Picture a dolphin diving toward the seafloor with something odd on its nose. It is not a shell or a fish. It is a sea sponge.

Marine heat is rising so fast that a single extra degree could push some of the ocean’s oldest animals past their limit. New work from researchers at the Australian Institute of Marine Science ...

In the new study, researchers figure that the world more than a decade ago blew past an internationally approved threshold more than a decade ago. Other scientists are skeptical of the study's claims.