|Title||The Holocene climate optimum as archived by lacustrine sedimentary records from the central Northwest Territories, Canada|
|Author||Macumber, A L; Patterson, R T; Galloway, J M; Vermaire, J C; Falck, H; Clark, I|
|Source||The International Union for Quaternary Science (INQUA), abstracts; 2015 p. 1-2|
|Links||Online - En ligne|
|Alt Series||Earth Sciences Sector, Contribution Series 20150075|
|Meeting||The XIX International Union for Quaternary Science (INQUA) Congress; Nagoya; JP; July 26 - August 2, 2015|
|Media||paper; on-line; digital|
|Lat/Long WENS||-107.0000 -106.5000 60.5000 60.2500|
|Subjects||surficial geology/geomorphology; Holocene; climate; climate, arctic; climatic fluctuations; glacial erosion; lacustrine environments; lacustrine deposits; Cenozoic|
|Program||Tools for environmental impacts and adaptation for metal mining, Environmental Geoscience|
|Abstract||The central Northwest Territories of Canada is a vast region known to be sensitive to Holocene climate variability. Glacial erosion has resulted in a landscape characterized by abundant lakes that
archive continuous sedimentary records of Holocene climate variability. One key feature of the region is the taiga-tundra treeline, which during the Holocene climate optimum (HCO) was situated over 100 km to the north of the present day
Carleton Lake is located 120 km north of treeline. Age-depth modelling of a frozen sediment core gave a basal date of 7500 cal yr BP. Between 6 to 3.8 kyr BP there was a sharp increase in both total organic carbon and the C/N ratio.
Constrained incremental sums of squares cluster analysis of grain size parameters, stable isotopes and Arcellacea (testate lobose amoebae) provided confirmation that the warm period ended at this site ~3750 cal yr BP.
Arcellacea are benthic
heterotrophs that are sensitive to limnological change. Principal component analysis (PCA) of the assemblage data revealed two PCA axes that show significant changes during this period. The second PCA axis showed an increase during the initial phase
of the HCO. The third PCA axis showed increases before and after the warm phase. A similar pattern is seen in both axes subsequent to the termination of the Little Ice Age. Studying the impact of Holocene climate variability on Arcellacea during the
HCO has importance for understanding the impact of climate warming in the region.
A core from Danny’s Lake located south of treeline archives evidence of the 8.2 kyr cooling event that follows the drainage of Lake Agassiz into Hudson Bay. This is
evidenced by an increase in a coarse silt component that we interpret as increased catchment runoff due to a decrease of vegetation cover brought on by a deteriorating climate.
|Summary||(Plain Language Summary, not published)|
We use a multi-proxy paleolimnoogical approach to reconstruct the climate of the central Northwest Territories to provide insight on the response of
ecosystems to current and predicted climate change. A sediment core from Carleton Lake, located 120 km north of modern treeline, documents a ~7500 cal. year climate history. Multivariate statistical analyses of arcellacea, testate lobose amoebae,
preserved in the sediments of this lake reveal the termination of the Holocene Climate Optimum at ~3750 cal yr BP.