During almost half a century, Professor Terry V. Callaghan has been active in polar research focusing on Arctic environment and the ecology of Arctic plants, animals, and ecosystem processes, including ecological responses to changes in climate, atmospheric CO₂ concentrations, and UV-B radiation. Professor Callaghan is an excellent scientist who has carried out outstanding research and he is also a role model for colleagues and young scientists, and an excellent friend. Through his hard work he has made himself a strong and positive reputation within the polar community and beyond.

Professor Callaghan has contributed to and led numerous international scientific synthesizing processes. He was a member of the United Nations Environment Programme’s expert panel on Stratospheric Ozone Depletion Effects for many years (Zepp et al. 1998, 2003), he was a lead author of the Intergovernmental Panel on Climate Change Polar and Ecosystems Chapters (Anisimov et al. 2007) as well as...