The window for saving the world’s coral reefs is rapidly closing
The world’s reefs are under siege from global warming, according to a novel study published today in the prestigious journal Science.
For the first time, an international team of researchers has measured the escalating rate of coral bleaching at locations throughout the tropics over the past four decades. The study documents a dramatic shortening of the gap between pairs of bleaching events, threatening the future existence of these iconic ecosystems and the livelihoods of many millions of people.
“Before the 1980s, mass bleaching of corals was unheard of, even during strong El Niño conditions, but now repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world as temperatures continue to rise.”
The study establishes a transition from a period before the 1980s when bleaching only occurred locally, to an intermediate stage in the 1980s and 1990s when mass bleaching was first recorded during warmer than average El Niño conditions, and finally to the current era when climate-driven bleaching is now occurring throughout ENSO (El Niño-Southern Oscillation) cycles.
The researchers show that tropical sea temperatures are warmer today during cooler than average La Niña conditions than they were 40 years ago during El Niño periods.
“Coral bleaching is a stress response caused by exposure of coral reefs to elevated ocean temperatures. When bleaching is severe and prolonged, many of the corals die. It takes at least a decade to replace even the fastest-growing species,” explained co-author Prof Andrew Baird of Coral CoE.
“For example, the Great Barrier Reef has now bleached four times since 1998, including for the first time during back-to-back events in 2016 and 2017, causing unprecedented damage,” explained Prof Hughes. “Yet the Australian government continues to support fossil fuels.”
“We hope our stark results will help spur on the stronger action needed to reduce greenhouse gases in Australia, the United States and elsewhere,” says Prof Hughes.
The paper “Spatial and temporal patterns of mass bleaching of corals in the Anthropocene” is now available here.
Associate Professor Julia Baum University of Victoria, Department of Biology
Victoria, BC CANADA
Phone: 1-250-858-9349 (PST/UTC -8)
Associate Professor Michael Berumen King Abdullah University of Science and Technology, Red Sea Research Center
Thuwal, SAUDI ARABIA
Phone: +966 544 700 019 (available from 3-4 Jan, MSK/UTC + 3; 5-7 Jan, CET/UTC + 1)
C. Mark Eakin, Ph. D. National Oceanic & Atmospheric Administration
Silver Spring, MD U.S.A.
Phone: 1-301-502-8608 (EST/UTC -5)
Prof Nicholas Graham Lancaster University, Lancaster Environment Centre
Lancaster, UNITED KINGDOM
Tel: +44 (0) 7479 438 914 (available from 4 Jan, GMT/UTC)
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Townsville, QLD AUSTRALIA
Phone: +61 (0)7 4781 6067, +61 (0) 428 785 895 (AEST/UTC +10)
Aerial survey images from Cape York to Mossman on 25/03/2016, Great Barrier Reef. Credit: ARC CoE for Coral Reef Studies/ Terry Hughes