In an open letter, more than 90 scientists from around the world urge further study into the possibility of enhancing solar radiation modification (SRM), which is the reflection of sunlight away from Earth’s atmosphere and is sometimes referred to as solar geoengineering, in order to reduce global warming and its effects.
According to CNBC, scientists do not support the approach because it could have significant negative effects, such as changing the planet’s systems in unexpected ways, and because it would not address the primary cause of climate change, which is the increase in fossil fuel emissions and their harmful effects on the environment.
Public health, economic security, and global stability are all at serious risk as a result of the disastrous effects that climate change is having on communities and ecosystems all over the world.
According to the letter, natural systems are getting close to points when catastrophic changes could occur, potentially accelerating climate change and having effects beyond what people can now adapt to.
The signatories of the letter, who include organizations including NASA, Columbia University, the Massachusetts Institute of Technology, and Harvard University, emphasize that cutting greenhouse gas emissions right away is the only way to permanently curb global warming, according to CNBC.
Despite the fact that cutting emissions is important, no amount of decrease can undo the warming effect of historical and current greenhouse gas emissions. According to the letter, the Earth is expected to keep warming for several decades under all of the climate change scenarios taken into account by the UN’s IPCC.
The Paris Agreement’s objective of reducing global warming to far below two degrees Celsius relative to pre-industrial levels, ideally below 1.5 degrees, will not be achieved, according to scientists.
It is becoming increasingly implausible that global warming will remain below 1.5–2 C in the near future, even with significant action to limit GHG emissions.
This is because, according to the letter, in order to reverse present warming trends, there must be a large decrease in atmospheric concentrations of greenhouse gases, which lag behind decreases in emissions due to their prolonged atmospheric lifetime.
Due to their interaction with clouds and ability to reflect sunlight away from the globe, some air pollution particles that people generally have been helping to slow down global warming.
In contrast to greenhouse gases, particle (aerosol) emissions from human activity can have a cooling effect on the climate. According to the letter, aerosols reduce climate by diffusing sunlight and, when mixed with clouds, can lengthen their longevity and improve their reflectivity.
The scientists continue by estimating that human-produced aerosols currently counteract around one-third of the warming caused by greenhouse gases.
Aerosol emissions have decreased while greenhouse gas emissions have increased due to controls on particulate air pollution.
Aerosols have an atmospheric lifetime of less than a week, so reducing aerosol emissions makes this source of climatic cooling disappear quickly. As a result, the scientists predicted in their letter that decreases in aerosol emissions over the next few decades will quickly reveal a sizeable but very speculative amount of global warming.
To keep warming below 1.5 degrees Celsius, technologies to remove atmospheric carbon dioxide are required, but they are too expensive and challenging to execute given the state of the climate system, the scientists said.
Recent scientific evaluations indicate that limiting near-term climate warming to around 1.5 C is unlikely without massive carbon dioxide removal from the atmosphere, based on analyses of a broad variety of realistic greenhouse gas and aerosol emission scenarios.
The authors concluded that employing carbon dioxide removal (CDR) at the scale required to considerably mitigate global warming presents enormous environmental, technical, and financial obstacles.
Physically, it may be possible to limit global warming to 1.5 degrees Celsius using CDR, but these difficulties and the slow response of the climate system make it unlikely that CDR could be implemented quickly enough or on a large enough scale to completely prevent dangerous levels of global warming in the near future.
Before things grow worse, scientists argue that it is imperative to examine these climate adaption technologies using already accessible techniques like small-scale field trials, analytical investigations, computer model simulations, and observations.
The use of SRM is not something we advocate, even if we completely support research into SRM methods. However, there are too many unknowns about how SRM deployment might affect the climate system to support its use.
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Indeed, the experts wrote, “We advocate a robust, expeditious scientific examination of the viability and consequences of SRM approaches especially because such knowledge is crucial to making effective and moral decisions about SRM adoption.
They noted that not enough is known about SRM at this time for it to be employed in a system of climate credits.
The experts stated in the letter that SRM is unlikely to ever be a viable candidate for an open market system of credits and independent actors because it does not address the origin of climate change or all of the repercussions of increased greenhouse gas concentrations.
The experts argued that in order to protect research findings from the effect of commercial interests, political pressure, and public pressure, climate danger must be independently assessed both with and without SRM.
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Governments, charities, and the scientific community should look for ways to increase the capacity of researchers in the Global South to conduct and direct SRM research, the scientists stated.
Testing methods to alter the climate, however, could impede efforts to create regulations for alternative techniques and divert attention from the urgent need to reduce greenhouse gas emissions, according to Lili Fuhr, deputy director of the Climate & Energy Program at the Center for International Environmental Law, as quoted by Inside Climate News.
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A report on geoengineering from a human rights viewpoint is now being worked on by a United Nations advisory committee to the Human Rights Council. According to Fuhr and Inside Climate News, some nations are developing a possible resolution on large-scale engineering for the U.N. General Assembly.
