HUMAN ACTIVITIES ARE threatening the health of the world's oceans. More than 80 percent of marine pollution comes from land-based activities. From coral bleaching to sea level rise, entire marine ecosystems are rapidly changing.
Global warming is causing sea levels to rise, threatening coastal population centers. Many pesticides and nutrients used in agriculture end up in the coastal waters, resulting in oxygen depletion that kills marine plants and shellfish. Factories and industrial plants discharge sewage and other runoff into the oceans. Oil spills pollute the oceans, though U.S. water-sewage treatment plants discharge twice as much oil each year as tanker spills. Air pollution is responsible for almost one-third of the toxic contaminants and nutrients that enter coastal areas and oceans. The United Nations Food and Agriculture Organization estimates that 31.4 percent of fish stocks are either fished to capacity or over-fished.
