Parts of these reefs are now dying. At least one species of coral may have already become extinct due to bleaching. Climate changes caused by global warming could put reefs under stress. Biological diversity may decrease as plants and animals tolerant of warmer water invade the reef. Some species may be killed directly by the higher temperatures.
Coral reefs act as natural breakwaters.
If rising sea level or higher water temperature cause the reef to die or to grow more slowly, the nearby coastline could erode. This shoreline on Bali is already eroded because the reef offshore was destroyed in this case by human activities. As more areas of the ocean become warmer, reefs might actually expand their geographical range. Warmer oceans might cause reefs to expand their geographical range, if their growth is not blocked by other impacts of climate change. Climate changes caused by global warming could put the reef under stress.