Four hundred years after extinction, beavers are returning to Britain as unlikely climate heroes. Scientists reintroduced Norwegian beavers in 2009 to boost biodiversity, but discovered they're remarkably effective flood-control engineers—stopping urban flooding within weeks and creating new wetlands. However, their return has sparked fierce conflicts with farmers whose crops and salmon streams face beaver damage, revealing tensions between rewilding ambitions and agricultural livelihoods. Beavers were hunted to extinction in Britain by the 1900s for their fur, meat, and castoreum—an anal secretion used in medieval perfumes and Roman medicine.