Scientific Info.

Most of the models used in MAGICC are described in the published literature and/or are described in the MAGICC/SCENGEN Technical Manual. A brief summary of each is given here and the relevant papers are listed. (For papers not listed below, see the Technical Manual for details.) A general description of MAGICC, its precursors ESCAPE and STUGE, and its companion software SCENGEN, can be found in Hulme et al. (1995). Version 2.4 of MAGICC/SCENGEN (January 2000) was produced for UNDP and was designed to replicate results published in the IPCC Second Assessment Report. The present version (4.x) replicates IPCC TAR results (but see the ReadMe button at the top right of the Main Menu).

The carbon cycle model employed is that of Wigley (1993). This model comprises an ocean section in which the atmosphere-to-ocean flux changes are represented as a convolution integral and a 5-box terrestrial biosphere model that is one of the hierarchy of similar models described by Harvey (1989).

The methane, nitrous oxide, and tropospheric ozone models are described in the IPCC TAR Atmospheric Chemistry chapter.

The halocarbon (and SF6) models are simple mass balance models. Lifetimes are either constant or, for species that contain hydrogen in their molecular structure, vary with changes in atmospheric OH level, paralleling changes in methane lifetime.

MAGICC considers four aspects of aerosol forcing. For details see the Aerosol Forcing section in the Model Parameters Help file. Further discussion on the handling of aerosol effects is given in Wigley and Raper (1992), Raper et al. (1996) and Wigley and Raper (2002). The primary source reference for indirect forcing is Wigley (1989).

The climate model employed by MAGICC is a standard upwelling-diffusion, energy-balance model of the form originally developed by Hoffert et al. (1980) and used by many authors since. The specific model used here is described in various papers by Wigley and Raper (1987, 1992, 1993, 2001, 2002) and by Raper et al. (1996).

The ice-melt models are those described in the IPCC TAR Sea Level chapter, with a modification to avoid spurious results for the melt contribution that may arise for simulations running beyond 2100 (see Technical Manual).

New References (not in Technical Report):