Comparison of the Holocene and Eemian paleohydrological cycle: model-data synthesis of monsoon precipitation amplitudes in key regions
Final Report Abstract
This project provides a comprehensive investigation of the development of major northern Hemisphere monsoon systems in interglacial climates (Holocene, Eemian). For this purpose a sediment core from the fluvial deposits of the Ganges-Brahmaputra-Meghna river system was analysed with regard to δD and δ13C from plant leaf waxes as proxies for continental precipitation and tracer for changes in C3 versus C4 plants, respectively. The core material was retrieved during RV Sonne cruise SO188 in the northern Bay of Bengal and during RV Meteor cruise M75 off Mozambique. It covers the time period back until 130 kyr BP. δD records indicate similarly high rainfall rates during interglacials in contrast to cold and dry glacial periods. The records of δ13C closely follow the δD record, suggesting that vegetation changes are mainly controlled by precipitation. However, the combination of climate model simulations with a simple vegetation model also highlighted an important impact of temperatures on vegetation and thus on the δ13C signal of plant waxes fossilized in marine or lacustrine sediments. The fact that δD indicates similar precipitation conditions for the Holocene and the Eemian, suggest that other factors such as atmosphere-land-ocean interactions probably also shaped rainfall and vegetation proxies during the two interglacials. Alternatively, the assumption that the leaf wax δD signal is mainly recording past conditions in atmospheric humidity is not true outside the tropical rainfall belt. This could be tested by more sophisticated model experiments including the simulation of the rainfall isotopic signature over temperate climate regions itself and by combining oxygen and hydrogen isotopologues from marine plankton with those from leaf waxes (hydrogen and carbon isotopes) extracted from marine sediments off major rivers.
Publications
- (2012): Tropical circulation and hydrological cycle response to orbital forcing. Geophys. Res. Lett., 39, L15708
Khon, V.C., W. Park, M. Latif, I.I. Mokhov and B. Schneider
(See online at https://doi.org/10.1029/2012GL052482) - (2013) Holocene changes in eastern equatorial Atlantic salinity as estimated by water isotopologues. Earth Planet. Sci. Lett., 362, 151–162
Leduc, G, J.P. Sachs, O.E. Kawka, R. Schneider
(See online at https://doi.org/10.1016/j.epsl.2012.12.003) - (2013): Northern and southern hemisphere controls on seasonal sea surface temperatures in the Indian Ocean during the last deglaciation, Paleoceanography, 28, 619–632
Wang, Y. V., G. Leduc, M. Regenberg, N. Andersen, T. Larsen, T. Blanz, and R. R. Schneider
(See online at https://doi.org/10.1002/palo.20053) - (2013): What does leaf wax δD from a mixed C3/C4 vegetation region tell us? Geochim. Cosmochim. Acta, 2
Wang Y. V., T. Larsen, G. Leduc, N. Andersen, T. Blanz, and R.R. Schneider
(See online at https://doi.org/10.1016/j.gca.2012.10.016) - (2014): Climate and CO2 effects on the vegetation of southern tropical Africa over the last 37,000 years. Earth Planet. Sci. Lett., 403, 407-417
Khon, V.C., Y.W. Wang, U. Krebs-Kanzow, J.O. Kaplan, R.R. Schneider and B. Schneider
(See online at https://doi.org/10.1016/j.epsl.2014.06.043) - (2015): Model-data synthesis of Monsoon amplitudes for the Holocene and Eemian. In: M. Schultz and A. Paul (eds.), Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC), SpringerBriefs in Earth System Science
Schneider, B., R.R. Schneider, Y. Wang, and V. Khon
- (2015): The evolution of sub-monsoon systems in the Afro- Asian monsoon region during the Holocene – comparison of different transient climate model simulations. Clim. Past, 11, 305–326
Dallmeyer, A., M. Claussen, N. Fischer, K. Haberkorn, S. Wagner, M. Pfeiffer, L. Jin, V. Khon, Y. Wang
(See online at https://doi.org/10.5194/cp-11-305-2015)
