Trevor McDougall is recognized as the foremost world authority on many aspects of oceanic mixing and has significantly influenced modern understanding of the subject. He has discovered four new oceanic mixing processes and has pioneered the concept of neutral surfaces along which the strong lateral mixing processes occur. McDougall has discovered and parameterized the contribution of ocean eddies to mean advection. This extra advection leads to a dramatic improvement in the ability of ocean models to simulate today's climate, and significantly, it halves the "thermal flywheel" effect of the ocean in opposing changes to the climate system. Over the past ten years McDougall has also made important contributions to almost every other aspect of ocean mixing, including double-diffusive interleaving, boundary mixing and the interpretation of microstructure data.