CLIMBER-2 is an Earth-system model of intermediate complexity for long-term and  paleo-climate simulations. It is based on the 2.5-dimensional statistical-dynamica atmospheric model Potsdam, a 2‐dimensional 3-basin ocean model and the 3-dimensional polythermal ice sheet model  SICOPOLIS.



We have succeeded in simulating eight full ice age cycles with prescribed CO2 concentration using CLIMBER‐2. Preliminary simulations driven only by orbital cycles (with predicted greenhouse gas changes show that glacial cycles during the Quaternary (the last 2.6 million years) represent a strongly nonlinear response of the climate‐cryosphere system to astronomical forcing; aeolian dust, CO2 and other GHGs provide positive feedbacks which amplify glacial cycles, and the removal of terrestrial sediments by the ice sheets can explain the transition from short (41,000 yrs) to long (100,000 yrs) cycles around 1 million years ago. CO2 evolution during the last glacial cycle has been successfully explained as a succession of key physical and biogeochemical processes (Brovkin et al. 2012). Furthermore, we have demonstrated the mechanisms that lead to the vexing phase relationship of CO2 lagging temperature in Antarctic ice cores (Ganopolski & Roche 2009).

Orbital forcing is important during the mid‐Pliocene warm period. Transient climate simulations for the mid‐Pliocene (3.3‐3.0 million years ago) with CLIMBER‐2 agree best with reconstructions for the warmest periods during orbital cycles (Willeit, Ganopolski & Feulner 2013). This could imply a bias toward higher values for estimates of equilibrium climate sensitivity based on mid‐Pliocene proxies.

Principal structure