Ocean Ocean An ocean () is a body of saline water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans. The word "ocean" is often used interchangeably with "sea" in American English. Strictly speaking, a "sea" is a body of saline water (generally a division of the world ocean) partly or fully enclosed by land, though "the sea" refers also to the oceans. Saline water covers approximately and is customarily divided into
The Day The Earth Nearly Died it is argued that the Permian extinction came in 3 stages; the first was caused by volcanic activity in the great Siberian Traps. This is proposed to have caused global warming, which in turn killed much of the life on land. Second, it warmed up the sea, which killed much of the marine life. As the sea became warmer, the ocean floor released a massive amount of methane. As the methane reached the atmosphere, the earth became even warmer, which led to the extinction of even more lifeforms on land. In the program, the extinction is argued to have lasted