 That point is well illustrated. You can again see the spikes of mass extinctions measured by the increase in global temperatures, with the largest spike representing the Permian mass extinction. Wignall told me, there have been a lot of disasters and crises in the geological past. It's interesting to study them because they may have a comparison to today. He added, I think it is certainly extremely significant that a lot of the main crises of the past are associated with global warming, with obvious implications for the present day.