This grant continues support for two years for research conducted by the Reservoirs and Fluxes community of the Deep Carbon Observatory. Led by Marie Edmonds of Cambridge University and Erik Hauri of the Carnegie Institution for Science and comprising some 120 core members across the globe, the Reservoirs and Fluxes community is engaged in a coordinated research program to advance our understanding of the volume, distribution, and movement of Earth’s carbon. Major research goals include improving our knowledge of the global budget of fluxes of gases from volcanoes; learning about carbon in the mantle and its changes through time by studying the diamonds and their inclusions that were formed very deep; improving estimates of the global circulation of carbon in Earth’s interior and fluid dynamics of carbon; and improving knowledge of the chemical forms, mineral hosts, and reactions of carbon moving between reservoirs. The third and fourth activities are key for the DCO’s program-wide initiative to build a system of models simulating the origins and movements of deep carbon through Earth’s history, the paramount synthetic effort of the DCO, which could also be its greatest scientific legacy. The majority of grant funds provide partial support for each of about ten post-docs at six different institutions.