Ultra-high resolution pollen record from the northern Andes reveals rapid shifts in montane climates within the last two glacial cycles
journal contributionposted on 24.10.2012, 09:06 by M.H.M. Groot, R.G. Bogotá, L.J. Lourens, H. Hooghiemstra, M. Vriend, Juan C. Berrio, E. Tuenter, J. Van Der Plicht, B. Van Geel, M. Ziegler, S.L. Weber, A. Betancourt, L. Contreras, S. Gaviria, C. Giraldo, N. González, J.H.F. Jansen, M. Konert, D. Ortega, O. Rangel, G. Sarmiento, J. Vandenberghe, T. Van Der Hammen, M. Van Der Linden, W. Westerhoff
Here we developed a composite pollen-based record of altitudinal vegetation changes from Lake Fúquene (5° N) in Colombia at 2540 m elevation. We quantitatively calibrated Arboreal Pollen percentages (AP%) into mean annual temperature (MAT) changes with an unprecedented ~60-year resolution over the past 284 000 years. An age model for the AP% record was constructed using frequency analysis in the depth domain and tuning of the distinct obliquity-related variations to the latest marine oxygen isotope stacked record. The reconstructed MAT record largely concurs with the ~100 and 41-kyr (obliquity) paced glacial cycles and is superimposed by extreme changes of up to 7 to 10° Celsius within a few hundred years at the major glacial terminations and during marine isotope stage 3, suggesting an unprecedented North Atlantic – equatorial link. Using intermediate complexity transient climate modelling experiments, we demonstrate that ice volume and greenhouse gasses are the major forcing agents causing the orbital-related MAT changes, while direct precession-induced insolation changes had no significant impact on the high mountain vegetation during the last two glacial cycles.