WG 1: The Physical System
Coordinators:
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
- Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven
- GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Kiel
- Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ), Potsdam
- MARUM - Zentrum für Marine Umweltwissenschaften der Universität Bremen, Bremen
- Max-Planck-Institut für Meteorologie (MPI-M), Hamburg
- Potsdam-Institut für Klimafolgenforschung (PIK) e. V., Potsdam
Summary
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.
WG 2: Biogeochemistry
Coordinators:
Dr. Victor Brovkin
Max-Planck-Institut für Meteorologie,
Bundesstr. 53, 20146 Hamburg
Dr. Tatiana Ilyina
Max-Planck-Institut für Meteorologie,
Bundesstr. 53, 20146 Hamburg
Dr. Peter Köhler
Alfred-Wegener-Institut (AWI) Helmholz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen 26, 27568 Bremerhaven
Participating institutions:
1. Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven
2. Institut für Biogeochemie und Meereschemie der Universität Hamburg (UHH), Hamburg
3. Institut für Geowissenschaften der Universität Kiel (CAU), Kiel
4. MARUM - Zentrum für Marine Umweltwissenschaften der Universität Bremen, Bremen
5. Max-Planck-Institut für Chemie (MPI-C), Mainz
6. Max-Planck-Institut für Meteorologie (MPI-M), Hamburg
7. Potsdam-Institut für Klimafolgenforschung (PIK) e. V., Potsdam
Summary
Ice cores provide compelling evidence that glacial-interglacial changes in climate and greenhouse gases are tightly coupled. The long-term goal of WG2 in PalMod is to understand processes controlling this coupling and to quantify feedbacks between biogeochemistry and climate during glacial cycles using Earth System Models. In the 2nd phase, the main challenge for WG2 is to apply project ESMs for fully-coupled interactive climate-carbon cycle simulations through the last deglaciation (21 to 6 ka). Such simulations were never done before with full-scale ESMs. In addition to deglaciation runs, WG2 will also perform millennial-scale ESM simulations to analyze the carbon and CH4 cycle variability during abrupt climate events in MIS-3 and to compare them with available data together with WG3. To prepare fully-coupled interactive climate-biogeochemistry simulations through the last glacial cycle in the 3rd phase, first simulations of the glacial inception (125-110 ka) with prescribed atmospheric CO2 concentration for physics but prognostic CO2 concentration in biogeochemistry will be performed in cooperation with WG1.
Our general strategy is to use the model ensemble developed in phase 1: AWI-ESM, CESM, MPI-ESM. The principal feature of the global carbon cycle is that it strongly depends on the physical climate components: atmospheric and ocean circulations, as well as the cryosphere. Therefore, setting up the biogeochemical components (land vegetation and carbon cycle, ocean biogeochemistry) for transient simulations will be done in close interaction with WG1 packages 1.1 to 1.3. Every ESM team will prepare biogeochemistry models for the transient runs in coupled setup, when changes in land and ocean carbon fluxes simultaneously influence atmospheric CO2 concentration and, consequently, climate. A particular challenge in the 2nd phase is to couple land and ocean biogeochemical exchange in shelf regions induced by sea-level changes in co-operation with the CC.2 theme. Experiments with the two orders-of-magnitude faster EMIC CLIMBER-X will serve as a guideline for transient simulations with ESMs.
Workflow in WG2 is structured along biogeochemical components, and three WG2 packages are focused on the marine carbon cycle, terrestrial and shelf processes, and the CH4 cycle.
WP2.1 Marine Carbon Cycle
Principal Investigators: P. Köhler (AWI), T. Ilyina (MPI-M), B. Schneider (CAU), A. Paul (MARUM)
Setting up biogeochemical simulations with prognostic atmospheric CO2 concentration in all three ESMs is a first task for WP2.1. This work includes adjustment of initial inventories, a coupling of land- ocean carbon exchanges due to sea level changes, as well as accounting for weathering fluxes and volcanic outgassing. Simulations done together with WP1.1 will be evaluated against available data estimates and additional sensitivity simulations will be performed. Carbon isotopes will help to identify which changes in the physical system agree with reconstructions. Here, 14C can and will also be used in simulations without interactive carbon cycle, as done before (Butzin et al., 2012), while for 13C isotopic fractionation during photosynthesis needs to be considered and therefore an interactive carbon cycle is necessary.
