Coral bleaching and global climate change: Scientitic findings and policy recommendations

In 1998, tropical sea surface temperatures were the highest on record, topp ing off a 50-year trend for some tropical oceans. In the same year, coral r eefs around the world suffered the most extensive and severe bleaching (los s of symbiotic algae) and subsequent mortality on record. These events may not be attributable to local stressors or natural variability alone but wer e likely induced by nit underlying global phenomenon. It is probable that a nthropogenic global warming has contributed to the extensive coral blenchin g that has occurred simultaneously throughout the reef regions of the world The geographic extent, increasing frequency, and regional severity of mass bleaching events are an apparent result of a steadily rising baseline of m arine temperatures, combined with regionally specific El Nino and La Nina e vents. The repercussions of the 1998 mass bleaching and mortality events wi ll be far-reaching. Human populations dependent on reef services face losse s of marine biodiversity, fisheries, and shoreline protection. Coral bleach ing events may become more frequent and severe as the climate continues to warm, exposing coral reefs to an increasingly hostile environment. This glo bal threat to corals compounds the Effects of more localized anthropogenic factors that already place reefs at risk. Significant attention needs to be given to the monitoring of coral reef ecosystems, research on the projecte d and realized effects of global climate change, and measures to curtail gr eenhouse gas emissions. Even those reefs with well-enforced legal protectio n as marine sanctuaries, or those managed for sustainable use, are threaten ed by global climate change.