A multiproxy study of Younger Dryas and Early Holocene climatic conditions from the Grabia River paleo-oxbow lake (central Poland)

- We reconstructed temperature and precipitation from the YD paleo-oxbow sediments.
- Early YD climate was continental, precipitation was concentrated in spring and summer.
- Late YD climate was warmer with increasing annual precipitation.
- Spring and summer precipitations determined the river environments in the YD.
- The first reconstruction of water-level depth from the YD paleo-oxbow is presented.

A multi-proxy reconstruction of water depth, temperature and precipitation inferred from Cladocera, Chironomidae and pollen assemblages has been obtained from Świerczyna paleo-oxbow (central Poland) during the Younger Dryas (YD) and Early Holocene. Results suggest that the YD was relatively cold and comprised two main phases. The first (ca. 12,500-12,000 cal. yrs BP) is characterized by a continental climatic regime and a decrease in winter temperatures and precipitation but an increase in spring/summer precipitation. The second phase (ca. 12,000-11,500 cal. yrs BP) was more mild with a variable continental climate, an increase in summer and winter temperature, a lengthening of the growing season and increased annual precipitation. The reconstructed water level generally follows changes in spring and summer precipitation and length of growing season. The frequency and timing of hydroclimatic oscillations at Świerczyna show strong similarities to records from other sites in Europe. This confirms that oxbows and valley mire ecosystems respond to rapid climate change during the YD and Early Holocene. This study therefore brings new insights into the effects of climate changes on river environments, especially during the YD. We also discuss the limitations of water depth, temperature and precipitation reconstructions inferred from the studied biotic assemblages.