Coral reefs are the most sensitive of all ecosystems to global warming, pollution, and new diseases. They will be first to go as a result of climate change. As the most important resources for fisheries, tourism, shore protection, and marine biodiversity for more than a hundred countries, this will be a huge disaster. Almost all reefs have already been heated above their maximum temperature thresholds. Many have already lost most of their corals, and temperature rise in most places gives only a few years before most corals die from heatstroke.