Half of the world’s man-made CO2 emissions land in the ocean, where it forms carbonic acid. The oceans’ average acidity has been constant for 300 million years, until the Industrial Revolution. Over the last two centuries, it has increased by 30 percent, dropping the pH level from 8.2 to 8.1. On the 0-to-14 pH scale where anything over 7 is “alkaline” and under 7 is “acidic”. pH measurement is logarithmic so progressions can much bigger than their numbers outwardly suggest. A 0.1 drop in pH indicates a signifiant move toward acidity. If you suffer a 0.1 drop in blood pH, for instance, hold on for a seizure or a coma. Oysters in Alaska and snails off the Pacific Coast are already having trouble developing their shells. Sea urchin in the North Atlantic are producing deformed larvae. It appears that the bottom of the ocean’s food chain is already in danger, and a mass extinction event is projected for 2050. Alex argues that on top of the need to stop emitting carbon, we need to start dumping lime into the ocean (off cargo ships as they go about their business) to start raising the ocean’s pH back to 8.2.