HR: 16:15h
AN: PP54B-02    [Abstracts]
TI: Did the Climatic Response Skip a Precessional Beat During Marine Isotope Stage 11?
AU: * Mueller, U C
EM: ulrich.mueller@em.uni-frankfurt.de
AF: Institute of Geology and Paleontology, Johann Wolfgang Goethe University Frankfurt Senckenberganlage 32-34 , Frankfurt, 60054 Germany
AU: Kotthoff, U
EM: ulrich.kotthoff@em.uni-frankfurt.de
AF: Institute of Geology and Paleontology, Johann Wolfgang Goethe University Frankfurt Senckenberganlage 32-34 , Frankfurt, 60054 Germany
AU: Pross, J
EM: joerg.pross@em.uni-frankfurt.de
AF: Institute of Geology and Paleontology, Johann Wolfgang Goethe University Frankfurt Senckenberganlage 32-34 , Frankfurt, 60054 Germany
AB: The paleoclimatic development during Marine Isotope Stage (MIS) 11 is considered to be the best available analogue to the present. Variations in summer insolation at high northern latitudes (generally considered the main climate forcing) during that stage closely resemble those of the elapsed part of the Holocene and the future 50,000 years. Here we compare MIS 11 sea surface temperature records from the northeastern North Atlantic and MIS 11 pollen records from southern and central Europe with variations of summer insolation at 65°N to assess the climatic response of different environmental settings and geographic regions. During MIS 11, warm sea surface conditions as well as closed forests prevailed for an exceptionally long period. i.e. around 40,000 years, in the North Atlantic (ODP Sites 980 and 983) and in southeastern Europe (Tenaghi Philippon), respectively. This seems to support the view that the climatic response to orbital forcing skipped a precessional beat, possibly due to the muted insolation minimum that occurred at 395 ka BP during MIS 11 (McManus et al. 2003). A closer inspection of the pollen record from Tenaghi Philippon (Wijmstra & Smit 1976), however, reveals a interim phase when the percentages of thermophilous tree pollen declined to glacial values in the middle third of the exceptionally long forestation period during MIS 11. This phase, when thermophilous forests were replaced by a pine forests, matches the abovementioned muted insolation minimum. Further north, in central France, the MIS 11 pollen record from Praclaux (Reille & Beaulieu 1995) shows a decline of thermophilous and even pine-dominated forests during the insolation minimum at 395 ka BP. This forest decline marks the end of the Holsteinian interglacial in central Europe. Therefore we conclude that under natural boundary conditions even a muted insolation minimum very similar to the present orbital configuration can result in a glacial inception.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4934 Insolation forcing
DE: 4952 Palynology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005