WP2.2 Land and Shelf Processes
Principal Investigators: A. Ganopolski (PIK), M. Claussen (MPI-M), J. Hartmann (Uni HH)
This work package takes care of biogeochemical processes on land and exposed shelves. Vegetation, desert, and land carbon dynamics during deglaciation, inception, and MIS3 will be quantified using MPI-ESM in co-operation with WG1. It will be also be utilized for AWI-ESM, and compared with available pollen data synthesized in WG3. The carbon exchange between land and ocean components on exposed shelves will be done together with CC.1. Weathering on exposed shelves will be reconstructed and -included in simulations with prognostic CO2 concentrations. WG2 will also use the EMIC, CLIMBER-X, as a fast 3-D ocean model prototype to test hypotheses on processes behind deglacial CO2 rise and CO2 decrease during glacial inception.
WP2.3 Methane Cycle
Principal Investigators: T. Kleinen (MPI-M), B. Steil (MPI-C)
The main challenge in the CH4 work package is to simulate atmospheric CH4 concentrations in a concert between terrestrial CH4 emissions (mostly from wetlands) and the atmospheric methane sink using the MPI-ESM model asynchronously coupled to the atmospheric chemistry model EMAC. We will investigate CH4 dynamics during the deglaciation, glacial inception, and MIS3. A number of hypotheses will be tested using available CH4 data and the atmospheric isotopic composition of different chemical tracers. Abrupt changes in atmospheric CH4 concentrations during abrupt climate events in MIS3 will be addressed together with WP1.3.
While results during phase 1 do not indicate any major risks from the CH4 modelling itself, CH4 emissions are critically dependent on correct terrestrial C pools and fluxes (i.e. atmospheric CO2 concentrations). In case these cannot be provided by WPs 2.1 and 2.2, the fall back option of driving the model with prescribed CO2 will be required.
WG 3: Datasynthesis
Coordinators:
Dr. Stefan Mulitza
MARUM - Zentrum für Marine Umweltwissenschaften der Universität Bremen, Leobener Strasse, 28359 Bremen
Prof. Dr. Ulrike Herzschuh
Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung, Telegrafenberg, Potsdam
Participating institutions:
1. MARUM - Zentrum für Marine Umweltwissenschaften der Universität Bremen, Bremen
2. Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven and Potsdam
3. Helmholtz-Zentrum Potsdam – Deutsches GeoForschungsZentrum (GFZ), Potsdam
4. Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
Summary
Proxy data are key to validate the comprehensive ESMs used in WG 1 and 2. The aim of WG3 is to generate a quality-controlled synthesis of quantitative proxy records from the marine and terrestrial realms. This synthesis will allow to diagnose individual aspects of the model simulations (ocean circulation, ocean biogeochemistry, hydrological cycle, land cover and vegetation and the pattern of climate variability) in CC.2. In the 2nd phase, the existing effort in the synthesis of proxy time series will be extended from the last 40,000 years to the entire last glacial-interglacial cycle. In addition to the extension of proxy data sets created in Phase I, novel types of proxy data of particular relevance to WG1 will be compiled in Phase II, including ice-sheet distribution and stable isotope data from lake sediments. To advance the proxy-model-comparison in cooperation with CC.2, WG3 will particularly focus on modelling the processes of proxy formation (i.e. habitat effects of proxy-signal carriers) and the processes that distort primary signals in climate archives (i.e. bioturbation). The application of proxy models will result in improved estimates of the spectrum of climate variability and more realistic proxy error margins, needed for a meaningful model-data comparison in CC.2. The evaluation of climate model results against robust paleoclimatic evidence is essential to inform our confidence into future climate projections by the same models.
WP3.1: Marine proxy-data syntheses and reconstructions
Principal Investicators: M Kucera (MARUM), S. Mulitza (Uni Bremen)
Working package 3.1 aims to complete the synthesis of climate-system relevant marine paleoenvironmental data, and transform these datasets into data products that can be used for a comparison with the output of model experiments performed in WG1 and WG2 through the data- model comparison toolbox developed in CC.2.
