We define the Earth Surface System (ESS) as the synergistic overlap between processes in the geosphere, the biosphere, and the climate sphere. The geosphere involves transport processes within our planet and at the surface that may ultimately result in surface-elevation changes due to tectonic deformation, erosion, or the deposition of sediments. The biosphere comprises the eco-evolutionary dynamics of organisms that drive biomass, organic ESS cover and ecosystem functions above and below the Earth’s surface. In the climate sphere, transport of ice, water, and water vapour below, at, and above the Earth’s surface is forced by global and regional radiation and energy balances.
At and near the Earth’s surface these processes interact with such strength that they cannot be fully understood when considered from the perspective of a single discipline, because the impacts across these spheres influence virtually all facets of planetary habitability.