The fate of Earth’s ocean

摘要

Questions of how waterarrived on the Earth’s surface, how much water is contained in the Earthsystem as a whole, and how much water will be available inthe future in the surface reservoirs are of central importance to ourunderstanding of the Earth. To answer the question about thefate of the Earth’s ocean, one has to study the global water cycle underconditions of internal and external forcing processes. Modern estimatessuggest that the transport of water to the surface is five times smaller thanwater movement to the mantle, so that the Earth will lose allits sea-water in one billion years from now. This straightforward extrapolationof subduction-zone fluxes into the future seems doubtful. Usinga geophysical modelling approach it was found that only 27% of the modern oceanwill be subducted in one billion years. Internal feedbackswill not be the cause of the ocean drying out. Instead, the drying up of surfacereservoirs in the future will be due to the increase intemperature caused by a maturing Sun connected to hydrogen escape to outerspace. style="line-height: 20px;">Keywords: Surface water reservoir, water fluxes, regassing, degassing, global water cycle