The world's coral reefs are close to 25 percent larger than we thought.
"The world's coral reefs are close to 25 percent larger than we thought. By using satellite images, machine learning and on-ground knowledge from a global network of people living and working on coral reefs, we found an extra 64,000 square kilometers (24,700 square miles) of coral reefs – an area the size of Ireland.
That brings the total size of the planet's shallow reefs (meaning 0-20 meters deep) to 348,000 square kilometers – the size of Germany. This figure represents whole coral reef ecosystems, ranging from sandy-bottomed lagoons with a little coral, to coral rubble flats, to living walls of coral.
Within this 348,000 km² of coral is 80,000 km² where there's a hard bottom – rocks rather than sand. These areas are likely to be home to significant amounts of coral – the places snorkelers and scuba divers most like to visit.
You might wonder why we're finding this out now. Didn't we already know where the world's reefs are?
Previously, we've had to pull data from many different sources, which made it harder to pin down the extent of coral reefs with certainty. But now we have high resolution satellite data covering the entire world – and are able to see reefs as deep as 30 meters down.
Pictured: Geomorphic mapping (left) compared to new reef extent (red shading, right image) in the northern Great Barrier Reef.
[AKA: All the stuff in red on that map is coral reef we did not realize existed!! Coral reefs cover so much more territory than we thought! And that's just one example. (From northern Queensland)]
We coupled this with direct observations and records of coral reefs from over 400 individuals and organizations in countries with coral reefs from all regions, such as the Maldives, Cuba, and Australia.
To produce the maps, we used machine learning techniques to chew through 100 trillion pixels from the Sentinel-2 and Planet Dove CubeSat satellites to make accurate predictions about where coral is – and is not. The team worked with almost 500 researchers and collaborators to make the maps.
The result: the world's first comprehensive map of coral reefs extent, and their composition, produced through the Allen Coral Atlas. [You can see the interactive maps yourself at the link!]
The maps are already proving their worth. Reef management agencies around the world are using them to plan and assess conservation work and threats to reefs."
-via ScienceDirect, February 15, 2024
