Solar geoengineering, also known as solar radiation modification (SRM), is a type of climate engineering that aims to reflect sunlight back to outer space to limit or offset human-caused climate change. It is a set of speculative technologies that artificially intervene in the climate systems of our planet. The two main approaches being researched are stratospheric aerosol injection (SAI) and marine cloud brightening (MCB) . Other methods have been proposed, including a variety of space-based approaches, but they are generally considered less viable.

Solar geoengineering is not a substitute for reducing greenhouse gas emissions but would act as a temporary measure to limit warming while emissions of greenhouse gases are reduced and carbon dioxide is removed. If solar geoengineering were to cease while greenhouse gas levels remained high, it would lead to "large and extremely rapid" warming.

While solar geoengineering could have a rapid cooling effect on atmospheric temperature, if the intervention were to suddenly stop for any reason, the cooling would soon stop as well. It is estimated that the cooling impact from SAI would cease 1–3 years after the last aerosol injection, while the impact from marine cloud brightening would disappear in just 10 days.

Solar geoengineering is highly controversial, risky, and uncertain. It does not address the root cause of climate change, which is greenhouse gas emissions and concentrations. Instead, it focuses on symptom treatment, seeking to limit global warming by merely masking the effect of greenhouse gas emissions. The Union of Concerned Scientists opposes the deployment of solar geoengineering because it poses unacceptably high environmental, social, and geopolitical risks.

In conclusion, solar geoengineering is a type of climate engineering that aims to reflect sunlight back to outer space to limit or offset human-caused climate change. It is a set of speculative technologies that artificially intervene in the climate systems of our planet. While it could have a rapid cooling effect on atmospheric temperature, it is highly controversial, risky, and uncertain. It is not a substitute for reducing greenhouse gas emissions but would act as a temporary measure to limit warming while emissions of greenhouse gases are reduced and carbon dioxide is removed.