> What about the section on the past 425 million years? Isn't that like trying to apply a physics model to the first picoseconds after the big bang? None of it makes sense to normal physics You have a timeline that includes at least five extinction level events, it even labels the start of the modern climate age (Paleogene) at 66 million years ago then CO2 was around 500ppm, which is slightly above our current 412ppm, back then the earth was all tropical humans didn't appear until ~300,000 years ago, so the only thing that's relevant here is what kind of climate are we able to survive in? which is this timeline [human period](https://pic8.co/sh/SuTT2Z.png) and here we see the regular cycles of CO2 and temperature. now we could technically survive the Paleogene because it's 4 degC hotter, but probably not in the numbers we are at now, all our agriculture would change and it's likely large areas would revert to desert. What is worrying is that this cyclical model isn't going to predict artificial increases in CO2 from industry, so the temperature might overshoot, particularly if the oceans warm up and create more water vapour