Have the coral reefs already crossed the tipping point?


Here’s the intro from this article by “Grist”:

About a year ago, the seas got unusually hot, even by our current, overheated standards. Twelve months of broken records later, the oceans are still more feverish than climate models and normal fluctuations in global weather patterns can explain.

When the seas turn into bathwater, it threatens the survival of the planet’s coral reefs, home to a quarter of all marine life and a source of sustenance for many people living along the world’s coasts. Mostly clustered in the shallow waters of the tropics, coral reefs have one of the lowest thresholds for rising temperatures of all the possible “tipping points,” the cascading feedback loops that set off large, abrupt changes in the ecosystems, weather patterns, and ice formations on Earth. Stable, existing systems wind up in new, completely different states: The lush Amazon rainforest, for example, might collapse into a grassy savanna. Coral reefs might transform into seaweed-smothered graveyards.

Earlier this month, the world officially entered its fourth — and probably worst — mass coral bleaching event in history, according to the National Oceanic and Atmospheric Administration and the International Coral Reef Initiative. Hot water causes corals to expel the tiny algae that live in their tissues, which provide them with food (through photosynthesis) and also a rainbow of pigments. Separated from their algae, corals “bleach,” turning ghostly white, and start to starve.