For the first time in recorded history, olive ridley sea turtles — creatures of tropical and subtropical seas — have come ashore to nest on Southern California beaches, crossing a threshold that no member of their species has crossed before. Their arrival is both a conservation milestone and a quiet testament to how profoundly warming oceans are redrawing the map of where life on Earth can take hold. Scientists and conservationists watch with cautious hope, knowing that what opens a door for one vulnerable species may signal deeper, less forgiving changes for the seas as a whole.