Simulations of the Last Millennium with a General Circulation Model Institut für Küstenforschung I f K Simulations of the Last Millennium with a General Circulation Model Hans von Storch & Martin Widmann Institut für Küstenforschung GKSS Forschungszentrum, Geesthacht and the LMM Working Group within KIHZ DEUQUA, 29.8.2002 Potsdam 08:55 - 09:20 von Storch, Hans & Widmann, M.: Simulations of Paleoclimate with General Circulation Models DEUQUA, 29.8.2002 Potsdam

Institut für Küstenforschung Quasi-realistic climate models I f K Quasi-realistic climate models Components of the climate system. (Hasselmann, 1995)

Different ways of running the model Institut für Küstenforschung I f K Different ways of running the model

Positive analog Neutral analog Application

Institut für Küstenforschung validation I f K validation 1880–2049 ECHAM3/LSG 1973–1993 ERA ECMWF

Free Simulation: 1000 years no solar variability, no changes in greenhouse gas concentrations, no orbital forcing Institut für Küstenforschung I f K Temperature (at 2m) deviations from 1000 year average [K] Zorita, 2001 Model as a constructive tool

Forced Simulation 1550-2000 simulation Changing solar forcing and time variable volcanic aerosol load; greenhouse gases

Institut für Küstenforschung I f K

Institut für Küstenforschung I f K

The Late Maunder Minimum (LMM) is the coldest phase of the so-called ‘Little Ice Age’ with marked climatic variability over wide parts of Europe. 1675-1710 vs. 1550-1800 Reconstruction from historical evidence, from Luterbacher et al. Temperature conditions in Switzerland according to Pfister‘s classification. From Luterbacher, 2001

Late Maunder Minimum 1675-1710 vs. 1550-1800 validation Reconstruction from historical evidence, from Luterbacher et al. Late Maunder Minimum Model-based reconstuction 1675-1710 vs. 1550-1800

Baltic Sea ice winter index after Koslowski (1998) grey: Index, red: 5 year mean, blue:20 year mean

Lake Sediments From Lake Holzmaar magnetic susceptibility = clastic input? Dryer winters? Proxies from lacustrine sediments of Lake Holzmaar: magnetic susceptibility, water content, TOC and 13C (from top to bottom). Available evidence from Lake Holzmaar sediment converge into a LMM scenario characterized by cooler and dryer winters and temperate to cooler summers in Europe. Effects for the lake are the reduction of clastic input, a shortening of the growing season for lacustrine algae due to the extension of the lake`s winterly ice cover and moderate summer water temperatures. ·        Magnetic susceptibility is a good approximation for clastic input into the lake basin. Lower values, as found during the LMM (Figure 6) thus possibly indicate reduced erosion in the catchment of the lake. ·        Contents of water and total organic carbon (TOC) in the sediments can be related to higher primary production in the lake. However, these parameters are subject to a concentration effect when clastic input is reduced. ·        Reduction of d13C values during the LMM suggests a massive disturbance of the lakes ecosystem. The isotope reaction is possibly an effect of a reduced growing season due to an extension of winterly ice cover or cooler summer temperatures. However, the abrupt isotope reaction at 1675 can also be interpreted as a nonlinear response of the composition of the algal community. The diatom species Aulacoseira subarctica was abundant during the LMM, while it did not occur during the reference period (Kumke et al., this volume). The present-day occurrence of this diatom is restricted to northern or alpine lakes. Conditions under which this species lives include low light supply as under ice cover and turbulent waters. Reduced growing season? 13C + Aulacoseira subarctica

Institut für Küstenforschung I f K Global 1675-1710 temperature anomaly Model as a constructive tool

Institut für Küstenforschung Model as a constructive tool I f K Model as a constructive tool Simulated differences of ice coverage, in percent, during the LMM event 1675-1710 and the long term mean 1550-1800.

Corals Off Madagaskar variations in mean annual coral d18O From Jens Zinke annual coral growth rate

Ice Cores From Greenland and Antarctica North Greenland Stacked isotope record from five North-Greenland ice cores (Schwager, 2000) Reconstruction of solar variability, deduced from 10Be measurements (Crowley, 2000) Antarctica a) Stacked isotope record from five North-Greenland ice cores (Schwager, 2000) b) Reconstruction of solar variability, deduced from 10Be measurements (Crowley, 2000) c) Stacked isotope record from three ice cores from Dronning Maud Land, Antarctica (Graf et al., in press ) Stacked isotope record from three ice cores from Dronning Maud Land, Antarctica (Graf et al., in press )

Institut für Küstenforschung Zusammenfassung: I f K Zusammenfassung: Das Klima zeigt Variabilität unabhängig von externen Antrieben und Störungen. („Rauch ohne Feuer“) Durch Vorgabe geeigneter externe Antriebe lassen sich Klimaanomalien realisieren. Ein Beispiel ist das Late Maunder Minimum. Simulationen über wenige tausend Jahre sind derzeit möglich; Simulationen über zehntausende von Jahren werden erst in einigen Jahren möglich sein .... etc ... DEUQUA, 29.8.2002 Potsdam 08:55 - 09:20 von Storch, Hans & Widmann, M.: Simulations of Paleoclimate with General Circulation Models

Institut für Küstenforschung Ausblick: I f K Ausblick: Rekonstruktion von Klimaschwankungen in den letzten paar tausend Jahren sind nicht nur von akademischem Interesse: „Detection and Attribution of Climate Change“. Das gegenwärtige (Modell-) Klima ist wärmer als alles, was wir in den letzten 500 Jahren simuliert haben. Lauf beginnend im Jahre 1000 ist „unterwegs“ und scheint in der ersten paar Jahrhunderten wärmere Bedingungen als in der zweiten Jahrtausendhälfte zu zeigen. DEUQUA, 29.8.2002 Potsdam 08:55 - 09:20 von Storch, Hans & Widmann, M.: Simulations of Paleoclimate with General Circulation Models

Institut für Küstenforschung I f K From Ulrich Cubasch

From Fidel Gonzalez-Ruoco Institut für Küstenforschung I f K From Fidel Gonzalez-Ruoco

LMM working group in KIHZ J. Zinke, C. Dullo, A. Eisenhauer - GEOMAR, Kiel H. von Storch, B. Müller, E. Zorita - Institute for Coastal Research, GKSS Research Centre, Geesthacht U. Cubasch, I. Fischer-Bruns, M&D Group at MPI of Meteorology, Hamburg B. Rein - Institute für Geowissenschaft, Universität Mainz H. B. Mieding, H. Miller, H. Fischer - Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven A. Lücke, G.H. Schleser - Forschungszentrum Jülich M.J. Schwab, J.F.W. Negendank, U. Kienel - Geoforschungszentrum Potsdam J.F. González-Ruoco - Departamento de Astrofísica y CC de la Atmósfera. UCM, Madrid Jürg Luterbacher, Bern University