The One Health approach has moved from the margins of global health into the mainstream as climate change reshapes the conditions in which people, animals, and ecosystems coexist. Rising temperatures, environmental degradation, and accelerating urbanization are no longer distant risks but active forces shaping public health outcomes today. In 2024, global temperatures exceeded 1.5 degrees Celsius above pre industrial levels across a full calendar year, marking a historic climate threshold. This warming is not abstract.