Oceans cover about 71% of the earth's surface and contain 97% of its water. They are a key factor in making the earth habitable for humankind. The sea ultimately provides our drinking water, weather, climate, much of our food, and even half of the oxygen we breathe. In addition, oceans are one of the main sources of the world's biodiversity, underscoring their ecological significance.
They constitute over 90 per cent of the planet's habitable space and contain about 250,000 known species, with many more yet to be discovered. At least two-thirds of the world's marine species are still unidentified.
Consequently, factors that negatively affect marine biodiversity also threaten the planet's ability to support life as we know it and to function normally. Climate change, overfishing, and plastic in the ocean are threatening to trigger dramatic changes in this ecosystem that could have severe effects on human life in the medium term. The term by-catch describes the accidental capture of non-target species, including seabirds, dolphins, sharks and marine turtles. 40% of fish caught worldwide are by-catch according to WWF, partly thrown back into the sea, either dead or dying.
Plastic in the ocean is harming corals and biodiversity. By 2050, there will be more plastic than fish there. Read more here:
https://education.nationalgeographic.org/resource/all-about-the-ocean/