Episodic Reef Growth in the Northern South China Sea linked to Warm Climate During the Past 7,000 Years: Potential for Future Coral Refugia

Abstract

AbstractHigh‐precision uranium‐thorium (U‐Th) dating of dead branching corals from Luhuitou reef, Sanya, northern South China Sea indicates that the reef framework grew episodically over the past 7,000 years. Episodes of coral reef growth (“switch‐on” phases) occurred in response to regional warming during the mid‐Holocene Climate Optimum, Medieval Warm Period, and Current Warm Period, when the East Asian summer monsoon was strong and the East Asian winter monsoon was weak. In contrast, episodes when reef growth dramatically slowed or ceased (“switch‐off” phases) occurred during comparatively cold periods (e.g., Dark Age Cold Period and Little Ice Age) and are linked to abrupt weakening of the East Asian summer monsoon and concurrent strengthening of the East Asian winter monsoon. In the context of global warming, the northern South China Sea may become an important refugium for coral reef growth of up to 2 °C above present, but only if local anthropogenic pressures are reduced.