1. Sure we have values for earlier periods, estimated through abundant and reliable (in its own way) geologic evidence. But you don't even need to bo back furth

1. Sure we have values for earlier periods, estimated through abundant and reliable (in its own way) geologic evidence. But you don't even need to bo back further than 100 years to see how wildly our climate is whiplashing right now. 2. Yes, which is why climate scientists put lots of error bars on their predictions and document carefully the assumptions they're making. To wit, the assumption that we will continue to be as bone-headed about our impact on these systems as we have been. But it is still the case that I have little idea what the weather will be in my back yard in 3 mos but a pretty good idea of what global mean temperature we're looking at in 5 years.