- 1Tübingen University, Department of Geoscience, Geo- and Environmental Research Center (GUZ), Tübingen, Germany
- 2Tübingen University, Department of Physics, Tübingen, Germany
- 3Max-Planck-Institute for Meteorology, Hamburg, Germany
- 4Goethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, Frankfurt, Germany
- 5Institut für Küstensysteme, Helmholtz-Zentrum Hereon, Geesthacht, Germany
- 6Deutscher Wetterdienst (DWD), Offenbach, Germany
Anthropogenic emissions are changing Earth’s global mean temperature towards levels unseen over the observational period. During the Last Interglacial (LIG) warm period, 129-116 thousand years ago, global mean temperature reached up to 1-2 degrees above preindustrial conditions, forced primarily by changes in Earth’s orbit. Both the Greenland and Antarctic Ice sheet were smaller, with sea level at least 5m, potentially up to 10m, above present levels.
The seasonal distribution of solar insolation during the LIG was characterized by higher eccentricity, obliquity, and precession leading to increased Northern, and decreased Southern Hemisphere summer insolation. Most Earth System Models included in the Palaeoclimate Model Intercomparison Project phases 3 and 4 have shown a temperature anomaly of -0.5 up to around 0.5 degrees, far lower than what has been suggested from reconstructions [Otto-Bliesner et al., 2021].
Here, we show first results from idealized equilibrium simulations with a configuration of ICON for climate prediction and projections [ICON-xpp, Müller et al 2025], varying the planetary orbit using Kepler’s solutions [Roeckner et al 2003]. We investigate the impact of different orbital forcing on global and regional temperature and precipitation mean state and variability, and discuss the impact of the choice of the land model (JSBACH vs. TERRA).
Simulating climate conditions during past warm periods, and evaluating how they compare to palaeoclimate reconstructions, improves our understanding of the Earth System, and can enhance the robustness of future projections. Our initial characterization and evaluation of orbital impacts on climate variability in ICON-xpp is therefore a crucial step towards simulating and then evaluating model performance for longer timescales, or deeper-time periods such as the Eocene, Miocene or Pliocene warmth. Moreover, using higher-resolution ICON paleoclimate simulations could provide a better basis for upcoming model-proxy data comparisons and forward modeling approaches on regional-to-local scales.
References
Otto-Bliesner, Bette L., et al. “The PMIP4 Contribution to CMIP6 - Part 2: Two Interglacials, Scientific Objective and Experimental Design for Holocene and Last Interglacial Simulations.” Geoscientific Model Development 10, no. 11 (2017): 3979–4003. https://doi.org/10.5194/gmd-10-3979-2017.
Roeckner, E., Bäuml, G., Bonaventura, L., Brokopf, R., Esch, M., Giorgetta, M., et al. (2003).The atmospheric general circulation model ECHAM 5. PART I: Model description. Report / Max-Planck-Institut für Meteorologie, 349.
Müller, W.; Lorenz, S., 2024, "Source code and scripts for publication 'The ICON-based coupled Earth System Model for Climate Predictions and Projections (ICON XPP)'", https://doi.org/10.17617/3.UUIIZ8
How to cite: Rehfeld, K., Brugger, J., Racky, M., Baudouin, J.-P., Jungclaus, J., Kelemen, F. D., Lorenz, S., Wagner, S., and Köhler, M.: First steps towards paleoclimate constraints for climate prediction and projections with the ICON model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13114, https://doi.org/10.5194/egusphere-egu25-13114, 2025.
