An exploration of the research frontier on Earth's carbon cycle. Starting from an overview of the major reservoirs and fluxes of carbon among the atmosphere, ocean, land biosphere, and lithosphere, the course moves quickly to frontier problems, including the partitioning of anthropogenic CO₂ between the ocean and land sinks, the spatiotemporal variability of terrestrial and oceanic carbon fluxes, the role of disturbance and ecosystem dynamics, and the response of the carbon cycle to a changing climate. Modern observational datasets—including atmospheric CO₂ records, satellite retrievals of column CO₂ and solar-induced chlorophyll fluorescence, eddy-covariance measurements, as well as ship-based and float-based ocean carbon observations—are used to constrain and evaluate carbon cycle models. Through hands-on projects, students can develop, test, and critically analyze models of the carbon cycle and confront them with contemporary data. Enrollment is limited to 15 students.