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.
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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): http://onlinelibrary.wiley.com/doi/10.1002/asl.316/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false
More details about the project can be found here: http://climate.envsci.rutgers.edu/GeoMIP/index.html
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: peter.irvine@iass-potsdam.de and ben.kravitz@pnnl.gov.