> After all, if this is possible and the earth has been much warmer, why hasn’t this happened already? We have two large-scale extinction events on record that

> After all, if this is possible and the earth has been much warmer, why hasn’t this happened already? We have two large-scale extinction events on record that may have been caused by or exacerbated by global warming: Tirassic-Jurassic Extinction event, and the Paleocene–Eocene Thermal Maximum (more a series of small-scale extinction events than a single large one). In world-scale timelines, humans haven't been around that long. > I just don’t believe we’re that close to a tipping point. Climate is complicated and the earth can’t have been livable for billions of years without some balancing factors, right? It wasn't. We've had many extinction level events. Humanity should be concerned about not becoming one.