Klimaatvariabiliteit op extreem nauwkeurige tijdschaal van het Eemien in de tropen (Colombia); een zoektocht naar drijvende krachten en werkingsmechanismen
03 / 2003 - 02 / 2007
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
This project aims to generate a pollen-based record of climate variability from Lake Fuquene (4°N) of the last interglacial period (Eemian = Marine Isotope Stage 5e) with extreme temporal resolution (20 yr over a period of 17,000 yr > 850 data points). Additional proxies (a.o. grain size analysis, LOI) will be analysed. The well-known problem of obtaining chronological control for the sediments of this period (c. 113,000-130,000 yr ago) will be based on precise correlation with pollen record Funza-2A, U-Th dating, and TL-dating of expected intercalated sands. We compare the available record of Holocene climate variability, climate trends, and evolution of floral diversity with that of the Eemian period, being the nearest period in the geological history that offers comparable climate conditions with today. We will collect two parallel cores from the centre of the lake from a floating pontoon to avoid small gaps in the record at core barrel breaks. New technical methods, such as analysis of a selection of pollen taxa based on ecological range studies, multivariate data analysis, and the innovative technique of downcore biomisation of pollen data will be used to break through in current standards. Holocene climate variability seems relatively constant with low amplitude but, based on our pilot study, Eemian climate variability in our study area seems significant with 1200-2500 yr periodicities superimposed on sub-Milankovitch climatic cycles (Mommersteeg 1998). Possible driving forces of climate change will be explored on the basis of comparisons with records from Greenland and deep-ocean 18O records, and inverse modelling. Results will serve the international Eemian project and raw data are delivered to the Latin American Pollen Database after publication.