Description/Abstract The nitrogen cycle plays a central role in the biogeochemistry of the ocean and is intimately linked with global climate change on interannual to glacial-interglacial timescales. Nitrogen isotopes, in turn, provide us with a means of monitoring past changes in the marine nitrogen cycle from sedimentary records. This presentation will address two fundamental questions: Are surface ocean processes affecting nitrogen isotopes faithfully recorded in deep sea sediments? What is the whole-ocean nitrogen isotope signal during the last glacial - interglacial transition telling us about changes in marine N cycling during global warming? Bio: Professor Markus Kienast is a (marine) geologist and oceanographer, spezialized in reading the biogeochemical record of past ocean and climate change preserved in the sedimentary record. Long-term goals of his research include: 1) to establish a thorough understanding of nitrogen isotope evidence for past changes in the oceanic nitrogen cycling and inventory, and 2) to understand more fully the importance of the tropical Pacific Ocean in past global climate change. Markus is a member of the Executive Committee of the Canadian Consortium for Ocean Drilling (CCOD), represents Canada at the IMPRESS program, the successor of the international IMAGES program, and is co-director of the NSERC-CREATE for Transatlantic Ocean System Science and Technology (TOSST) between Dalhousie and Kiel Unviersity/GEOMAR.