Abstract. Causes of the Late Glacial to Early Holocene transition phase and
particularly the Younger Dryas period, i.e. the major last cold spell in
central Europe during the Late Glacial, are considered to be keys for
understanding rapid natural climate change in the past. The sediments from
maar lakes in the Eifel, Germany, have turned out to be valuable archives
for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment
core that was retrieved from the Gemündener Maar in the Western Eifel,
Germany. We analysed the hydrogen (δ2H) and oxygen
(δ18O) stable isotope composition of leaf-wax-derived lipid
biomarkers (n-alkanes C27 and C29) and a
hemicellulose-derived sugar biomarker (arabinose), respectively. Both
δ2Hn-alkane and δ18Osugar
are suggested to reflect mainly leaf water of vegetation growing in the
catchment of the Gemündener Maar. Leaf water reflects δ2H
and δ18O of precipitation (primarily temperature-dependent)
modified by evapotranspirative enrichment of leaf water due to transpiration.
Based on the notion that the evapotranspirative enrichment depends primarily
on relative humidity (RH), we apply a previously introduced “coupled
δ2Hn-alkane–δ18Osugar
paleohygrometer approach” to reconstruct the deuterium excess of leaf water
and in turn Late Glacial–Early Holocene RH changes from our Gemündener
Maar record. Our results do not provide evidence for overall markedly dry climatic
conditions having prevailed during the Younger Dryas. Rather, a two-phasing
of the Younger Dryas is supported, with moderate wet conditions at the Allerød
level during the first half and drier conditions during the second half of
the Younger Dryas. Moreover, our results suggest that the amplitude of RH
changes during the Early Holocene was more pronounced than during the Younger
Dryas. This included the occurrence of a “Preboreal Humid Phase”. One
possible explanation for this unexpected finding could be that solar activity
is a hitherto underestimated driver of central European RH changes in the
past.
Late Glacial and Early Holocene Climatic Changes Based on a Multiproxy Lacustrine Sediment Record from Northeast Siberia