Final answer:
When atmospheric carbon dioxide dissolves in seawater, it forms bicarbonate and carbonate ions, contributing to the production of calcium carbonate for marine organisms' shells. Rising CO2 levels cause ocean acidification, which negatively affects the ability of marine life to create their exoskeletons, posing a threat to the ocean ecosystem.
Step-by-step explanation:
When carbon dioxide from the atmosphere dissolves in seawater, it reacts with water to form bicarbonate and carbonate ions. A large proportion of carbon in the ocean exists as bicarbonate ions. These ions can react with calcium in seawater to form calcium carbonate (CaCO3), which is critical for the shells of marine organisms. As these organisms die, their shells become sediments, contributing to the geologic formation of limestone, the largest carbon reservoir on Earth. However, as atmospheric CO2 levels rise, the ocean absorbs more, leading to ocean acidification. This decrease in pH can make it harder for marine life like corals and shellfish to produce their calcium carbonate exoskeletons, threatening their survival and the overall marine ecosystem.
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