A variety of human activities have led to the recent global decline of reef-building corals. The ecological, social, and economic value of coral reefs has made them an international conservation priority. Coral reefs around the world are being destroyed at a faster rate than they can recover, therefore putting them in great danger. One of the largest causes of the destruction of the reefs is global warming, which has been increasing the temperature of the ocean water resulting in coral bleaching. Human-induced climate change has already led to substantial changes in a variety of ecosystems. Coral reefs are particularly vulnerable to rises in ocean temperature as a result of climate change because they already live near their thermal limits. .
A coral reef is a ridge formed in shallow ocean water by accumulated calcium-containing exoskeletons of coral animals, certain red algae, and mollusks. Coral reefs are tropical, forming only where surface waters are never cooler than sixty-eight degrees Fahrenheit. Climate change increases ocean temperatures, reducing the level of calcium in the sea. This calcium is essential to corals and other reef organisms to build their skeletons. One-third of the extra carbon dioxide in the atmosphere is absorbed through the ocean surface. This acidifies shallow waters, making it harder for reef organisms to get the minerals they need. .
Anyone who's ever scuba dived at a coral reef and seen the perfect handprint of dead coral can appreciate how fragile and delicate this ecosystem is. When people think of coral, they think of the sharp rocks they step on when they're on vacation. When in reality, what they are stepping on is hundreds of living organisms. Each little polyp or head is an individual living animal. Stepping on the coral at the beach isn't the only thing that is killing them. People all around the world are killing corals simply by driving to work every day.