Ocean acidification is sometimes called “climate change’s equally evil twin,” and for good reason: it’s a significant and harmful consequence of excess carbon dioxide in the atmosphere that we don’t see or feel because its effects are happening underwater. At least one-quarter of the carbon dioxide (CO2) released by burning coal, oil and gas doesn’t stay in the air, but instead dissolves into the ocean.
Acidification and Ocean warming from increasing levels of atmospheric CO2 represent major global threats to coral reefs, and are in many regions exacerbated by local-scale disturbances such as over fishing and nutrient enrichment. Our understanding of global threats and local-scale disturbances on reefs is growing.
In 2008, a worldwide study estimated that 19% of the existing area of coral reefs has already been lost, and that a further 17% is likely to be lost over the subsequent 10–20 years.Only 46% of the world’s reefs could be currently regarded as in good health Coral reefs are found in a wide range of environments, where they provide food and habitat to a large range of organisms as well as providing many other ecological goods and services.
Harmful algal blooms can cause numerous problems in the environment. The US EPA describes algae blooms as over growths of algae in the water, which can be caused when nutrient pollution (nitrogen and phosphorus) in the water fuels algal growth. Harmful algal blooms can be harmful to aquatic life, as some produce toxins that can make animals sick, while others can die off in large quantities and deplete oxygen in the water when they decompose.