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| Titel |
A millennial summer temperature reconstruction for northeastern Canada using oxygen isotopes in subfossil trees |
| VerfasserIn |
M. Naulier, M. M. Savard, C. Bégin, F. Gennaretti, D. Arseneault, J. Marion, A. Nicault, Y. Bégin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 9 ; Nr. 11, no. 9 (2015-09-17), S.1153-1164 |
| Datensatznummer |
250117402
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| Publikation (Nr.) |
 copernicus.org/cp-11-1153-2015.pdf |
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| Zusammenfassung |
| Climatic reconstructions for northeastern Canada are scarce such that this
area is under-represented in global temperature reconstructions. To fill
this lack of knowledge and identify the most important processes influencing
climate variability, this study presents the first summer temperature
reconstruction for eastern Canada based on a millennial oxygen isotopic
series (δ18O) from tree rings. For this 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 permitted an annually
resolved δ18O 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 relation between Climatic Research Unit
(CRU TS3.1) and δ18O data. The resulting millennial series is
marked by the well-defined Medieval Climate Anomaly (MCA; AD 1000–1250), the
Little Ice Age (AD 1450–1880) and the modern period (AD 1950–2010), and an
overall average cooling trend of −0.6 °C millennium−1. These
climatic periods and climatic low-frequency trends are in agreement with the
only reconstruction available for northeastern Canada and others from nearby
regions (Arctic, Baffin Bay) as well as some remote regions like the
Canadian Rockies or Fennoscandia. Our temperature reconstruction indicates
that the Medieval Climate Anomaly was characterized by a temperature range
similar to the one of the modern period in the study region. However, the
temperature increase during the last 3 decades is one of the fastest
warming observed over the last millennium (+1.9 °C between
1970–2000). An additional key finding of this research is that the coldest
episodes mainly coincide with low solar activities and the extremely cold
period of the early 19th century has occurred when a solar minimum was
in phase with successive intense volcanic eruptions. Our study provides a
new perspective unraveling key mechanisms that controlled the past climate
shifts in northeastern Canada. |
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