WP3.2: Terrestrial and ice sheet proxy-data syntheses and reconstructions
Principal Investicators: A. Brauer (GFZ), U. Herzschuh (AWI), L. Tarasov (Memorial Uni St. John's, Canada)
The overarching goal of work package WP3.2 is a quantitative and qualitative climate reconstruction based on process-based multiproxy interpretation from terrestrial records for model-data comparison.
WP3.3: Integrative forward proxy modelling
Principal Investicators: M. Werner (AWI), T. Läpple (AWI), A. Paul (MARUM)
The overarching goal of work package WP3.3 is to enable a quantitative and process-oriented model- proxy comparison linking modeling efforts performed within WG1 with data syntheses provided by WG3 and the tools and concepts of model-data comparison provided by CC. These efforts will particularly focus on stable water isotope data (δ18O, δD), but will also include planktonic foraminiferal abundances.
CC: Crosscutting Activities
Coordinators:
Dr. Kira Rehfeld (CC2)
Universität Heidelberg, Institut für Umweltphysik, Im Neuenheimer Feld 229, 69120 Heidelberg
Dr. Hendryk Bockelmann (CC1)
Deutsches Klimarechenzentrum, Bundesstr. 45a, 20146 Hamburg
Participating institutions:
1. Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven (AWI)
2. Institut für Informatik, Christian-Albrechts-Universität zu Kiel, Kiel (CAU)
3. Deutsches Klimarechenzentrum GmbH, Hamburg (DKRZ)
4. GEOMAR Helmholtz-Zentrum für Ozeanforschung, Kiel
5. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung GmbH, Geesthacht (HZG)
6. Max-Planck-Institut für Meteorologie, Hamburg (MPI-M)
7. Potsdam-Institut für Klimafolgenforschung e.V., Potsdam (PIK)
8. Institut für Geowissenschaften und Meteorologie, Universität Bonn (UBonn)
9. Institut für Umweltphysik, Ruprecht-Karls-Universität Heidelberg (UHD)
Summary
Crosscutting Activities (CC) in PalMod phase II create a platform that is dedicated to research and services to support and connect the working groups 1-3. Fig. 1 (part I of the Pre-Proposal) depicts the overall structure of CC and their linkages to the other work packages. The work proposed in CC will on the one hand help to advance the modelling efforts and on the other hand yield insight into the interpretation and evaluation of the model results. The two major aspects that CC will cover are development and optimization of the models or model components used in PalMod (CC.1), and data management, model-data evaluation & hypothesis testing (CC.2). These are essential research activities and overarching building blocks for the success of PalMod. They are particularly important for model development and optimization tasks of the project because they will enable the ambitious simulation of a full Glacial cycle, as well as for the model-data evaluation and the hypothesis testing connected to these simulations.
CC.1 Model coupling and runtime optimisation
Principal Investigators: H. Bockelmann (DKRZ), D. Barbi (AWI), NN (MPI-M), T. Slawig (CAU), R. Winkelmann (PIK)
To reach the overall project goals by improving model capabilities and runtime, CC.1 will focus on the dynamic coupling of processes that take place at the interface between land/ice sheets and the ocean in simulations with dynamic and transient boundary conditions, particularly for paleo-lakes, continental shelves and ice shelf cavities. For the implementation aspect of the models we aim for higher computational throughput of the full Glacial cycle simulation at coarse and low resolution by improved parallelism and adaption of the source code to recent and upcoming HPC architectures.
CC.2 Data Management & Model-Data Comparison
Principal Investigators: H. Thiemann (DKRZ), K. Rehfeld (UHD), O.Bothe (HZG), A. Hense (U Bonn), NN (GEOMAR)
To facilitate the data management and the data-model intercomparison, CC.2 aggregates and standardizes the modl output of the ESMs. Furthermore, it is responsible for the data stewardship of the proxy syntheses, and provides a centralized location for model intercomparison, simulation archiving and publication. Moreover, new metrics and tools will be developed to compare model and data within PalMod, which enables evaluation of the simulations, and the testing of the key hypotheses on Glacial-interglacial climate dynamics.