(Family Features) The ocean covers more than 70% of Earth's surface, produces more than half of the world's oxygen and is home to more than 700,000 species. However, according to the Intergovernmental Panel on Climate Change, scientists estimate if nothing is done, 90% of the world's tropical reefs will be gone by 2043, threatening 25% of marine life and impacting nearly 500 million people who depend on them for food, income and coastal protection.