Earlier this month, the Global Coral Reef Monitoring Network released the first report collating global statistics on corals, documenting the status of reefs across 12,000 sites in 73 countries over 40 years. Overall, they report, the world has lost 14 percent of its corals from 2009 to 2018 — that’s about 4,517 square miles of coral wiped out.

"If this had happened to the Amazon, if overnight it had turned white or black, it would be in the news everywhere," said Voolstra. "Because it’s underwater, no one notices."

Corals are facing tough times from global warming: Prolonged marine heat waves, which are on the rise, cause corals to expel their symbiotic algae (zooxanthellae), leaving the bleached corals weak and vulnerable. Local pollution continues to be a problem for corals, but global warming is emerging as the predominant threat. In 2018, the International Panel on Climate Change reported that 1.5 degrees Celsius of global warming would cause global coral reefs to decline by 70-90 percent (warming stands at 1.2 degrees C). A 2-degree C warmer world would lose more than 99 percent of its corals.

There are some hints of hope. The Global Coral Reef Monitoring Network report shows that corals can recover globally if given about a decade of reprieve from hot waters. Some spots — particularly the Coral Triangle in East Asia, which hosts nearly a third of global corals — have bucked the trend and seen coral growth. There are hints that corals might be adapting to warmer conditions. And research is burgeoning on creative ways to improve coral restoration, from selectively breeding super corals to spreading probiotics on stressed reefs.

Read the full article about coral reefs by Nicola Jones at GreenBiz.