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  • 1
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    Online Resource
    The signal of climate changes over the last two millennia in the Gulf of St. Lawrence, eastern Canada
    Cambridge University Press (CUP) ; 2022
    In:  Quaternary Research Vol. 106 ( 2022-03), p. 28-43
    Details
    In: Quaternary Research, Cambridge University Press (CUP), Vol. 106 ( 2022-03), p. 28-43
    Abstract: Climate changes over the past two millennia in the central part of the Gulf of St. Lawrence are documented in this paper with the aim of determining and understanding the natural climate variability and the impact of anthropogenic forcing at a regional scale. The palynological content (dinocysts, pollen, and spores) of the composite marine sediment core MSM46-03 collected in the Laurentian Channel was used to reconstruct oceanographic and climatic changes with a multidecadal temporal resolution. Sea-surface conditions, including summer salinity and temperature, sea-ice cover, and primary productivity, were reconstructed from dinocyst assemblages. Results revealed a remarkable cooling trend of about 4°C after 1230 cal yr BP (720 CE) and a culmination with a cold pulse dated to 170–40 cal yr BP (1780–1910 CE), which likely corresponds to the regional signal of the Little Ice Age. This cold interval was followed by a rapid warming of about 3°C. In the pollen assemblages, the decrease of Pinus abundance over the past 1700 yr suggests changes in wind regimes, likely resulting from increased southerly incursions of cold and dry Arctic air masses into southeastern Canada.
    Type of Medium: Online Resource
    ISSN: 0033-5894 , 1096-0287
    URL: Article
    DOI: 10.1017/qua.2021.56
    RVK:
    RA 1000
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2022
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  • 2
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    Holocene and Last Interglacial cloudiness in eastern Baffin Island, Arctic CanadaThis article is one of a series of papers published in this Special Issue on the theme Polar Climate Stability Network .GEOTOP Publication 2008-0027.
    Canadian Science Publishing ; 2008
    In:  Canadian Journal of Earth Sciences Vol. 45, No. 11 ( 2008-11), p. 1221-1234
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 45, No. 11 ( 2008-11), p. 1221-1234
    Abstract: This study presents Last Interglacial and Holocene vegetation and climate changes at Fog Lake (67°11′N, 63°15′W) on eastern Baffin Island, Arctic Canada. The vegetation cover is reported as vegetation structural types (or biomes). July air temperature and sunshine during the growing season (June–July–August–September) were reconstructed from pollen assemblages using the modern analogue technique. The vegetation of the Last Interglacial period evolved from a prostrate dwarf-shrub tundra to a low- and high-shrub tundra vegetation. The succession of four Arctic biomes was distinguished from the Last Interglacial sediments, whereas only one Arctic biome was recorded in the Holocene sediments. From ca. 8300 cal. years BP to present, hemiprostrate dwarf-shrub tundra occupied the soils around Fog Lake. During the Last Interglacial, growing season sunshine was higher than during the Holocene and July air temperature was 4 to 5 °C warmer than present. A principal component analysis helped in assessing relationship between floristic gradients and climate. The major vegetation changes through the Last Interglacial and Holocene were driven by July air temperature variations, whereas the minor, or subtle, vegetation changes seem rather correlated to September sunshine. This study demonstrates that growing season sunshine conditions can be reconstructed from Arctic pollen assemblages, thus providing information on feedbacks associated with cloud cover and summer temperatures, and therefore growing season length.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/E08-053
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2008
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    detail.hit.zdb_id: 1491201-6
    SSG: 16,13
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  • 3
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    Diachronous evolution of sea surface conditions in the Labrador Sea and Baffin Bay since the last deglaciation
    SAGE Publications ; 2015
    In:  The Holocene Vol. 25, No. 12 ( 2015-12), p. 1882-1897
    Details
    In: The Holocene, SAGE Publications, Vol. 25, No. 12 ( 2015-12), p. 1882-1897
    Abstract: Assessing changes in sea surface conditions due to the effects of past freshwater outflow through Baffin Bay and Davis Strait to the Labrador Sea, hereafter referred to as the Baffin Bay corridor, is relevant in understanding the variability in Labrador Sea Water (LSW) formation. Here, regional changes in oceanographic circulation and sea surface conditions are reconstructed based on organic-walled dinoflagellate cyst (dinocyst) assemblages from four cores collected from deep, central sites of the Baffin Bay corridor. All cores exhibit a major shift in dinocyst assemblages since the late glacial period. This shift consists of a change from a polar–subpolar heterotrophic species assemblage tolerating cold and near permanent ice-covered conditions, to assemblages characterized by a higher diversity and the occurrence of phototrophic taxa associated with mild conditions. Sea surface reconstructions from the modern analogue technique display a shift from harsh, quasi-perennial ice cover to warmer summer sea surface temperatures and a seasonal sea ice. South of the Davis Strait sill, this regime shift occurred at ca. 11.9 cal ka BP due to the influence of North Atlantic waters. Baffin Bay, however, remained densely sea ice covered until about 7.4 cal ka BP, when these warmer waters penetrated into Baffin Bay and mixed with the West Greenland Current (WGC). This mixing was facilitated by the retreat of the Greenland and Laurentide Ice Sheet (LIS) margins. A major change in Labrador Sea surface conditions occurred nearly at about the same time (~7.6 cal ka BP) when the strong stratification of surface waters weakened because of the reduction in meltwater supplies from the LIS that allowed winter convection and the inception of LSW formation. All these new records demonstrate large amplitude fluctuations in sea surface conditions tightly controlled by the relative strengths and shifts of the warmer WGC and colder Baffin Island Current.