Hässeldala – a key site for Last Termination climate events in northern Europe

Abstract

The Last Termination (19 000-11 000 a BP) with its rapid and distinct climate shifts provides a perfect laboratory to study the nature and regional impact of climate variability. The sedimentary succession from the ancient lake at Hässeldala Port in southern Sweden with its distinct Lateglacial/early Holocene stratigraphy (>14.1-9.5 cal. ka BP) is one of the few chronologically well- constrained, multi-proxy sites in Europe that capture a variety of local and regional climatic and environmental signals. Here we present Hässeldala’s multi- proxy records (lithology, geochemistry, pollen, diatoms, chironomids, biomarkers, hydrogen isotopes) in a refined age model and place the observed changes in lake status, catchment vegetation, summer temperatures and hydroclimate in a wider regional context. Reconstructed mean July temperatures increased between ~14.1 and ~13.1 cal. ka BP and subsequently declined. This latter cooling coincided with drier hydroclimatic conditions that were likely associated with a freshening of the Nordic Seas and started a few hundred years before the onset of Greenland Stadial 1 (~12.9 cal. ka BP). Our proxies suggest a further shift towards colder and drier conditions as late as ~12.7 cal. ka BP, which was followed by the establishment of a stadial climate regime (~12.5-11.8 cal. ka BP). The onset of warmer and wetter conditions led the Holocene warming over Greenland by ~200 years. Hässeldala’s proxies thus highlight the complexity of environmental and hydrological responses across abrupt climate transitions in northern Europe.