This has always happened.

Climate change over geologic time is, Laughlin says, something the earth has done “on its own without asking anyone’s permission or explaining itself.” People can cause climate change, but major glacial episodes have occurred “at regular intervals of 100,000 years,” always “a slow, steady cooling followed by abrupt warming back to conditions similar to today’s.”

Six million years ago the Mediterranean dried up. Ninety million years ago there were alligators in the Arctic. Three hundred million years ago Northern Europe was a desert and coal formed in Antarctica. “One thing we know for sure,” Laughlin says about these convulsions, “is that people weren’t involved.”

I've been saying this for years.