11. Global Warming and Coral Reefs
Drew Harvell
C. Drew Harvell, Ecology and Evolutionary Biology, and a global group of research colleagues predict that the Earth’s coral reefs—the world’s most biodiverse marine ecosystems—will not survive the global warming and acidification predicted for later this century if global action is not taken immediately. In a major international study, the researchers found that increasing carbon dioxide emissions from burning fossil fuels are making oceans warmer and more acidic and causing widespread coral disease and suppression of coral growth. The study showed that levels of CO2 could become unsustainable for coral reefs within five decades. Acidification threatens all marine animals and plants with calcareous skeletons, including corals, snails, clams, and crabs. Ecosystems that provide habitats for a large variety of marine species essential to oceans’ complex food chains are at stake. Coral reef ecosystems also provide livelihoods to 100 million people who live along the coasts of tropical developing countries. One example is diving tourism in the Caribbean, an industry that generates more than $100 billion a year. The loss of these ecosystems also exposes people to flooding, coastal erosion, and the loss of food and income from reef-based fisheries. For the short term, better management of overfishing and local stressors may increase reefs’ resilience to climate threats, but rising global CO2 emissions will rapidly outstrip the capacity of local coastal managers and policy makers to maintain the health of these critical ecosystems if the emissions continue unchecked. Determining how temperature stress decreases the immune response of corals, which are complicated animals, offers future promise for boosting the immunity of coral reefs.