Earth system model of intermediate complexity CLIMBER-2 (retired)

CLIMBER-2 is an Earth-system model of intermediate complexity (EMIC)  for long-term and paleo-climate simulations developed at PIK by a group of scientists under the leadership of A. Ganopolski. The model includes the 2.5-dimensional statistical-dynamica atmospheric model , a 2‐dimensional 3-basin ocean model and the 3-dimensional polythermal ice-sheet model  SICOPOLIS, dynamical terrestrial vegetation model, ocean carbon, aeolian dust and other components.


The model has been developed at PIK since 1995. Initially it includes only climate components: atmosphere, ocean and land surface processes (Petoukhov et al., 2000). Late the dynamical vegetation model VECODE and ice sheet component SICOPOLIS have been incorporated. Model development continued till 2017 The final version of the model included also ocean carbon cycle component suitable for very long-time scales, permafrost, aeolian dust cycle.

From the beginning, the model has been used both for future and past simulations. In particular, CLIMBER-2 has been used for simulations of LGM and Holocene climates, Dansgaard-Oeschger and Heinrich events as well as Quaternary glacial cycles. The final application of the model was simulation of climate evolution during the entire Quaternary (Willeit et  al., 2019). Currently, a much more advanced and high-resolution model of the same class – CLIMBER-X – has been developed and tested to continue study of the long-term evolution of the Earth system.

Principal structure of CLIMBER-2 (by A. Ganopolski)


Model description and validation

Petoukhov V., A. Ganopolski, V. Brovkin, M. Claussen, A. Eliseev, C. Kubatzki, and S. Rahmstorf (2000)  CLIMBER-2: a climate system model of intermediate complexity. Part I: model description and performance for present climate.  Clim Dynam 16, 1-17

Ganopolski, A., V. Petoukhov, S. Rahmstorf, V. Brovkin, M. Claussen, A. Eliseev, and C. Kubatzki (2001) CLIMBER-2: a climate system model of intermediate complexity. Part II: Model sensitivity, Climate Dynamics, 17, 735-751.

Brovkin, V., J. Bendtsen, M. Claussen, A. Ganopolski, C. Kubatzki, V. Petoukhov, and A. Andreev (2002) Carbon cycle, vegetation and climate dynamics in the Holocene: Experiments with the CLIMBER-2 model. Global Biogeochemical Cycles, 16(4), 1139.

Calov, R., A. Ganopolski, M. Claussen, V. Petoukhov, and R. Greve (2005) Transient simulation of the last glacial inception with an atmosphere-ocean-vegetation-ice sheet.  Part I: Glacial inception as a bifurcation of the climate system. Climate Dynamics 24, 545-561.

Ganopolski, A., R. Calov, and M. Claussen (2010) Simulation of the last glacial cycle with a coupled climate ice-sheet model of intermediate complexity. Climate of the Past, 6, 229-244.

Bauer, E. and Ganopolski, A. (2014) Sensitivity simulations with direct shortwave radiative forcing by aeolian dust during glacial cycles. Climate of the Past, 10, 1333–1348.

Willeit, M. and Ganopolski, A (2015) Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle. Climate of the Past, 11, 1165–1180.

Main publications

Ganopolski, A., S. Rahmstorf, V. Petoukhov, and M. Claussen (1998) Simulation of modern and glacial climates with a coupled global model of intermediate complexity, Nature, 391, 351-356.

Ganopolski, A., and S. Rahmstorf  (2001) Rapid changes of glacial climate simulated in a coupled cli­mate model. Nature, 409, 153-158.

Calov, R., A. Ganopolski, V. Petoukhov, M. Claussen, and R. Greve (2002) Large-scale instabilities of the Laurentide ice sheet simulated in a fully coupled climate-system model. Geophys. Rev. Lett., 29, 2216.

Haug G.H., A. Ganopolski, D.M. Sigman, A. Rosell-Mele, G.E.A. Swann, R. Tiedemann, S.L. Jaccard, J. Bollmann, M.A. Maslin, M.J. Leng, and G. Eglinton  (2005) North Pacific seasonality and the glaciation of North America 2.7 million years ago. Nature, 433, 821-825.

Ganopolski, A, Calov R. (2011) The role of orbital forcing, carbon dioxide and regolith in 100 kyr cycles. Climate of the Past, 7,  1415–1425.

Ganopolski, A., Brovkin, V. (2017) Simulation of climate, ice sheets and CO2 evolution during the last four glacial cycles with an Earth system model of intermediate complexity. Climate of the Past, 13, 1695–1716.

Willeit, M., Ganopolski, A., Calov, R., Brovkin, V. (2019). Mid-Pleistocene transition in glacial cycles explained by declining CO2 and regolith removal, Science Advances, 5: eaav7337.