Question

Is this really possible that a global civilization on par with current one could have existed on earth?

Answer 1

The canonical example of a hyperthermal is the Paleocene–Eocene Thermal Maximum (PETM), a 200,000-year period that occurred some 55.5 million years ago when global average temperatures rose by 5 to 8 degrees Celsius (about 9 to 14 degrees Fahrenheit). Schmidt has pondered the PETM for his entire career, and it was on his mind one day in his office last year when the University of Rochester astrophysicist Adam Frank paid him a visit.