Something for us to be constantly aware of, wherever we are in the world, as this affects everyone. Coral reefs are about as colorful as the ocean gets—except when they bleach. Overly warm water can cause corals to spit out the colorful, photosynthetic, single-celled symbiotes that live inside them and produce most of their food. If the heat passes before the corals starve to death, their symbiotes can return, bringing color and health back to the coral.
As the globe warms, widespread bleaching events are occurring with
disturbing frequency. These tend to occur during times of El Niño
conditions in the Pacific, which add a temporary boost to the warming
water at some reefs. The current record-strength El Niño is sadly no
exception with up to 93% of the Great Barrier reef having been affected to one degree or another.
“We have now flown over 911 individual reefs in a helicopter and light
plane, to map out the extent and severity of bleaching along the full
2300km length of the Great Barrier Reef. Of all the reefs we surveyed,
only 7% (68 reefs) have escaped bleaching entirely. At the other end of
the spectrum, between 60 and 100% of corals are severely bleached on 316
reefs, nearly all in the northern half of the Reef.”