Complete carbon budgets for terrestrial ecosystems must not only account for exchanges of carbon between the land and the atmosphere, but also for the movement of carbon from the land to adjacent waters including lakes, rivers and estuaries. Preliminary estimates using the Terrestrial Ecosystem Model indicate that the export of dissolved organic carbon (DOC) from terrestrial ecosystems to these water bodies may account for 15 to 27 percent of the net uptake of atmospheric carbon dioxide by contemporary land ecosystems. Thus, carbon sequestration estimates based solely on atmospheric-land fluxes will overestimate carbon storage in terrestrial ecosystems. To improve our understanding of global carbon dynamics, further studies are needed to determine the fate of DOC exported from terrestrial ecosystems.