Daniel Conley

Chemical weathering of silicate rocks redistributes major, minor and trace elements through coupled dissolution–precipitation reactions. These weathering processes drive shifts in ocean acid–base chemistry, modulating atmospheric carbon dioxide levels and providing a stabilizing feedback in the carbon cycle. Silicate weathering occurs in both terrestrial and marine environments, releasing (‘forward’) or consuming alkalinity (‘reverse’), but these have largely been perceived as independent and studied in isolation. However, weathering products are transported downstream across terrestrial and to marine environments, suggesting a dynamic coupling of these weathering processes across scales. Here we propose that the Earth’s silicate weathering occurs along a continuum linking mountains to the deepest sedimentary environments and forward to reverse weathering. In this framework, the magnitude and direction of a local weathering flux depends on the materials’ origin, weathering–erosion history and environmental conditions. Consequently, global silicate weathering fluxes and the long-term carbon cycle feedback may be governed by the dynamic interplay of various environments along the silicate weathering continuum.