How do changes in sea level affect coral reef growth?

Changes in sea level are a primary factor in the geological development and growth of coral reefs.

• Upward Growth: As sea levels rise—such as the postglacial rise over the last 10,000 years—reefs often grow upward to maintain a suitable depth for survival. This process allows them to mantle older, drowned landscapes. If a reef's foundation subsides, the coral must maintain sufficient growth to keep pace with the rising water to remain viable.123
• Emergence and Erosion: When sea levels fall or land is uplifted, reefs may be left above the high-tide mark. In these conditions, the reef is no longer growing and becomes subject to subaerial erosion and weathering.12
• Drowning: If the sea level rises too rapidly, a reef may be unable to keep pace with the changing depth. This can lead to the reef being "drowned," which may result in the loss of associated features like lagoons.3

Ultimately, the morphology of modern reefs is a result of both the biological tendency of corals to grow toward the surface and the historical fluctuations in sea level over millions of years.12