Astonishing as it might sound, there have been times in the past when global air temperatures increased 20 degrees C in one human lifetime. The last glaciation cycle of the Ice Age began 120,000 years ago with a Madhouse Century of seventy feet in sea level changes. The conditions then are quite similar to what they are now. So there is nothing gradual about the climate crisis. There is no "global warming" even on a human time scale.