The WP’s Brad Plumer talks with Elizabeth Kolber about her new book, The Sixth Extinction, and the many grim portents for life on our planet these days. “I think many scientists would say that what we’re doing to the chemistry of the oceans is the most significant. One-third of the carbon-dioxide that we pump into the air ends up in the oceans almost right away, and when CO2 dissolves in water, it forms an acid, that’s just an unfortunate fact.”