Half of global coral cover destroyed since the 1950s

The world’s coral reef cover has halved since the 1950s, ravaged by global heating, overfishing, pollution and habitat destruction, a trend that is projected to continue as the planet continues to heat in the 21st century.

Diversity of species on reefs has dropped by more than 60% and total reef cover had approximately halved.

“Marine heatwaves are rapidly intensifying, leading to more frequent and severe bleaching events, including on some of the world’s most isolated and pristine coral reefs”.

“Over the last few years, Caribbean reefs have been clobbered by hurricanes and new diseases, both linked to ocean warming. Frankly, the global picture for coral reefs is pretty grim”.

The world’s oceans absorbed more than 90% of the heat trapped by greenhouse gases and average water temperatures have continued to rise as the planet heats.

The lobbying push that killed off a fight to save the Great Barrier Reef

The Great Barrier Reef, the size of Italy or Japan, is where global heating is a present-day catastrophe. It has suffered three mass coral bleaching events since 2015, killing up to 50% of its shallow water coral, with no reprieve in sight.

That conclusion prompted a push to have Unesco add the reef to its “in danger” list. But after a global campaign, ranging from a snorkelling jaunt for ambassadors to an eight-day lobbying trip taking in Hungary, Oman and the Maldives, the 21-country World Heritage Committee ignored Unesco’s scientific assessment.

World’s coral scientists warn action is needed now to save even a few reefs from climate change

We saw damage almost everywhere, from the Bahamas to the Great Barrier Reef.

Corals can become stressed when temperatures around them rise just 1˚C (1.8˚F) above their tolerance level. With water temperature elevated from global warming, even a minor heat wave can become devastating.

If global temperatures rise by 2˚C (3.6˚F) or more, only about 1% will still exist.

Great Barrier Reef: leading scientists praise Unesco’s ‘in danger’ warning

Five of the world’s leading reef and climate scientists have thanked Unesco for recommending the Great Barrier Reef be listed as world heritage “in danger”, saying it was the right decision in part because Australia had not “pulled its weight” in reducing emissions.

Time running out to save coral reefs

“While 63% of reefs are projected to continue to accrete by 2100 under the low-impact pathway, 94% will be eroding by 2050 under the worse-case scenario,” Dr Cornwall said. “And no reef will continue to accrete at rates matching projected sea-level rise under the medium and high-impact scenarios by 2100.”

The Great Barrier Reef has lost over half its corals

“We found the number of small, medium and large corals on the Great Barrier Reef has declined by more than 50% since the 1990s,” said co-author Professor Terry Hughes, from CoralCoE.