A new 1500-year-long varve thickness record from Labrador, Canada, uncovers significant insights into large-scale climate variability in the Atlantic

Abstract

Grand Lake, located in Labrador, at the northeastern margin of North America, is a deep lacustrine basin that contains a well-preserved annual laminations record spanning the interval 493 to 2016 CE (1524 years). The chronology of this new varved sequence is established from layer counting of high-resolution images of thin sections. Radiometric dating (137Cs and 14C) validates the reliability of the varve chronology. Varve thickness is significantly correlated (r = 0.38) with the total precipitation recorded at the nearest weather station Goose A. The varve thickness series reveals high values during the 1050-1225 CE period, which corresponds to the Medieval Climate Anomaly, whereas the 15th-19th centuries, related to the Little Ice Age, shows low values. The teleconnections between several Goose A instrumental data series and some modes of climate variability such as the winter Greenland Blocking (negative North-Atlantic Oscillation) and the significant correlations between our varve thickness record and three other Northern Hemisphere high-resolution proxy records suggest that the Grand Lake record tracks North-Western Atlantic large-scale modes of hydroclimate variability over the past ∼ 1500 years.