A hangover inspired Colin Carlson to meld climate change, public health and ecology. After a night out with a parasitologist, Carlson sat at brunch asking that friend whether parasites could—like so many of the organisms he worked with—go extinct from climate change. The two went on to conduct the largest study to date of parasite biodiversity, finding that up to one third of parasite species are at risk of extinction caused by climate change. Parasites fill important niches in ecosystems...