The apocalypse. The end-Permian mass extinction of 251 million years ago was associated with six degrees of warming, and wiped out 90% of life on Earth.
Huge firestorms sweep the planet as methane hydrate fireballs ignite.
Seas turn anoxic and release poisonous hydrogen sulphide.
Humanity’s very survival as a species in question.
Notes from Mark Lynas author of Six Degrees: Our Future on a Hotter Planet
Six Degrees video description from National Geographic