A myriad of physical processes, spanning scales from centimeters to hundreds of kilometers, contribute to the ocean circulation. Improvements in observational techniques as well as numerical models are just now allowing us to develop and test theories on how the ocean mesoscale, lengths scales of tens of kilometers and times scales from days to weeks, influence the global circulation. The ocean mesoscale is dominated by coherent structures, such as eddies and jets, which are important for the stirring and distribution of ocean properties such as temperature and salinity. Improved understanding of how the ocean mesoscale mediates the circulation's response to changing atmospheric forcing can help us to better model past and future climates. My research uses a combination of sea-going observations, idealized numerical models and theory to study how the ocean mesoscale influences the transport of heat, chemicals and biology in the ocean and how this transport in turn impacts global climate. I am especially interested in Southern Ocean dynamics, which is a key part of the global circulation both for the formation of unique water masses and for exchange between different ocean basins.