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TitreLake mud: a tool to identify global teleconnections and quantify the range of environmental responses to climate variability in the Northwest Territories, Canada
AuteurMacumber, A L; Patterson, R T; Galloway, J M; Falck, H; Swindles, G T; Crann, C
SourceNorthwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2013, 2013 p. 41
Année2013
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130445
Réunion41st Annual Yellowknife Geoscience Forum; Yellowknife; CA; Novembre 19-21, 2013
Documentpublication en série
Lang.anglais
Mediapapier
Formatspdf
ProvinceTerritoires du Nord-Ouest
Sujetsfluctuations climatiques; climat arctique; effets climatiques; effets sur l'environnement; etudes de l'environnement; paléoenvironnement; paléoclimats; Changement climatique; géologie de l'environnement; géologie des dépôts meubles/géomorphologie
Programmeadaptation et impacts sur l'environnement, environnement du nord, Géosciences de l'environnement
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
Recent climate changes affecting the Canadian Subarctic have prompted policy planners to seek a better understanding of regional climate variability and the range of associated environmental responses. A key concern is the viability of current infrastructure and the necessity to invest in more permanent overland routes. The dearth of consistent long-term records of regional climate has greatly hindered and even precludes the accurate modeling of future climate in the region. Previous studies have tracked coarse temporal scale changes in treeline movement but not at the temporal resolution necessary to identify the oscillatory nature of global teleconnections which contribute to regional climate variability. Also missing is the range of associated environmental responses to historical climate variability. Only when this response is understood can future scenarios of climate models be put into terms of environmental impact.

Global teleconnections, such as the El Niño/Southern Oscillation, are the result of large scale oceanic and atmospheric circulatory processes. They temporally fluctuate at specific frequencies and thus environmental processes they affect, whether directly or indirectly, will record a similar fluctuation within their paleorecords. The particle size distribution of lake sediments represents variability in the energy within the surrounding catchment of the lake. This energy can be modulated by sediment availability, changes in snowpack, presence or absence of vegetation, and average precipitation. These all in turn are modulated by regional climate variability which is the result of the forcing behaviour of global teleconnections. Sediment freeze cores were collected from two boreal subarctic lakes ¿ Waite Lake and Danny¿s Lake ¿ in the Northwest Territories, Canada and were subsampled at millimeter intervals utilizing a custom-designed freeze core microtome. Time series analysis of the grain size distributions identified periodicities equivalent to those seen in records of the El Niño/Southern Oscillation, the Pacific Decadal Oscillation and the Gleissberg Cycle. These results help to clarify which teleconnections are associated with the regional climate variability of the canadian Subarctic.

Biotic proxies are an important tool for tracking historical environmental changes due to climatic variability. Arcellacea are a freshwater protist, which undergo rapid generation times, are resistant to dissolution and are numerous in lake sediments. A suite of geochemical and sedimentological analysis of fifty six lakes spanning North from Yellowknife into the southern arctic ecozone of the Northwest Territories were used to characterize lakes and the arcellacean populations they contain. This information coupled with downcore studies of ancient arcellacean populations can be used to reconstruct an environmental history for the region. These results help to identify important climate events, possible analogue scenarios and define the range of expected environmental response to natural climatic variability.

Altogether these results will provide policy makers and climate modelers with the required information to project possible future climate scenarios and to assess the viability of present and future infrastructure in the Canadian Subarctic.
Résumé(Résumé en langage clair et simple, non publié)
En raison des changements climatiques survenus récemment dans la zone subarctique du Canada, les gestionnaires de l'utilisation des terres ont besoin de mieux comprendre la variabilité climatique et ses répercussions sur l'environnement. La viabilité de l'infrastructure est un sujet de préoccupation. Les routes de transport terrestres sont essentielles au maintien de la prospérité de l'économie tributaire des ressources minérales du nord du Canada. Nous utilisons des analyses à haute résolution des signatures biotiques, physiques et chimiques préservées dans les sédiments lacustres du centre des Territoires du Nord-Ouest pour examiner les répercussions des téléconnexions planétaires sur le climat du centre des T.N.-O. Nous observons, en utilisant une analyse des séries chronologiques, des périodicités équivalant au phénomène El Niño-oscillation australe, à l'Oscillation décennale du Pacifique et au cycle solaire de Gleissberg. Ces résultats sont utiles pour la détermination des mécanismes de forçage du climat dans le nord du Canada.
GEOSCAN ID293588