4/5℃, not enough to kill the world, but then Wignall realized this was only part of the story.
For the methane to melt, something must already have raised world temperatures 4/5℃.
The methane would then have raised them a further 5℃ more, to a total of 10℃.
This would have been more than enough to kill practically every living thing.
Wignall slowly realized what the evidence from Greenland was telling him.
There had not been one Permian killer, but two.
Paul Wignall now put together the extraordinary story of what might have happened 250 million years ago.
It started, as many had thought, with the Siberian Traps.
Thousands of miles of lava flows would have burst from cracks deep in the earth's crust.
This was the first killer.