How Does the Ocean Absorb and Release Carbon Dioxide?

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This forms carbonic acid, which can dissociate and increase hydrogen ion concentration, lowering pH. Increased uptake of anthropogenic carbon dioxide therefore causes ocean acidification, harming corals and other organisms that build calcium carbonate structures.

Phytoplankton remove dissolved carbon dioxide through photosynthesis. Carbon enters marine food webs, and some dead organic matter sinks, transferring carbon toward deep-water or seabed stores.

Cold North Atlantic waters are an important uptake region. However, warming surface water may weaken absorption, leaving more carbon dioxide in the atmosphere and creating a positive feedback.

A common misconception is that ocean uptake removes carbon permanently. In reality, air-sea exchange is dynamic, and stored carbon may later be released.

Exam Technique

For an explain question, use linked cause-and-effect statements involving concentration gradients, dissolution, temperature, and outgassing. In a systems diagram, draw the atmosphere and ocean as storages and absorption and release as arrowed flows. Connect acidification to impacts such as coral loss and reduced fishery livelihoods.