Delayed hydrological response to Greenland cooling at the onset of the Younger Dryas in western Europe

• Published in: Nature geoscience Vol. 7; no. 2; pp. 109 - 112
• Main Authors: Rach, O., Brauer, A., Wilkes, H., Sachse, D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2014; Nature Publishing Group
• Subjects: 140/58; 704/106/413; Deglaciation; Earth Sciences; Earth System Sciences; Environmental changes; Geochemistry; Geology; Geophysics/Geodesy; Hydroclimate; Hydrogen; Lake sediments; letter; Lipids; Sea ice; AN, North Atlantic; Germany, Eifel, Meerfelder Maar; ANE, Europe; AN, Greenland
• ISSN: 1752-0894; 1752-0908
• DOI: 10.1038/ngeo2053

During the Younger Dryas cold event about 12,800 years ago, environmental change in western Europe seems to occur 170 years after cooling over Greenland. Lake sediment analyses confirm this delay, and suggest European hydrological and vegetation change occurred only after the build-up of sea ice in the North Atlantic pushed the westerly wind system south. The general warming trend of the last deglaciation was interrupted by the Younger Dryas, a period of abrupt cooling and widespread environmental change 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . Ice core records suggest the abrupt cooling began 12,846 years ago in Greenland 10 , about 170 years before the significant environmental and vegetation change in western Europe 7 classically defined as the Younger Dryas. However, this difference in timing falls within age model uncertainties. Here we use the hydrogen isotope composition of lipid biomarkers from precisely dated varved sediments from Lake Meerfelder Maar to reconstruct hydroclimate over western Europe. We observe a decrease in the hydrogen isotope values of both aquatic and terrestrial lipids 12,850 years ago, indicating cooling climate in this region synchronous with the abrupt cooling in Greenland. A second drop occurs 170 years later, mainly in the hydrogen isotope record of aquatic lipids but to a lesser extent in the terrestrial lipids, which we attribute to aridification, as well as a change in moisture source and pathway. We thus confirm that there was indeed a lag between cooling and substantial hydrologic and environmental change in western Europe. We suggest the delay is related to the expansion of sea ice in the North Atlantic Ocean and the subsequent southward migration of the westerly wind system 9 . We further suggest that these hydrological changes amplified environmental change in western Europe at the onset of the Younger Dryas.