A largely invariant marine dissolved organic carbon reservoir across Earth's history

Dissolved organic carbon (DOC) is the largest pool of reduced carbon in Earth's oceans, and changes in the size of this carbon reservoir can substantially impact atmospheric oxygen and carbon dioxide levels. It is widely believed that the marine DOC pool was large for most of Earth's history, buffering the ocean-atmosphere system against oxygenation and allowing for very large perturbations to Earth's carbon cycle. A new mechanistic model of oceanic DOC cycling suggests no substantial change in the size of the marine DOC pool throughout Earth's history. These results cast new light on the potential role of marine DOC in modulating Earth's ocean and atmosphere composition and in the evolution of the earliest complex life.