Mandagskollokvium - How unique is the Holocene?

Norbert Kuehl:

How unique is the Holocene? Quantitative climate reconstructions of four warm periods in north central Europe.

ABSTRACT
Comparison of past interglacials with our present interglacial is key to better understand present and future climate. For example, Marine Isotope Stadium (MIS) 11 has been considered an analogue for Holocene and future natural climate changes because of similarity in insolation between the two periods.
Pollen from lake sediments potentially record the complete vegetational succession within interglacials in high resolution. Vegetation strongly depends on climate, hence botanical fossils belong to the often used proxy data for reconstructing terrestrial palaeo climate. The method that was used for climate reconstructions is a probabilistic, multivariate method based on probability density functions (pdf-method). The method is robust to local site characteristics and includes an explicit error estimation.
Quantitative climate reconstructions of sites representing four interglacials from (north) central Europe from last ~400.000 years will be shown, including the terrestrial equivalent of MIS 11. The sites are with varved sediments, providing excellent time control for each of the interglacials, and high pollen counts provide the sound basis for the climate reconstructions. Vegetation successions in interglacials are in principle similar, but this does not necessarily mean that the climatic evolution was identical. The climate reconstructions show that the climatic history of each interglacial is unique when considering the combination of e.g. reconstructed values, duration, beginning and trend within the interglacial. Hence, none of these interglacials can be taken as close analogue of any other interglacial. The global situation accounts for some of these features, but the situation on a more regional scale must also be taken into consideration.