Solar Engineering may be able to reduce global temperatures, but Sci&Tech Editor Georgia Brooks argues that the risks outweigh the benefits.
Solar Geoengineering refers to a currently largely theoretical approach to mitigating the effects of climate change, by artificially changing the climate systems of the earth and reflecting some incoming solar radiation back into space. It is an example of an approach to climate change that treats the symptoms of the problem rather than the root cause (i.e. greenhouse gas emissions) and is highly disputed and uncertain, but some believe that these kinds of radical measures are necessary.
How does Solar Geoengineering Work?
There are two main approaches to solar geoengineering currently being investigated: Stratospheric Aerosol Injection (SAI) and Marine Cloud Brightening (MCB). SAI involves injecting aerosols (tiny reflective particles) into the upper atmosphere, which mimics the cooling effect that can occur when major volcanic eruptions take place, as the particles reflect radiation back into space. However, this would not only have effects on global temperatures, but also on other climatic phenomena such as precipitation patterns.
MCB proposes spraying large amounts of particles such as sea salt aerosols into lower lying marine clouds. In theory, this creates brighter clouds as condensation occurs around the aerosols, also reflecting radiation and cooling the atmosphere.
What are the prospects?
Currently, very little practical research has been carried out to investigate solar geoengineering. The investigations that have taken place so far have generally involved computer modelling and current observations, but they do clearly show an overall reduction in atmospheric temperatures. To be able to reach the goal of limiting global temperature rise promised in the Paris Agreement, some consider that this could be the only means.
And the problems?
Solar geoengineering is generally a pretty unpopular approach, and for good reason. First and foremost, as mentioned above, solar geoengineering doesn’t address the root problems that are causing climate change: greenhouse gas emissions and a global culture of overconsumption. As such, it doesn’t solve any of the other associated problems, such as ocean acidification, and also could discourage solutions to or a decrease in our current emissions rates, creating an attitude of using symptomatic treatments for the problem, rather than changing harmful habits.
There are also huge uncertainties associated with solar geoengineering – apart from analysing volcanic eruptions of the past, we really have no idea how methods such as these could affect weather patterns and circulation, and the effects will be global, making it incredibly hard to carry out any sort of tests or experiments in this area.
This ties into the complicated geopolitical reality of methods such as solar geoengineering: because the atmosphere is global, the effects, for better or for worse, of using aerosols in this way would also be global. But additionally, for an approach like this to work, it would likely require the cooperation of at least the majority of the earth’s countries, something that current models do not reflect, but is important to consider. Rigorous governance is undoubtedly required if any sort of use is to go ahead.
So, is solar geoengineering the way forward?
It seems obvious that the risks of solar geoengineering hugely outweigh the potential benefits, particularly as any sort of comprehensive research would be so hard to carry out that the real effects of this method are likely to remain very uncertain. While some climate scientists argue that research should be carried out, as we currently do not know what the potential of solar geoengineering could be and it is important to establish this, this approach really misses the real problem that we are facing. Undoubtedly a symptomatic approach such as this could provide the possibility to slow global warming, at least temporarily, but it will also certainly create many more issues, without really addressing the root of the climate crisis.
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