Warmer seas and a record hurricane season in 2005 have devastated more than half of the coral reefs in the Caribbean, according to scientists. In a report published on Wednesday, the World Conservation Union (IUCN) warned that this severe damage to reefs would probably become a regular event given current predictions of rising global temperatures as a result of climate change.
According to the report, 2005 was the hottest year on average since records began and had the most hurricanes ever recorded in a season. Large hotspots in the Atlantic and the Gulf of Mexico powered strong tropical hurricanes such as Katrina, which developed into the most devastating storm ever to hit the US.
In addition to the human cost, the storms damaged coral by increasing the physical strength of waves and covering the coast in muddy run-off water from the land. The higher sea temperature also caused bleaching, in which the coral lose the symbiotic algae they need to survive. The reefs then lose their color and become more susceptible to death from starvation or disease.
Carl Gustaf Lundin, head of the IUCN's global marine program, said: "Sadly for coral reefs, it's highly likely extreme warming will happen again. When it does, the impacts will be even more severe. If we don't do something about climate change, the reefs won't be with us for much longer."
Some of the worst-hit regions of the Caribbean, which contains more than 10 percent of the world's coral reefs, included the area from Florida through to the French West Indies and the Cayman Islands.
In August 2005 severe bleaching affected between 50 percent and 95 percent of coral colonies and killed more than half, mostly in the Lesser Antilles.
The IUCN report highlights pressures on coral reefs in addition to those of overfishing and pollution identified in recent years. A recent study found that reefs near large human populations suffered the most damage.
Coral reefs are an important part of the marine ecosystem, supporting an estimated 25 percent of all marine life including more than 4,000 species of fish. They provide spawning, nursery, refuge and feeding areas for a wide variety of other creatures such as lobsters, crabs, starfish and sea turtles. Reefs also play a crucial role as natural breakwaters, protecting coastlines from storms.
"It's quite clear that the structure and their function as they are right now in the Caribbean is quite severely impeded," Lundin said. "Over the next few decades we will see a large reduction in the number of reef areas."
Reefs also boost the local economy -- in the Caribbean coral reefs provide more than US$4 billion a year from fisheries, scuba-diving tourism and shoreline protection. According to an analysis by the World Resources Institute, coral loss in the region could cost the local economy up to US$420 million every year.
"The only possible way to sustain some live coral on the reefs around the world will be to carefully manage the direct pressures like pollution, fishing and damaging coastal developments, and hope that some coral species are able to adapt to the warmer environment," the report said.
Lundin said managing these more direct pressures on reefs would lessen the impact of rising sea temperatures.
"Over time we'll also see transitional species; if we give nature enough time it's possible some coral will actually cope with the warmer water and we'll get another composition of the reef," he said.