Environment and Ecology Coral Bleaching Event Context: Scientists have indicated that the fourth global coral bleaching event—the fastest and most widespread on record may have concluded by mid-2025. This event was confirmed by the National Oceanic and Atmospheric Administration (NOAA) on April 15, 2024. It caused heat stress leading to coral bleaching across 84% of the world's coral reef areas. It is believed to have ended following a coral bleaching event in Western Australia in early 2025. Coral Reefs Coral reefs are formed by tiny marine animals known as coral polyps. These animals extract calcium from seawater to build hard external skeletons, which gradually form rock-like structures. Although coral reefs cover less than 1% of the ocean floor, they support more than 25% of all marine life. About Coral Bleaching Coral bleaching occurs when corals turn white. This happens because they lose the microscopic algae (known as *zooxanthellae*) that live within them and provide both their color and food. Bleached corals do not always die, but they become weakened. They become susceptible to disease and lack sufficient nutrition; if this stress persists, they may die. Coral Bleaching Events The first global coral bleaching event occurred in 1998. The second took place in 2010. The third event, occurring between 2014 and 2017, was particularly severe due to intense heat stress and affected approximately 68% of coral reefs worldwide. Causes of Coral Bleaching Climate Change: Rising ocean temperatures are the primary cause. Even a slight temperature increase of around 1°C can lead to coral bleaching. Ocean Acidification: As oceans absorb excess carbon dioxide from the atmosphere, the water becomes more acidic. This weakens corals and hinders their ability to build their skeletons. Ultraviolet (UV) Radiation: Reduced cloud cover exposes corals to intense sunlight and high levels of UV radiation, causing stress. Human…
