Hans-Otto Poertner is a researcher in marine ecophysiology. He has established theory and evidence on effects of climate warming, ocean acidification, and hypoxia on marine animals and ecosystems. His efforts focus on linking biogeography and ecosystem functioning to molecular, biochemical and physiological mechanisms shaping organism tolerance and performance. In October 2015 he was elected Co-Chair of IPCC Working Group II for its 6th assessment cycle. He is an elected member of the European Academy of Sciences, the German Advisory Council on Global Change and a Web of Science highly cited researcher 2018 onward.