I am quite dubious of this claim. Our current coral reefs didn't exist during the Younger-Dryas. They were dry land. Bleached coral isn't dead. It has just

I am quite dubious of this claim. Our current coral reefs didn't exist during the Younger-Dryas. They were dry land. Bleached coral isn't dead. It has just expelled it's algae due to stress. Coral are also broadcast spawners. Polyps ride ocean currents until they find a place to build their home, the actual reef structure. Coral reefs may move around but they aren't going to just go extinct.