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TitlePalynological analysis of Danny's Lake, central Northwest Territories
AuthorSulphur, K C; Galloway, J M; Hills, L V; Crann, C; Macumber, A; Patterson, R T; Falck, H
Source40th Annual Yellowknife Geoscience Forum Abstracts of Talks and Posters ; by Watson, D M (ed.); Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2012, 2012 p. 70-71
Alt SeriesEarth Sciences Sector, Contribution Series 20130115
Meeting 40th annual Yellowknife Geoscience Forum; Yellowknife; CA; November 13-15, 2012
File formatdoc; pdf
ProvinceNorthwest Territories
AreaDanny's Lake
Lat/Long WENS-110.2500 -110.0000 64.5000 64.2500
Subjectspaleontology; environmental geology; ice; ice thicknesses; vegetation; climatic fluctuations; climate; climate, arctic
Programenvironmental impacts and adaptation in the northern environment, Environmental Geoscience
LinksOnline - En Ligne
AbstractThe Tibbitt to Contwoyto Winter Road (TCWR) is the critical link in the supply chain to northern diamond mines, including the Diavik Diamond Mine (Rio Tinto Group) and Ekati Diamond Mine (NHP Billiton Inc.). Use of the TCWR is limited to only a few months of the year because the road is built over frozen lakes; cold winter temperatures are required to maintain sufficient ice thickness. Northwest Canada has experienced some of the most rapid warming (on the order of 1.5 to 2° C per decade) in the Northern Hemisphere during the last few decades and climate models predict continued temperature increases for at least the next century. Recent climate fluctuations have resulted in a reduction of ice cover duration and thickness along the route of the TCWR, which has substantial economic impact for northern industries. Understanding cyclic climate phenomena in the Northwest Territories will enhance our ability to predict future climate and the impact on the TCWR. However, instrumental climate records extend only to the 1940's in the Northwest Territories. To place recent climate change in a geologic perspective, proxy records must be used. Palynology, the study of pollen and spores, is one of the best means for reconstructing past climate.

Danny's Lake (63º 28' 32'' N; 112º 32' 47'' W) is the first lake to the north of the 49th land portage along the TCWR and is approximately 17 km south of Lac de Gras and the Diavik Diamond Mine. It is located near the important ecotone boundary of the transition from boreal forest to tundra and is thus situated in a sensitive recording area where past climate change can be determined. A 111-cm sediment core was taken from Danny's Lake in March, 2010. These lake sediments contain well-preserved pollen and spores and microscopic charcoal. Pollen and spores will be used to reconstruct how vegetation communities in the central Northwest Territories have changed over the past ~3500 years. These changes in plant communities have ecological implications that can be related to climate variations. In this way, a palynological study can be used as a proxy of climate, and thus document past climate cycles. These past climate cycles can then be used to predict future climate cycles, and therefore aid in predicting the future viability. Microscopic charcoal will also be analyzed in sediment core samples from Danny's Lake to investigate fire regimes in the study region, how fire regimes have been affected by climate change, and how vegetation communities have responded to fire disturbance. Understanding disturbance regimes, and community response to fire disturbance, is important because occurrences of fires are affected by weather variations, and long-term trends in climate. Lightning strikes are major sources of tundra fires. The variations in weather and length of the storm season are affected by long-term climatic changes. This palynological study will help reconstruct the climate history of the area, and aid in predicting future climate cycles that will affect the TCWR, and thus the natural resource development in the north.
Summary(Plain Language Summary, not published)
Pollen analysis of lake sediments retrieved from Danny's Lake in the central NWT show that this regione experienced considerable climate change over the past ~8500 years. Fires were common in shrub tundra environments in the early Holocene when climate was warm and dry. Neoglacial cooling resulted in northward movement of the treeline and a reduction in the intensity and frequency of forest fires. The pollen record captures pan-hemispherical climate events such as the Medieval Warm Period and Little Ice Age. Both of these events may be used as analogues of environmental response to future climate change.