As kids of the ’90s can attest, Bill Nye the Science Guy is a pro at explaining complicated scientific phenomena, and he does just that in a new clip on climate change with National Geographic.

There are five things we need to know to understand climate change, the science educator says — the most important being that it’s happening at an unprecedented speed.

“All this never happened this fast,” he emphasizes. “That’s what you gotta get your heads around.”

Check out the video to hear Nye break it all down.