Information about the Geoengineering Model Intercomparison Project (GeoMIP)

Posted on June 28, 2013

A little while ago we have been approached by members of the Geoengineering Model Intercomparison Project (GeoMIP). They are interested in including a component on the effects of geoengineering on impacts. While this is not a focus of ISI-MIP, it is no doubt a very interesting and worthwhile effort and therefore we would like to forward you here the enquiry by Peter Irvine and Ben Kravitz. If you are interested, please get in touch with them directly! You will find their email addresses below.


The Geoengineering Model Intercomparison Project (GeoMIP) is a framework providing standardized experiments for all participating modeling groups.  Replicating the approach of other model intercomparison projects, such as the Coupled Model Intercomparison Project Phase 5 (CMIP5), which has greatly influenced the state of climate knowledge as reported in the upcoming Fifth Assessment Report of the Intergovernmental Panel on Climate Change, the goal of GeoMIP is to determine robust climate model response to various solar geoengineering scenarios.  Results from four experiments involving uniform solar reduction or stratospheric layers of sulfate aerosols are forthcoming, and three new experiments focused on marine cloud brightening have been proposed.  Although knowledge regarding the simulated climate effects of solar geoengineering has developed rapidly in recent years, little focus has been placed on the impacts of solar geoengineering, and hence on the benefits and risks. By using the climate model output from GeoMIP as an input to ISI-MIP models, much more could be said about the potential risks and benefits of these solar geoengineering schemes.

The four established GeoMIP experiments are
G1:  From a stable preindustrial climate, CO2 concentrations are instantaneously quadrupled, and solar irradiance is reduced to compensate for the CO2 radiative forcing.
G2:  From a stable preindustrial climate, CO2 concentrations increase by 1% per year, and the solar constant is reduced by increasing amounts to compensate for the CO2 radiative forcing.
G3:  Creation of stratospheric aerosol layers is used to offset the radiative forcing in an RCP4.5 scenario from years 2020-2069 such that top of atmosphere radiative imbalance is maintained at the same level as in the year 2020.
G4:  On top of an RCP4.5 scenario in years 2020-2069, 5 Tg of SO2 (1/4 of the amount injected by the 1991 eruption of Mt. Pinatubo) is injected into the stratosphere each year.

G2, G3, and G4 also include the termination effect:  After 50 years, solar geoengineering is abruptly ceased, and the simulation is run for an additional 20 years.

These experiments are outlined in the paper by Kravitz et al. (2011):

More details about the project can be found here:

13 GCM models have contributed to GeoMIP thus far, including some of the GCMs used in the ISI-MIP fast-track: HadGEM2-ES (all), IPSL-CM5A-LR (G1, G2, and G3), MIROC-ESM-CHEM (G4), and NorESM1-M (G1 and G2).

For more information, please email: and