While we are always changing—our cells replacing themselves, our children growing up, passing of beloved pets, places, homes and people—collectively we are entering new terrain. Our Earth, our only known home, the only known biosphere where humanity exists, crossed the 1.5 degrees Celsius threshold in February 2024. We live now in the warmest temperatures in pre-industrial recorded human history, in a world of new experiences, new dangers, and new uncertainties.