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/0959683615591352
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
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  • 4
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    Multi-proxy reconstruction of climate changes in the Lower St. Lawrence Estuary, Canada, during the Middle and Late-Holocene
    SAGE Publications ; 2023
    In:  The Holocene
    Details
    In: The Holocene, SAGE Publications
    Abstract: The micropaleontological and palynological content, and geochemical and isotopic composition of a marine sediment core collected off Pointe-des-Monts in eastern Québec, Canada, reveal regional palaeoclimatic and paleoceanographic conditions in the Lower St. Lawrence Estuary over the last ~8200 years. The pollen and spore content allows comparison with the terrestrial palynostratigraphy, whereas dinoflagellate cysts and benthic foraminifera are used to reconstruct sea-surface conditions and bottom water properties, respectively. The dinocyst-based reconstructions indicate shifts between estuarine and oceanic conditions with important changes in sea-surface temperature, salinity, and primary productivity. Both the dinocyst assemblages and the quantitative sea-surface estimates highlight a distinct transition at ca. 4200 cal years BP. It is notably marked by a change towards higher salinity, which suggests reduced freshwater discharge, hence lower precipitation in the watershed, during the Late-Holocene. The isotopic composition (δ 18 O and δ 13 C) and assemblages of the benthic foraminifera indicate centennial to millennial frequency variability of bottom water properties, over a general trend towards decreasing temperatures and increasing ventilation from the beginning of the Middle Holocene until the last century. Since then, reverse trends with abrupt warming and decreasing dissolved oxygen content in bottom water have been observed.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/09596836231185827
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2027956-5
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  • 5
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    Middle to late Wisconsinan climate and ecological changes in northern Alaska: Evidences from the Itkillik River Yedoma
    Elsevier BV ; 2017
    In:  Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 485 ( 2017-11), p. 906-916
    Details
    In: Palaeogeography, Palaeoclimatology, Palaeoecology, Elsevier BV, Vol. 485 ( 2017-11), p. 906-916
    Type of Medium: Online Resource
    ISSN: 0031-0182
    URL: Article
    DOI: 10.1016/j.palaeo.2017.08.006
    RVK:
    TE 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 1497393-5
    detail.hit.zdb_id: 417718-6
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  • 6
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    Dinocyst-based reconstructions of sea ice cover concentration during the Holocene in the Arctic Ocean, the northern North Atlantic Ocean and its adjacent seas
    Elsevier BV ; 2013
    In:  Quaternary Science Reviews Vol. 79 ( 2013-11), p. 111-121
    Details
    In: Quaternary Science Reviews, Elsevier BV, Vol. 79 ( 2013-11), p. 111-121
    Type of Medium: Online Resource
    ISSN: 0277-3791
    URL: Article
    DOI: 10.1016/j.quascirev.2013.07.006
    RVK:
    RA 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2013
    detail.hit.zdb_id: 780249-3
    detail.hit.zdb_id: 1495523-4
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  • 7
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    Histoire postglaciaire de la végétation de la forêt boréale du Québec et du Labrador
    Consortium Erudit ; 2020
    In:  Le Naturaliste canadien Vol. 144, No. 1 ( 2020-03-17), p. 63-76
    Details
    In: Le Naturaliste canadien, Consortium Erudit, Vol. 144, No. 1 ( 2020-03-17), p. 63-76
    Abstract: The postglacial history of the present-day black spruce and balsam fir-dominated bioclimatic domains of boreal Québec and southern Labrador (Canada) was reconstructed using 61 pollen diagrams from lake sediments. The period, deglaciation geography and climate determined whether or not there was an initial tundra vegetation. The establishment of trees and the subsequent development of forest cover were largely a function of climatic changes and the varied occurrence of fire over time. Afforestation was diverse, with numerous vegetational landscapes lacking modern analogues. Their duration was varied, with certain species showing extreme cases of cornering and effusion, both in space and time. The establishment of forests similar to those found today was gradual. As the climate warmed, there was an increase in the abundance of relatively thermophilous species. This progression culminated between 8,000 and 4,000 years ago. Climatic deterioration then caused a regression of the vegetation cover, giving rise to the present bioclimatic domains.
