A high-resolution oxygen isotope reconstruction of humidity changes in central Sweden during the late Holocene

Records of stable oxygen isotope variations from a variety of proxies have been used in palaeoclimatic research since the 1950’s. Several studies have applied stable isotope analysis of lake sediments to reconstruct past climate changes in central and northern Sweden, including a study of Lake Blektjärnen in Jämtland, central Sweden, by Andersson (2010). In this study, sediments from that same lake were sampled for stable isotope analysis of bulk carbonates with the aim to improve the resolution of the isotopic record for the last two millennia. The results indicate a shift from relatively drier to wetter conditions between ~2,300–1,300 cal. years BP, generally wet conditions close to the Medieval Warm Period (~1,000–750 cal. years BP) and generally dry conditions during the Little Ice Age (~550–150 cal. years BP). These results are in agreement with previous palaeoclimatic reconstructions in the region. The isotopic record of Lake Blektjärnen was completed for the last ~2,350 years at a resolution of ~15 years per sample, three times higher than that of the previous study, displaying the advantages of bulk carbonate sampling for stable isotope analysis and providing a high-resolution dataset on humidity changes in central Sweden during the late Holocene