Professor of Ocean Physics at DAMTP and formerly Director of the Scott Polar Research Institute. He is a specialist on sea ice and polar oceanography and has run a research group in this area for 35 years, with a strong emphasis on field operations (he has led 43 field expeditions to the Arctic and Antarctic). His work has ranged over the properties of the marginal ice zone; the interaction of ocean waves with ice; the dynamics of icebergs; polar water masses, currents and eddies; sea ice physical properties; the mechanisms of deep ocean convection at high latitudes; and the thickness of sea ice. His main current interest is in the ice thickness distribution in the Arctic and the reasons for sea ice thinning and retreat. He has pioneered the use of AUVs (autonomous underwater vehicles) to measure under-ice topography and has worked with the Royal Navy since the 1970s in carrying out ice thickness measurement work from Navy submarines on Arctic deployments. He is a member of the Scientific Committee of the European Environment Agency, Copenhagen.