The Day the Earth Nearly Died is a BBC Horizon documentary, focusing on the mystery of the Permian extinction, which scientists believe killed over 90% of all life on earth at the end of the Permian, some 250 million years ago. The program features palaeontologists and other scientists as they try to find clues to the great extinction. In the program, 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 cause 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 less than 1 million years.