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How does Earth’s albedo affect the amount of sunlight absorbed by the planet?

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World map shaded to show annual carbon dioxide emissions by country in 2022, with China, the United States, and India highlighted as top emitters in dark red. A bar chart below lists the top ten emitting countries by million metric tons. — Greenhouse gas Map of annual carbon dioxide emissions by country in 2014.

Earth’s albedo is the measure of the planet’s reflective capacity, representing the fraction of incoming solar radiation that is reflected back into space by clouds, the atmosphere, and reflective surface features like ice and snow.12

This reflective property directly dictates how much solar energy is absorbed by the planet. For every 100 units of incoming solar radiation, approximately 30 units are reflected back to space due to Earth's planetary albedo. The remaining 70 units are absorbed by the atmosphere, clouds, or the surface, where they are converted into heat energy.23

Because albedo determines the proportion of sunlight that is reflected rather than absorbed, it plays a critical role in global warming. For example, the loss of sea-ice in the Arctic reduces the region's albedo, causing it to absorb more solar energy. This creates a positive feedback loop where increased heat absorption leads to further ice melt, which in turn lowers the albedo and increases absorption even more.1