MAGICC/SCENGEN
is a coupled gas-cycle/climate model (MAGICC) that drives a spatial
climate-change scenario generator (SCENGEN). MAGICC is a Simple Climate Model
that computes the mean global surface air temperature and sea-level rise for
particular emissions scenarios for greenhouse gases and sulphur dioxide (Raoer
et al., 1996). MAGICC has been the primary model used by IPCC to produce
projections of future global-mean temperature and sea level rise (see Houghton et
al., 2001).
SCENGEN is a database that contains the results of a large number
of GCM experiments. SCENGEN constructs a range of geographically-explicit
climate change scenarios for the world by exploiting the results from MAGICC
and a set of GCM experiments, and combining these with observed global and
regional climate data sets.
SCENGEN uses the scaling method of Santer et al.
(1990) to produce spatial pattern of change from an extensive data base of
atmosphere ocean GCM – AOGCM (atmosphere ocean general circulation models)
data. Spatial patterns are “normalized” and expressed as changes per 1°C change
in global-mean temperature. The greenhouse-gas and aerosol components are
appropriately weighted, added, and scaled up to the actual global-mean
temperature.
The user can select from a number of different AOGCMs for the
greenhouse-gas component. For the aerosol component there is currently only a
single set of model results. This approach assumes that regional patterns of
climate change will be consistent at varying levels of atmospheric greenhouse
gas concentrations.
The MAGICC component employs IPCC Third Assessment Report
(TAR) science (Houghton et al., 2001). The SCENGEN component allows users to
investigate only changes in the mean climate state in response to external
forcing. It relies mainly on climate models run in the latter half of the
1990s.
