GeoMIP was born out of a need to answer the question, "What are the expected climate effects of geoengineering?" Multiple groups in the past have conducted climate model simulations of geoengineering, but very few of them have done the same experiment, which makes it difficult to determine which features in the results are actually due to geoengineering and which are specific to the model on which the simulation was conducted. GeoMIP serves to organize geoengineering simulations by prescribing the experiments which all participating climate models will perform.
The first suite of GeoMIP experiments concentrates on Solar Radiation Management (SRM) schemes. This particular set of simulations contains four main experiments. More detailed specifications can be found in Kravitz et al. (2011) on the publications page. An outline of the four experiments:
Instantaneously quadruple CO2 concentrations (as measured from preindustrial levels) while simultaneously reducing the solar constant to counteract this forcing.
In combination with 1% CO2 increase per year, gradually reduce the solar constant to balance the changing radiative forcing.
In combination with RCP4.5 forcing, starting in 2020, gradual ramp-up the amount of SO2 or sulfate aerosol injected, with the purpose of keeping global average temperature nearly constant.
In combination with RCP4.5 forcing, starting in 2020, daily injections of a constant amount of SO2 at a rate of 5 Tg SO2 per year at one point on the Equator through the lower stratosphere (approximately 16-25 km in altitude). These injections would continue at the same rate through the lifetime of the simulation.