It’s official: Climate change has claimed its first mammal extinction.

This week the Australian government declared the extinction of a tiny rodent called Bramble Cay melomys (also known as the Bramble Cay mosaic-tailed rat, Melomys rubicola). The quiet announcement was buried in a press release about enacting stronger protections for other endangered species. It comes three years after a more detailed declaration by the state government of Queensland, which itself followed an exhaustive search of the cay seeking any evidence of the species’ existence.

The Bramble Cay melomys lived in just a single habitat, a small reef island at the northern tip of the Great Barrier Reef, near…