4.3 Comparing the physical content

SimClimat has a much simpler physical content than the climate models participating in CMIP (table 2), which allows it to be much faster. It represents the atmosphere in a much coarser way (0D instead of 3D), but couples more components, notably the ice sheets and the carbon cycle. To this extent, it is rather analogous to a model Earth system (figure 15, purple frame). This allows SimClimat to represent climate changes at geological time scales.

Table 2: Table identifying the main differences between climate models participating in CMIP and SimClimat's physical model.

Models	Climate model participating in CMIP	SimClimat
Atmospheric grid dimension	3D	0D
Atmospheric and oceanic dynamics	yes	no
Time steps	a few seconds or minutes	several years
Radiation and Earth radiative balance	yes	very simple
Cloud effects	yes	no
Carbon cycle	no	yes
Ice sheets	no	yes
Uncertainty estimate	iner-model spread	no
Computational time for 100 years	several days	less than a second