Date: 2024-05-15 Page is: DBtxt003.php txt00012549
Natural Capital / Oceans / Coral Reefs
Coral Reefs in Dangerous Decline
GHOST REEFS ... Nearly all coral reefs will be ruined by climate change.
Burgess COMMENTARY
Peter Burgess
GHOST REEFS
Nearly all coral reefs will be ruined by climate change. According to a study in the journal Nature Scientific Reports, 99 percent of the world’s reefs will be affected by coral bleaching by the end of this century if climate change continues apace. When water is above ideal temperatures, coral expels the symbiotic algae that reside in its tissue and provide it with nutrients. This turns the reefs a ghostly white, and while the coral is not exactly dead at that point, it is more susceptible to disease — and death. A bleaching event on Australia’s Great Barrier Reef last year, for instance, left 67 percent of its shallow-water coral dead.
This isn’t just bad for the reefs themselves; it’s bad for the vast, biodiverse ecosystems that depend on them. That includes the humans who fish these reefs and who cater to reef-loving tourists. The National Marine Fisheries Service estimates that the commercial value of fisheries near coral reefs is over $100 million in the U.S. alone, and reef-related tourism generates billions of dollars a year.
Even if aggressive actions are taken to combat climate change, such as those pledged during the Paris climate talks, it could be too late to prevent mass bleaching events at many reefs, according to the study. Divers, you might want to book those trips sooner rather than later.
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Coral Bleaching
Abstract Increasingly frequent severe coral bleaching is among the greatest threats to coral reefs posed by climate change. Global climate models (GCMs) project great spatial variation in the timing of annual severe bleaching (ASB) conditions; a point at which reefs are certain to change and recovery will be limited. However, previous model-resolution projections (~1 × 1°) are too coarse to inform conservation planning. To meet the need for higher-resolution projections, we generated statistically downscaled projections (4-km resolution) for all coral reefs; these projections reveal high local-scale variation in ASB. Timing of ASB varies >10 years in 71 of the 87 countries and territories with >500 km2 of reef area. Emissions scenario RCP4.5 represents lower emissions mid-century than will eventuate if pledges made following the 2015 Paris Climate Change Conference (COP21) become reality. These pledges do little to provide reefs with more time to adapt and acclimate prior to severe bleaching conditions occurring annually. RCP4.5 adds 11 years to the global average ASB timing when compared to RCP8.5; however, >75% of reefs still experience ASB before 2070 under RCP4.5. Coral reef futures clearly vary greatly among and within countries, indicating the projections warrant consideration in most reef areas during conservation and management planning. 'http://truevaluemetrics.org/DBpdfs/Water/Oceans/Coral-1-srep39666.pdf' | Open PDF ... Coral-1-srep39666.pdf |