With tipping points and extreme global warming looming, the key to understanding our climate future lies in our distant past With rising emissions, we are on track to cause rapid global warming with devastating consequences. But how bad could climate change get and what might it do to planet Earth and humanity? Runaway Climate explores the causes of the Paleocene Eocene Thermal Maximum (PETM) rapid climate-heating episode, its dramatic impact on life on Earth, and lessons for our climate future.