Ingeborg Levin worked at the Institute of Environmental Physics at Heidelberg University and headed the working group on carbon cycle research there until her retirement in 2019. She carried out outstanding pioneering work on the use of isotope information, established the radiocarbon method for determining fossil carbon dioxide concentrations and played a leading role in setting up the European research infrastructure ICOS. In 2020, she was awarded one of the highest honours of the European Geosciences Union, the Alfred Wegener Medal, for her pioneering research. With Ingeborg Levin, we lose a scientist, colleague and teacher who advanced her research with admirable clarity and conviction and inspired generations of students. We will remember her with warmth and respect.