The Physical System

WG 1: The Physical System


Prof. Dr. Gerrit Lohmann

Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
Bussestr. 24, 27570 Bremerhaven


Dr. Uwe Mikolajewicz

Max-Planck-Institut für Meteorologie,
Bundesstr. 53, 20146 Hamburg


Participating institutions

  1. Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven
  2. GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Kiel
  3. Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ), Potsdam
  4. MARUM - Zentrum für Marine Umweltwissenschaften der Universität Bremen, Bremen
  5. Max-Planck-Institut für Meteorologie (MPI-M), Hamburg
  6. Potsdam-Institut für Klimafolgenforschung (PIK) e. V., Potsdam



Assessments of sea level and climate change require precise knowledge of the key processes in the Earth system. Especially the evolution of ice sheets provides a major uncertainty for past and long-term future scenarios. Within PalMod, Working Group 1 (WG1: Physical System) aims at modeling, understanding, and quantifying feedbacks during the last glacial-interglacial cycle. Based on the achievements of PalMod Phase I (e.g. incorporation of interactive ice sheets and solid earth to the climate models), we will continue to develop the physical components of our Earth System Models (ESMs). Among others, we consider and explore the effects of background climate and parameterizations addressing processes in the Southern Ocean and beneath Antarctic ice shelves. The biogeochemical components of these ESMs will be provided by WG2. In collaboration with WG2, we will conduct coordinated ESM-experiments for the time periods inception, deglaciation and the Marine Isotope Stage 3 (MIS3). These time intervals are key to understanding the Earth system dynamics during a glacial cycle. By modeling the inception and the deglaciation we can disentangle processes underlying build-up and decay of ice sheets in both hemispheres. In MIS3, we study the enhanced millennial climate variability of the last glacial. Finally, our paleoclimate simulations will be extended into the future to estimate possible climatic pathways in the next millennia.

The planned work in WG1 is organized according to the three key time periods of interest. Additionally WP1.4 focusses on key processes.


WP1.1 Deglaciation and future

Principle Investigators: G. Knorr (AWI), M. Prange (MARUM), Chr. Schannwell (MPI-M)
The overarching goal is to simulate a full deglaciation with all three model systems and the occurrence of abrupt climate events like the Boelling/Alleroed (B/A), Younger Dryas or Heinrich Event 1 (H1). Special focus will be on the underlying timing and mechanisms that trigger abrupt millennial scale variability. For each model system, simulations will be extended into the future following different prescribed scenarios, thus enabling a seamless prediction of potential long-term climate changes.

WP1.2 Marine Isotope Stage 3

Principle Investigators: U. Mikolajewicz (MPI-M), G. Lohmann (AWI), M. Prange (MARUM)
The aim of WP1.2 is an understanding of the extreme climate variability during MIS3, specifically the interplay between DO cycles and Heinrich events during MIS3 based on fully coupled transient simulations. This includes mechanisms causing DO cycles, the causation and triggering of HEs during DO stadials and the effect of HE cycles on the amplitude of DO cycles. Each model system will be used for transient simulations with interactive ice sheets spanning the period from 42 ka BP to the LGM.

WP1.3 The last glacial inception

Principle Investigators: M. Prange (MARUM), M.L. Kapsch (MPI-M), A. Ganopolski (PIK), G. Lohmann (AWI)
The process that led to the build-up of the ice sheets after the last Interglacial will be studied using our complex ESMs in combination with the EMIC CLIMBER-X. Key questions are the role of the initial state of the ice sheets in the Eemian, the role of the individual driving factors (insolation, greenhouse gas feedback) and whether a critical size of the ice Laurentide ice sheet exists that determines its survival of the insolation maximum at 105 ka. Using CLIMBER-X we will investigate, whether the ice volume growth at an early stage of glacial inception allows to predict the ice volume at later stages of the glacial cycle. This could strongly simplify the tuning of the complex climate model systems.

WP1.4 Key processes

Principle Investigators: V. Klemann (GFZ), R. Winkelmann (PIK), T. Martin (GEOMAR)
Key processes of solid earth, ice and ocean and their interaction will be investigated with a regional focus on the Southern Ocean and Antarctica. Goal is both understanding their interactions as well as improving parameterizations used in the coupled model systems with the emphasis on sub-scale as well as transient aspects. This applies to eddy-transport of heat, salt and tracers across oceanic frontal systems, ocean–ice-shelf interaction as well as the rheology of the solid earth controlling the isostatic rebound process.