Warmer seas and a record hurricane season in 2005 have devastated more than half of the coral reefs in the Caribbean. In a report published by the World Conservation Union, 2005 was the hottest year on average since records began and had the most hurricanes ever recorded in a season. 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. The report concluded that a dramatic reduction in greenhouse gas emissions in the next 20 years would be extremely helpful in controlling further warming and dangerously high CO2 levels that will probably reduce the fitness of corals and limit the habitats for many other organisms living on Caribbean coral reefs.