A seminar course focussing on ways that the Earth's biosphere (terrestrial and marine) has altered the overall functioning of the Earth System over geological time, including (1) influence of terrestrial vegetation on surface processes such as palaeosol development, river geomorphology, erosion, and cycling of major biogeochemical nutrients on land, (2) influence of the marine biosphere on the concentration of O2 and CO2 in the atmosphere, including the origin of the stratospheric ozone layer, and (3) the interactive influence of the terrestrial and marine biosphere on atmospheric moisture transport, production of latent relative to sensible heat fluxes, and the development of the planetary boundary layer. Offered in alternate years.