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Why would solar-reflectance geoengineering not reduce carbon dioxide concentrations in the atmosphere?

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Illustration of various geoengineering techniques to address climate change, including carbon capture and storage methods like artificial trees, industrial scrubbers, and deep ocean CO2 storage, as well as solar reflectance strategies such as sulfur aerosols, reflective crops, cloud whitening, and orbital mirrors. The scene shows these interventions applied to land, sea, and atmosphere, with labeled features explaining each process. — Geoengineering Various geoengineering proposals designed to increase solar reflectance or capture and store carbon.

Solar-reflectance geoengineering does not reduce atmospheric carbon dioxide concentrations because it operates by manipulating the Earth's heat budget rather than by removing greenhouse gases from the atmosphere.1

These proposals aim to offset rising global temperatures by increasing the reflectance of incoming solar radiation, thereby reducing the amount of heat absorbed by the Earth's surface and lower atmosphere. While this approach may mitigate the heating effect of sunlight, it does not address the underlying cause of global warming—the accumulation of carbon dioxide (CO₂).1

Because solar-reflectance methods do not lower CO₂ levels, they fail to mitigate other critical consequences of elevated carbon dioxide, such as ocean acidification. In contrast, geoengineering approaches that focus on carbon sequestration are designed to remove CO₂ from the air, which can simultaneously address rising temperatures and the chemical changes occurring in the world's oceans.1