Catastrophic climate change

Let's call it what it is, and it's going to get a lot worse if we don't wake up.

"[By 2100] we’ll be generating climate conditions last experienced during the Cretaceous period (145-65.95 million years ago) when CO₂ levels reached over 1,000 ppm. What might that mean? [...] In a Cretaceous rerun, there would very likely be no ice at the poles once again, and sea levels would be about 216 feet (66 metres) above current levels. We would also see the creation of vast warm shallow seas with mineral deposits similar to those that produced 1,300 ft (400 metre)-thick chalk strata in the old Cretaceous; while, in place of the larger mammals that would become extinct, reptiles might radiate across the globe and grow large in form – a fitting dinosaur revenge?"