How do coral reefs relate to changes in sea level?

Reef-building corals need warm, clear, sunlit water, so they typically thrive in shallow tropical seas. As corals and other organisms secrete calcium carbonate, they build large reef frameworks over time. Because reefs grow upward toward light, they can keep pace with slowly rising sea level if conditions are favorable. If sea level rises too quickly, or if water becomes too warm, acidic, or cloudy, reef growth may not keep up. Reef terraces and fossil reefs provide important records of past sea-level changes.