ClimateChange Assessment Guide.pdf - University of Waterloo

Guide for Assessment of Hydrologic Effects of Climate Change in Ontario20Figure 3.1 Conceptual structure of a coupled atmosphere-ocean general circulation model (Viner and Hulme, 1997)defGlobal climate model (GCM) • numericalrepresentation of the climate system based onthe physical, chemical and biological propertiesof its components, their interactions andfeedback processes, and accounting for all orsome of its known properties (Baede et al., 2007)A number of international climate modelling centresexist. Eighteen modelling groups using 21 climatemodels performed a suite of coordinated climatesimulations in the Coupled Model IntercomparisonProject Phase 3 (CMIP3); a significant contributionto the Fourth Assessment Report (AR4) of the IPCC.The formulations of these GCMs and their simulationresults are currently the most up-to-date results onthe sensitivity of the climate system to increasingconcentrations of GHGs available for climate changeimpact assessments (Intergovernmental Panel onClimate Change (IPCC), 2007c).Climate models have progressed from simpleatmosphere only models to the highly complexcoupled atmosphere-ocean general circulation models(AOGCMs) used for simulations today (Figure 3.2).Early simulations were based on atmospheric generalcirculation models (AGCMs) that had their origins innumerical weather prediction. Land surface processes,ocean general circulation models and sea-ice dynamics,and sulphate aerosol modules were added to AGCMsto develop AOGCMs. Now, ecosystem processesand the carbon cycle are being incorporated intoAOGCMs to develop Earth systems models. Advancesin GCMs have been made by adding new features;