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How does solar radiation affect Earth’s global climate?

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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 radiation is the primary driver of Earth’s global climate, as the amount of energy received and its subsequent fate within the Earth system determine planetary temperatures.12

The Energy Budget

Earth’s climate is governed by the balance between incoming solar radiation and the energy returned to space. On average, about 46 percent of solar energy is absorbed by the surface, while the atmosphere absorbs approximately 23 percent. The remaining energy is reflected back to space by clouds, air molecules, and the surface (albedo). Because solar radiation is absorbed more intensely at low latitudes than at high latitudes, the atmosphere and oceans act as heat engines, circulating energy from the Equator toward the poles to compensate for this imbalance.1345

Climate Regulation

Once absorbed, solar energy is converted into heat and emitted by the surface as infrared radiation. Atmospheric gases—such as carbon dioxide and water vapour—trap this heat, a process known as the greenhouse effect, which keeps the planet significantly warmer than it would be otherwise. Geoengineering proposals often focus on manipulating these processes, such as increasing surface or atmospheric reflectivity to reduce solar heating, to address global warming.461