What factor threatens coral reefs through increased levels of carbon dioxide?

• A. Ocean warming
• B. Overfishing
• C. Pollution from plastics
• D. Ocean acidification

Answer: (D)

Increased levels of carbon dioxide in the atmosphere lead to higher concentrations of CO2 being absorbed by the oceans, which causes ocean acidification. This process results in the reduction of carbonate ions, which are essential for corals and other marine life that rely on calcium carbonate to build their skeletons and shells. As the water becomes more acidic, it becomes more difficult for corals to sustain their structures, leading to weakened reefs. This process also affects the entire ecosystem that depends on coral reefs, as many marine species rely on these reefs for habitat and protection. Therefore, ocean acidification directly threatens the health and resilience of coral reefs, making it the correct choice in the context of how increased carbon dioxide levels can impact these vital marine ecosystems.