If there was no climate catastrophe when the CO2 level was around 4,000 ppm, why is it believed there will be a climate catastrophe, now, if the CO2 level, which is currently around 500 ppm, continues to rise, or just increase a little bit more? - TL Winslow, Pansophist master of STEM and world history

https://www.quora.com/If-there-was-no-climate-catastrophe-when-the-CO2-level-was-around-4-000-ppm-why-is-it-believed-there-will-be-a-climate-catastrophe-now-if-the-CO2-level-which-is-currently-around-500-ppm-continues-to-rise-or-just/answer/TL-Winslow