New research from Indonesia indicates that from about 6,000 to 10,000 years ago, when the ocean was warmer than today, coral reef growth was rapid, averaging ~6 mm per year. [emphasis, links added]
Sea levels rose rapidly from the Early to Mid-Holocene in this region, as they were up to two meters higher than today 6,000 years ago. The higher sea levels meant there was more room for coral reef growth.
As the ocean cooled and sea levels fell ~2 meters from the Mid-Holocene highstand, coral growth slowed to ~2-3 mm per year.
Today, corals are only growing at rates of ~1 mm per year, as the water depths are too low to accommodate reef expansion.
In fact, coral coverage “has declined on the flats over the last few decades,” as the “accommodation space is less than a meter at points.”
Research from the Great Barrier Reef region (e.g., Leonard et al., 2020) also indicates coral growth experienced “turn-off” periods during cold centuries (such as the Little Ice Age) with falling sea levels.
When the ocean was “~1-2°C warmer than present” and sea levels were “~1.0 meter higher than present,” this “allowed reefs to accrete uninhibited.”
Read more at No Tricks Zone
