Solar Radiation Management (SRM) in scientific circles can be a contentious topic. One general conclusion often made is that SRM is not a replacement for greenhouse gas mitigation.
A new research paper, published in the peer-reviewed journal Nature[1], has cast doubt on the benefit of SRM. The researchers studied the impact of sulphur aerosol release from two volcanic eruptions at El Chichón in Mexico in 1982 and at Mount Pinatubo in the Philippines in 1991. Both eruptions caused large quantities of sulphate particles to enter the stratosphere. The effect of the sulphur particles was to create a "veil" which reduced the amount of sunlight reaching the Earth's surface. By comparing the aerosol levels, solar radiation and crop yields, they concluded that the deflection of sunlight had a negative effect on the yields of many staple crops, including rice, wheat and maize.
If SRM involved deliberately sending sulphate,particles into the stratosphere, then the impacts on crop yield would probably be similar. The beneficial effects on crop yields from the resulting cooling would be "essentially negated" by the loss in crops due to the reduction in sunlight, failing to remove the threat climate change poses to agriculture and food security.
It seems that where SRM is concerned we still need much more research to understand the benefits and disadvantages of these types of options before we consider deploying them. In the meantime, we must accelerate efforts to mitigate all greenhouse gases across all sectors of the global economy.
[1] https://www.nature.com/articles/s41586-018-0417-3.epdf?referrer_access_token=BwOL4zq-i14KFPMfBHOuidRgN0jAjWel9jnR3
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