Climate change, high sea surface temperatures, acidity levels and carbon dioxide levels, coastal development, sewage discharge and overfishing are all contributing factors to coral reefs' demise. The study warns that the fate of the reefs all depends on how much these external causes can be curbed as well as the ability of coral reefs to adapt to changes. But, we have more to worry about than the coral reefs alone. Coral reefs, often called the rainforests of the sea, may only cover 0.2 percent of the earth's surface but they host about two million species that live in and around them. Another 200 million people rely on the reefs for food or as a means of income. So, if the coral reefs go, they won't be alone.