a degree Celsius, similar to other major eruptions in the past century. Today, scientists are investigating the possibility of replicating this phenomenon using a technology called solar geoengineering to combat global warming. Proponents argue that given the worsening effects of climate change, it is important to explore all potential solutions to alleviate suffering. However, opponents contend that the risks associated with this technology are too great and should not be considered as a viable response to global warming.

While technological advancements have undoubtedly brought about many benefits, there
are also inventions that some may wish had never been created. This raises an important question when it comes to solar geoengineering: should we be exploring this option? Given the high stakes of the survival of humanity on Earth, I interviewed a range of experts, including scientists, lawyers, and indigenous leaders, who hold strong opinions on both sides of the debate. Despite differing views, scientists agree that solar geoengineering has the potential to cool down the planet by reflecting sunlight away from the Earth and preventing heat from becoming trapped in the atmosphere. One approach involves injecting aerosols into the stratosphere, mimicking the effects of volcanic eruptions. This approach is currently the most commonly researched method.

Scientists are exploring various methods for solar geoengineering, including brightening marine clouds and deploying reflective shields in outer space. However, these technologies are still in the research phase and would require massive intervention in our complex climate system to achieve large-scale cooling effects. Solar geoengineering is supported by some scientists because we are currently on a concerning path with rising carbon dioxide emissions. While reducing emissions is essential in the long run, it is not sufficient to eliminate climate risk because the risk stems from accumulated emissions.

University of Chicago Professor David Keith argues that in order to mitigate the worsening impacts of climate change, we must move beyond just reducing emissions. Extreme weather has already resulted in a significant percentage of global deaths, and heat-related deaths are on the rise. Supporters suggest that we should explore climate processes, use computer modeling, and develop technologies to determine if and how we could safely deploy them globally, alongside other solutions. However, meddling with the global climate is a complicated issue as the whole system is interconnected. Adding new elements into our atmosphere or stratosphere could create unpredictable changes in the way the climate system responds and potentially exacerbate extreme weather events caused by climate change. Despite the risks, there is a need to understand the benefits and risks of solar geoengineering. Nevertheless, we cannot answer the most significant questions about the climate system response unless we undertake a full-scale deployment, which would require unprecedented global cooperation in terms of scale and time. Moreover, even if we stop emitting greenhouse gases, the warming effect of the carbon dioxide we have emitted since the industrial revolution will persist for thousands of years.

The proposed solar geoengineering techniques have a short lifetime in the atmosphere and require constant deployment for continued cooling effect, which poses an unprecedented burden on future generations to adhere to treaties and institutions for thousands of years. In case of an international disagreement, war, or sudden termination, the world could face rapid warming known as termination shock. Critics view solar geoengineering as ungovernable and unsustainable, given the unpredictability and drastic changes it might awaken in climate, weather, and biodiversity. Sweden's rejection of a solar geoengineering project in 2021 highlights concerns raised by environmental and indigenous groups. Most solar geoengineering research takes place in labs with models and simulations due to opposition like this, turning the debate into one about the extent of research. In January 2022, 400 scientists called for a non-use agreement on solar geoengineering

The proposed solar geoengineering techniques have a short atmospheric lifespan, which means they would need to be continuously deployed for centuries to have a long-term cooling effect. This would require future institutions and treaties that can be upheld for thousands of years, an unprecedented burden on future generations. In the event of war, global depression, or sudden termination of solar geoengineering, rapid warming, also known as termination shock, could occur, posing a significant risk to the planet. Despite the opposition from environmental and indigenous groups, some scientists are in favor of low-risk research, such as fundamental climate processes, computer simulations, and modeling. However, research that develops technology leading to full-scale deployment is opposed by many scientists, as they fear it could be ungovernable and unsustainable. Some scientists call for a robust international scientific assessment that includes experiments to advance solar geoengineering technology. Still, they stress that research does not imply support for its use and that we cannot prevent future generations from using the technology.

I spoke with Sarah Doherty, a researcher at the University of Washington who studies marine cloud brightening, about the significance of ongoing research in this area. According to her, it is crucial to conduct this research now to make informed and equitable decisions in the future, as the knowledge about these options is already widespread. Some advocate for immediate deployment of these technologies, indicating the likelihood of their use in the future. However, both sides agree that solar geoengineering could negatively impact efforts to reduce carbon emissions, as it may serve as an excuse for continued fossil fuel use. While there is a political concern that these technologies may be exploited, it should not serve as an ethical basis to restrict potentially risk-reducing research. Mexico is currently the only country that has banned solar geoengineering experiments, whereas the US is developing a research plan in this area. Climate-focused global organizations are now conducting assessments and issuing recommendations, but there is no clear consensus on the path forward. Despite this, everyone I spoke to on both sides of the issue is deeply invested in preserving our planet's future. The tension between opposing views can lead to more thoughtful and rigorous solutions to the problems we face. For instance, volcanic eruptions like Mount Pinatubo's in 1991 have shown that aerosol particles in the stratosphere can lower global temperatures by half a degree Celsius for almost two years, as was the case with other eruptions in the past century.

Scientists have been investigating the possibility of replicating the cooling effects of massive volcanic eruptions through solar geoengineering, a technology that some believe could help mitigate the impacts of global warming. While some see solar geoengineering as a valuable tool in the fight against climate change, others argue that its potential risks outweigh its benefits. The benefits and risks of solar geoengineering were explored by speaking with scientists, lawyers, and indigenous leaders who hold opposing views on the matter. While solar geoengineering could potentially cool the planet by reflecting sunlight away from Earth through the injection of aerosols into the stratosphere or brightening marine clouds, its large-scale deployment could interfere with the complex climate system and lead to unintended consequences. Nevertheless, some scientists argue that we must explore solar geoengineering as we currently face a dire situation with rising emissions and continued climate change impacts, which could worsen even if emissions are cut to zero.

According to a recent study, extreme weather is responsible for almost 10% of global deaths, with an increase in heat-related deaths. Supporters of mitigating these effects argue that we need to explore climate processes, use computer modeling, and develop technology to safely deploy solutions. However, solar geoengineering, which involves interfering with our global climate, is very complex and could create unpredictable changes in the way the climate system responds. Adding new elements to our atmosphere or stratosphere could worsen the extreme weather caused by climate change. Additionally, a full-scale deployment of solar geoengineering would require unprecedented global cooperation and commitment for thousands of years, which is a burden to put on future humanity. Critics argue that solar geoengineering is ungovernable and unsustainable due to the risk of rapid warming caused by termination shock. Opposition to solar geoengineering has led to most research taking place in labs with simulations, and in 2022, 400 scientists called for a non-use agreement on solar geoengineering. They supported low-risk research on fundamental climate processes that doesn't lead to deployment.

Critics of solar geoengineering are concerned that increased modeling could lead to full-scale deployment, but they admit that some simulations are useful and cannot be eliminated. They are opposed to research that could lead to technology development and deployment. However, some scientists support research into solar geoengineering, including experiments that could advance technology, but they do not support the use of the technology itself. They acknowledge that we cannot prevent people from using these technologies in the future, but we can make more informed and equitable decisions through research. Solar geoengineering could have negative impacts on decarbonization efforts and may be used as an excuse for continuing fossil fuel sales. However, restricting research based on political concerns is not an ethical approach. Mexico has banned solar geoengineering experiments, while the US is developing a research plan. Climate organizations are making assessments and recommendations, but there is no clear path forward. Both sides of the issue care deeply about the future of our planet, and the tension between them can lead to more thoughtful and rigorous solutions to our current environmental challenges.