It’s hard to know how drastically the ocean is changing if you don’t know what it’s up to in the first place. Since 1970, it has gulped down 93 percent of the excess heat and 30 percent of the carbon dioxide we’ve generated from burning fossil fuels—an extraordinary burden. As a result, it’s becoming warmer, more acidic, and less oxygen-rich. The state of ecological balance that we’re dependent on isn’t permanent: if we perturb it enough, the ocean could make things terminally unpleasant for us.
