This is a new version of MAGICC/SCENGEN (version 5.3.v2) replacing version 4.1. There have been many changes, mainly to SCENGEN. These changes have been made primarily for consistency with the Working Group 1 report of the IPCC Fourth Assessment (AR4). The most important changes are:
- Historical forcings and forcing initialization values in MAGICC have been changed for consistency with AR4. Most of these changes are very small.
- The default and 90% confidence interval values for the climate sensitivity have been updated to 3.0°C (previously 2.6°C) and 1.5-6.0°C (previously 1.5-4.5°C).
- The model for calculating the sea level rise contribution from GSICs (Glaciers and Small Ice Caps) has been replaced by the physically based model of Wigley and Raper (GRL, 2005).
- The carbon cycle model in MAGICC has been modified to give a larger climate feedback, and so be in better accord with other carbon cycle models.
- The Atmosphere/Ocean General Circulation Model (AOGCM) data base in SCENGEN has been updated from CMIP2 models to CMIP3/AR4 models.
- These model data have all been regridded to 2.5x2.5 degrees latitude/longitude, so all SCENGEN map outputs are now at this finer resolution (version 4.1 data were at 5x5 degrees resolution).
- Mean sea level pressure (MSLP) data have been added to SCENGEN.
- The observed data bases (temperature, precipitation and MSLP) have been updated and regridded to 2.5x2.5 degrees latitude/longitude resolution.
- New color palette and contour interval options have been added to SCENGEN.
- A number of new AOGCM diagnostic tools have been added to SCENGEN to facilitate model selection.
MAGICC and SCENGEN are coupled, user-friendly interactive software suites that allow users to investigate future climate change and its uncertainties at both the global-mean and regional levels. MAGICC carries through calculations at the global-mean level using the same upwelling-diffusion, energy-balance climate model that has been and is employed by IPCC. SCENGEN uses these results, together with spatially detailed results from the CMIP3/AR4 archive of AOGCMs, to produce spatially detailed information on future changes in temperature, precipitation and MSLP, changes in their variability, and a range of other statistics.
In running MAGICC/SCENGEN, the user can intervene in the design of the global or regional climate change scenario in the following ways:
- By selecting and/or specifying the greenhouse gas and sulfur dioxide emissions scenarios.
- By defining the values for a limited set of climate model parameters in MAGICC that are important in determining the effects of uncertainties in the carbon cycle, the magnitude of aerosol forcing, the overall sensitivity of the climate system to external forcing, and ocean mixing rate.
- By specifying the future time period for which results are displayed (out to 2400).
- By specifying the AOGCMs that are averaged to produce the climate change pattern information.
- By selecting an area or region for spatial averaging of climate change results.
This version of MAGICC/SCENGEN was developed primarily with funding from the U.S. Environmental Protection Agency, but it rests on developments carried out over the past 20 years that were funded by a number of organizations.