Scientists warn US coral reefs are on course to disappear within decades

Keisha Bahr

Keisha Bahr

The Guardian

May 30, 2017

Oliver Milman

New Noaa research shows that strict conservation measures in Hawaii have not spared corals from a warming ocean in one of its most prized bays.

Some of America’s most protected corals have been blighted by bleaching, with scientists warning that US reefs are on course to largely disappear within just a few decades because of global warming.

New research has shown that strict conservation measures in Hawaii have not spared corals from a warming ocean in one of its most prized bays, with the National Oceanic and Atmospheric Administration predicting yet more bleaching is likely off Hawaii and Florida this summer.

“I’m concerned because we could very well see bleaching return to Florida, parts of the Caribbean and Hawaii,” said Mark Eakin, a coral reef specialist at Noaa.

“It won’t be as severe as 2015, but we’ve now moved into a general pattern where warmer than normal temperatures are the new normal. US reefs have taken a severe beating. We are looking at the loss or at least severe degradation of most reefs in the the coming decades.”

A global coral bleaching event has shifted between the northern and southern hemispheres since 2014, affecting around 70% of the world’s reefs. The “terminal” condition of Australia’s sprawling Great Barrier Reef, which suffered bleaching along two-thirds of its 1,400-mile length in 2016 and 2017, has provoked the greatest alarm.

But scientists have pointed out that America’s main reefs, found off Hawaii, Florida, Guam and Puerto Rico, are facing a largely unheralded disaster.

“The idea we will sustain reefs in the US 100 years from now is pure imagination. At the current rate it will be just 20 or 30 years, it’s just a question of time,” said Kim Cobb, an oceanographer at Georgia Tech. “The overall health of reefs will be severely compromised by the mid-point of the century and we are already seeing the first steps in that process.”

Bleaching occurs when prolonged high temperatures in the ocean cause coral to expel the symbiotic algae that provides it with food and colour. The coral turns a ghostly white, and can die if tolerable conditions don’t return. The world’s oceans have absorbed more than 90% of the extra heat generated by the release of greenhouse gases from human activity.

Cobb said regular annual bleaching events, which recent research has forecast happening by the 2040s, will “undercut the resilience of these ecosystems”. Corals not killed off by bleaching are left weakened by the process and are less likely to survive if repeatedly subjected to above-average temperatures.

“As scientists we are breathlessly trying to catch up,” said Cobb. “Things started to run away from us around 10 years ago but we were perhaps a little naive in not realizing that.”

Read more at The Guardian.