****DRAFT REPORT FOR WGCM/AIMES**** 1 Earth System Models: The Next Generation

We are now on the threshold of including Earth system model (ESM) components in “standard” global coupled climate models used for climate change projections. At present, these standard models (referred to generically as atmosphere-ocean general circulation models, or AOGCMs) include components of atmosphere, ocean, land and sea ice. Some modeling centers have incorporated simple carbon cycle models into AOGCM’s (e.g., Cox et al. 2000, Friedlingstein et al. 2006), and additional candidate components include aerosols, chemistry, and dynamic vegetation, as discussed below. Assuming the Intergovernmental Panel for Climate Change (IPCC) Fifth Assessment Report (AR5) publication date is early 2013, modeling groups are making decisions this year (2006) on what form their next generation models will take (to be used for climate change projections). New emission scenarios have been and continue to be developed by the integrated assessment community and others (e.g. mitigation/adaptation, also referred to as stabilization). Many of these scenarios reflect the recommendations of the 25th IPCC Session (April 2006) that the following four elements should be addressed in the development of new scenarios: (1) Consistency between scenarios used for studying climate change, climate change impacts an