Even under the most optimistic climate scenarios, the coming decades will see roughly 300,000 first encounters between species that normally don’t interact, leading to about 15,000 spillovers wherein viruses enter naive hosts. “It’s a little harrowing,” said Vineet Menachery, a virologist at the University of Texas Medical Branch. The study suggests that the alarming pace at which new or reemergent viruses have caused outbreaks in recent decades is not some abnormal situation, Menachery said, “but what we should be expecting, maybe even with an acceleration.”