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TitleA millennial summer temperature reconstruction for north-eastern Canada using oxygen isotopes in subfossil trees
AuthorNaulier, M; Savard, M M; Bégin, C; Gennaretti, F; Arsenault, D; Marion, J; Nicault, A; Bégin, Y
SourceClimate of the Past vol. 11, issue 9, 2015 p. 1153-1164,
Alt SeriesEarth Sciences Sector, Contribution Series 20140213
PublisherEuropean Geosciences Union
Mediapaper; on-line; digital
File formatpdf
Lat/Long WENS -72.0000 -70.5000 55.0000 54.0000
Subjectsclimate; isotopic studies; oxygen isotopes; fossils; fossil plants; Medieval Climate Anomaly (MCA); Little Ice Age (LIA); climatic reconstructions; tree rings
Illustrationslocation maps; graphs; tables
ProgramCoal & Oil Resources Environmental Sustainability, Environmental Geoscience
AbstractClimatic reconstructions for north-eastern Canada are scarce such that this area is under-represented in global temperature reconstructions. To fill this lack of fundamental knowledge and identify processes influencing climate variability, this study presents the first summer temperature reconstruction for eastern Canada based on a millennial oxygen isotopic series (d18O) from tree rings. For that purpose, we selected 230 well-preserved subfossil stems from the bottom of a boreal lake and five living trees on the lakeshore. The sampling method has permitted to obtain an annually resolved d18O series with a replication of five trees per year. The June to August maximal temperature of the last millennium has been reconstructed using the statistical relationship between the Climatic Research Unit (CRU TS3.1) and d18O data. The resulting millennial series is marked by the well-defined Medieval Warm Anomaly (A.D 1000-1250), the Little Ice Age (A.D 1450-1880) and the modern period (A.D 1950-2010), and an overall cooling trend of -0.6°C/millennium. These climatic trends are in agreement with reconstructions from nearby regions (Arctic, Baffin Bay) and from more remote regions like the Canadian Rockies or Fennoscandia. Our temperature reconstruction clearly indicates that the Medieval Warm Anomaly has been warmer than the modern period, which is relatively cold in the context of the last 1000 years in the studied region. An additional key finding of this research is that the most important cooling events seem to be influenced by solar activities and the coolest period has occurred when a solar minimum was in phase with successive volcanic eruptions. Our study provides a new perspective unravelling key mechanisms that controlled the past climate shifts in north-eastern Canada.
Summary(Plain Language Summary, not published)
Climate reconstructions for northeastern Canada are rare to the point that this region is under-represented in global temperature reconstructions. To address this lack of basic knowledge and identify the processes that influence climate variability, this study presents the first reconstruction of summer temperatures for the north-eastern Canada based on a Millennium oxygen isotope (d18O) series from tree rings. The resulting millennium series is marked by well-defined medieval warm anomaly (AD 1000-1250), the Little Ice Age (1450-1880 AD) and the modern period (AD 1950-2000) periods, with a general trend cooling of -0.6 ° C / millennium. The study provides a new perspective by identifying the key mechanisms that control changes in past climate of the north-eastern Canada.