8.2.4 Cryospheric Processes

8.2.4.1 Terrestrial Cryosphere

Ice sheet models are used in calculations of long-term warming and sea level scenarios, though they have not generally been incorporated in the AOGCMs used in Chapter 10. The models are generally run in ‘off-line’ mode (i.e., forced by atmospheric fields derived from high-resolution time-slice experiments), although Huybrechts et al. (2002) and Fichefet et al. (2003) reported early efforts at coupling ice sheet models to AOGCMs. Ice sheet models are also included in some EMICs (e.g., Calov et al., 2002). Ridley et al. (2005) pointed out that the time scale of projected melting of the Greenland Ice Sheet may be different in coupled and off-line simulations. Presently available thermomechanical ice sheet models do not include processes associated with ice streams or grounding line migration, which may permit rapid dynamical changes in the ice sheets. Glaciers and ice caps, due to their relatively small scales and low likelihood of significant climate feedback at large scales, are not currently included interactively in any AOGCMs. See Chapters 4 and 10 for further detail. For a discussion of terrestrial snow, see Section 8.3.4.1.