The bleaching of the Great Barrier Reef is one of the most obvious signs of global warming. Scientists, however, warn that it isn't the only marine habitat at risk. About 70 percent of the world's reefs have been affected by global warming and the majority of reefs within the United States could die off within a few decades.

The Great Barrier Reef has gotten most of the media's attention, but the U.S. reefs aren't faring much better. America's reefs, which are concentrated in Hawaii, Florida, Guam and Puerto Rico, are under severe threat.

"The idea we will sustain reefs in the US 100 years from now is pure imagination," said oceanographer Kim Cobb. "At the current rate it will be just 20 or 30 years, it's just a question of time. The overall health of reefs will be severely compromised by the mid-point of the century and we are already seeing the first steps in that process."


Coral reefs, which serve as a habitat for many types of marine life, get their vibrant colors from a type of algae known as zooxanthellae. These brightly colored algae provide the reef with food and oxygen, but exposure to carbon dioxide led the ocean's waters to increase in temperature to the point where the algae can't survive. As the algae die off, the reefs also die.

As troubling as the loss of the reefs are, the damage could herald the loss of many of the marine species that call them off. The reefs support millions of different forms of marine life and their decline has already had an impact. There are 22 species classified as "threatened" with three more being listed as "endangered." As of now, it's too soon to determine the extent of the damage that would follow the loss of the reefs, but it is almost guaranteed that we would lose many examples of marine life.

The Cause Is Clear

The cause of this bleaching has been linked to global warming and the troubling fact is that — without addressing the underlying issue — there is little that can be done to preserve the reefs. Many of Hawaii's reefs exist within protected zones, but they can't be protected from rising water temperatures which have become increasingly problematic in recent years. Scientists who study the reefs warn that the reefs will continue to decline unless the issue of climate change is addressed. The reefs were hit the hardest in 2015, but things have not gotten much better. Unless the trend in rising ocean temperatures is reversed, the reefs will continue to decline.

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