30 Gigatons of Carbon per Year

[Consider the] Paleocene-Eocene Thermal Maximum, which was about 55 million years ago. During that period, there was a mass extinction - it's not one of the Big Five, so it’s not at the same scale of the end of the dinosaurs, for example - but it still led to the loss of up to 50 percent of marine species in some groups of organisms. The difference is that at that time it’s estimated, through natural causes, just over two gigatons of carbon was being pumped into the atmosphere per year for several thousand years. Now we are pumping 30 gigatons of carbon into the atmosphere per year. So that’s why what’s happening now is so extraordinary - it's simply the rate at which this is occurring.