WASP is an efficient Earth system model, used to make projections about future atmospheric warming, surface ocean acidification and global mean sea levels. A full description of the WASP model is given in a publication in Climate Dynamics (Goodwin, 2016), with the sea level rise component described in a publication in Earth’s Future (Goodwin et al, 2017).

WASP calculates flows of heat and carbon around the atmosphere, ocean and land (vegetation and soil) systems in response to changes in atmospheric forcing, for example rising carbon dioxide concentrations. WASP contains an 8-box representation of the atmosphere-ocean-land system, and is driven by a an equation relating global mean surface temperatures to carbon emissions derived by a study in Nature Geoscience (Goodwin et al, 2015).

WASP calculates changes in global mean sea level through two processes. First, WASP simulates the sea level rise component from the expansion of the ocean as it warms. This thermal expansion contribution to sea level rise is calculated from the simulated flow of heat into the ocean. Second, WASP simulates the sea level rise from the melting of land ice. Melting land ice causes more water to enter the ocean, which raises sea levels. WASP projects the melting of land ice component of sea level rise by using a semi-empirical coefficient to convert the warming of global mean surface air-temperatures into a rate of sea level rise from ice melting.

WASP calculates the change in surface ocean pH by considering the flows of carbon dioxide between the atmosphere and surface ocean, and the subsequent flows of carbon between the surface ocean and the deeper ocean below.