Since Serengeti-scale savanna ...

Since Serengeti-scale savanna scenes are only one or two million years old, our earliest after-the-apes ancestors didn't move into this scene so much as they evolved with it, as the slower climate changes and uplift produced more grass and less forest.
 William H. Calvin

Quotes from the same author

Climate change has a very high procrastination penalty that just grows with each passing year of inaction - rather like what happens if you don't pay off your credit card. But for climate, there is no such thing as a fresh start from bankruptcy.
 William H. Calvin
The real focus needs to be on political action to stop this runaway train, real soon.
 William H. Calvin