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How could warmer ocean water reduce the ocean’s ability to absorb carbon dioxide?

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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.

Warmer ocean water reduces the ocean’s ability to absorb carbon dioxide primarily because the solubility of gases in liquids decreases as temperature rises; consequently, warmer surface waters hold less dissolved CO₂.12

This reduction in absorption capacity acts as a positive feedback mechanism for global warming. As the ocean becomes less efficient at sequestering atmospheric carbon, the pace of CO₂ buildup in the atmosphere accelerates.12

Additionally, ocean warming can disrupt the thermohaline circulation—a global pattern of oceanic flow that helps transport carbon from the surface to the deep ocean. By reducing the temperature gradient between cold and warm regions, warming inhibits the sinking of surface waters, which further reduces the efficiency of the "solubility pump" that buries carbon in the deep sea. Furthermore, rising temperatures and increased acidity can harm marine organisms that contribute to the "biological pump," which also plays a critical role in maintaining the ocean as a carbon sink.12