A 2017 Netflix documentary on “coral bleaching” or the die off of 25% of the world’s coral reefs during one year documented with time-lapse photography. Corals are a symbiosis of a colonial animal and photosynthesizing algae, zooxanthellae. Like our cities, coral reefs can only survive over a range of temperature. When the temperature of the oceans exceeds the limit, the algae and the coral animals die. A disturbing wake up call about the massive 6th extinction that is now being driven by anthropogenic global heating.