This is the part I struggle with when I think of the massive temperature and sea level changes on a geologic time scale. The numbers that the current climate concern are dealing with (temp, sea level rise, etc.) are so tiny. How are the models controlled from the variables in the otherwise seemingly chaotic, wild swings in the lifetime of the planet? It's amazing to me that we can zoom in and make such high resolution determinations like that. I wish, as a laymen, someone could explain how we do it.