Karlsruhe is becoming warmer and drier as climate changes in southwest Germany. Large city trees often become the first target for removal during infrastructure projects. At the same time, the poor vitality of city trees due to climate change impacts, diseases, and early aging of trees also sometimes contributes to the premature removal of trees. In this presentation, I will show the importance of large trees in cooling and biodiversity conservation in urban areas (e.g., streets, cemeteries, and parks) and provide some outlook on improving arboriculture and tree care so that the large trees can be kept in the city for a longer time. I will provide examples from the concluded GrüneLunge, ongoing URBORETUM, and other research projects.