NOAA/WDS Paleoclimatology - Faroe Islands 125,000 Year Lake Sediment Leaf Wax Stable Isotope Data

The Last Interglacial period (LIG) is Earth's most recent globally warm period and is analogous in some ways to projected future global warming. However, questions remain regarding the state of the climate during the LIG in the North Atlantic, a region that is extremely sensitive to changes in oceanic and atmospheric circulation. Here, we present hydrogen and carbon isotope (dD and d13C) records from a suite of plant wax biomarkers preserved in Holocene and LIG lacustrine sediments from the North Atlantic Faroe Islands and interpret them as qualitative proxies for temperature and hydroclimate variability. These data are used to directly compare LIG and Holocene climate using the same proxy approaches from the same terrestrial location. Measuring multiple isotopes on multiple types of waxes elucidates the sources of homologous plant waxes. We deduce that the dD values of long-chain n-alkanes (C27-C33) and mid-chain n-alkanes (C23-C25) in these sedimentary archives reflect leaf water and lake water dD values, respectively, while the dD values for both long-chain (C28-C30) and mid-chain n-alkanoic acids (C24-C26) primarily represent lake water dD values. Plant wax-inferred dD values of precipitation during the early Holocene (10,100 to 8,200 cal yr BP) are ~35 per mil more positive than late Holocene values, and decline over the Holocene. dD-inferred hydrologic change and d13C -inferred plant water use efficiency both indicate that the Faroe Islands became drier throughout the Holocene. Comparison with measurements from LIG plant waxes indicates that late LIG in the Faroe Islands was hydrologically similar to the early-to mid-Holocene (8,200 to 4,000 cal yr BP), with enriched precipitation isotopes and reduced evapotranspiration indicating a warmer, wetter environment.