Billions of mussels, clams, oysters, barnacles, sea stars, and other intertidal species died during the late-June heat wave in the Pacific Northwest, Christopher Harley, a zoology professor at the University of British Columbia, told me last week. Yes, that’s billions, plural. What I call “extreme, extreme heat events”—because the term extreme events doesn’t quite cover the dire situation—not only kill people; they kill plants and animals. In changing our planet’s climate, we’re permanently altering the natural world that is our life-support system. And we’re seeing this happen in real time.