Video
What is SRM?
Sunlight reflection methods – also known as solar geoengineering or solar radiation modification (SRM) – are a set of ideas to slow or stop global warming by reflecting a small fraction of sunlight away from the earth.
Transcript
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Earth is heated by the sun and it is kept warm by a natural greenhouse effect.
Our emissions of CO2 and other greenhouse gases are strengthening this heat-trapping effect, causing the Earth to warm, and the climate to change(1).
While efforts are underway to cut emissions, progress is slow(2), and the risks of climate change are growing(3).
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Sunlight Reflection Methods – also known as solar radiation modification – or S-R-M – are a set of proposals to slow or stop global warming by reflecting a small fraction of sunlight away from the earth.
The leading SRM proposals both involve releasing tiny particles into the atmosphere:
- Stratospheric aerosol injection would directly reflect light.
- Marine cloud brightening would change clouds to make them more reflective(4).
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While SRM could cool the planet, there are some unanswered questions:
- Could SRM cause some regions to see greater climate risks?
- Could SRM undermine efforts to cut emissions?
- Who would decide where and how SRM are used?
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Whether SRM should be developed as a way to manage climate risks is unclear.
What is clear, however, is that information should be accessible to everyone so that informed decisions can be made about these ideas.
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Endnotes
- IPCC Summary for Policymakers. In: Masson-Delmotte V, Zhai P, Pirani A, et al. (eds) limate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press, 2021, pp. 3–32.
- UNEP. Emissions Gap Report 2023: Broken Record – Temperatures hit new highs, yet world fails to cut emissions (again). United Nations Environment Programme. Epub ahead of print November 2023. DOI: 10.59117/20.500.11822/43922.
- IPCC. Impacts of 1.5°C Global Warming on Natural and Human Systems. In: Global Warming of 1.5°C. Cambridge University Press, 2022, pp. 175–312.
- Latham J, Bower K, Choularton T, et al. Marine cloud brightening. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 2012; 370: 4217–4262.
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