    Type of Medium: Online Resource
    ISSN: 1929-3208 , 0028-0798
    URL: Article
    DOI: 10.7202/1070086ar
    Language: French
    Publisher: Consortium Erudit
    Publication Date: 2020
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    detail.hit.zdb_id: 2658776-2
    detail.hit.zdb_id: 207093-5
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  • 8
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    Le till pollinifère de la péninsule du Nunavik, Québec septentrionnal
    Consortium Erudit ; 2007
    In:  Géographie physique et Quaternaire Vol. 50, No. 3 ( 2007-11-30), p. 331-340
    Details
    In: Géographie physique et Quaternaire, Consortium Erudit, Vol. 50, No. 3 ( 2007-11-30), p. 331-340
    Abstract: Erstaunlich hohe Pollen-Konzentrationen wurdem im Till in der Nâhe des Kraters von Nouveau-Québec festgestellt (Richard et al., 1991; Frechette 1994). Wir haben die Hypothèse aufgestellt, daB das nahe bei der glazialen Eisscheide gelegene Till reicher an Pollen ist, als die von ihr entfemten Tills. Die Hypothèse wird in diesem Beitrag ûberprùft. In der Tat enthâlt das Till aus dem Zentrum von Nunavik nahe bei der glazialen Eisscheide Pollen-Konzentrationen der GrôBenordung -31 000 Korner/g, wogegen die mehr Ôstlich und westlich gelegenen mittlere Werte von -8500 Kôrner/ g bzw. -6800 Korner/g haben. Die Sedimente aus dem Zentrum von Nunavik konnten vor einer intensiven glazialen Erosion bewahrt werden, so daB der wâhrend der vorher-gehenden lnterstadiale und Interglaziale angesammelte Pollen erhalten und wieder-verwendet werden konnte. Auf den ersten Blick entsprechen die Pollen-Spektren vom Till der Halbinsel Nunavik ungefàhr der heutigen Biogeographie. Die Pollen-Einheiten vom mehr nôrdlichen Till scheinen eine Pflanzen-Tundra zu spiegeln, wogegen diejenigen vom sudlicheren Till eher einer Busch-Tundra gleichen. Die Analyse der Hauptbestandteile erlaubte die Polleneinheiten des Tills mit denen der Oberflàchensedimente der umliegenden Seen zu vergleichen. Die Ergebnisse heben das Fehlen gegenwàrtiger Entsprechungen hervor und lassen auch Unterschiede in der Verteilung oder Ausbreitung der bioklimatischen Zonen im Vor-Wisconsinium erkennen.
    Type of Medium: Online Resource
    ISSN: 1492-143X , 0705-7199
    URL: Article
    DOI: 10.7202/033103ar
    Language: French
    Publisher: Consortium Erudit
    Publication Date: 2007
    detail.hit.zdb_id: 2035245-1
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  • 9
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    Resilience of the boreal forest in response to Holocene fire-frequency changes assessed by pollen diversity and population dynamics
    CSIRO Publishing ; 2010
    In:  International Journal of Wildland Fire Vol. 19, No. 8 ( 2010), p. 1026-
    Details
    In: International Journal of Wildland Fire, CSIRO Publishing, Vol. 19, No. 8 ( 2010), p. 1026-
    Abstract: The hypothesis that changes in fire frequency control the long-term dynamics of boreal forests is tested on the basis of paleodata. Sites with different wildfire histories at the regional scale should exhibit different vegetation trajectories. Mean fire intervals and vegetation reconstructions are based respectively on sedimentary charcoal and pollen from two small lakes, one in the Mixedwood boreal forests and the second in the Coniferous boreal forests. The pollen-inferred vegetation exhibits different trajectories of boreal forest dynamics after afforestation, whereas mean fire intervals have no significant or a delayed impact on the pollen data, either in terms of diversity or trajectories. These boreal forests appear resilient to changes in fire regimes, although subtle modifications can be highlighted. Vegetation compositions have converged during the last 1200 years with the decrease in mean fire intervals, owing to an increasing abundance of boreal species at the southern site (Mixedwood), whereas changes are less pronounced at the northern site (Coniferous). Although wildfire is a natural property of boreal ecosystems, this study does not support the hypothesis that changes in mean fire intervals are the key process controlling long-term vegetation transformation. Fluctuations in mean fire intervals alone do not explain the historical and current distribution of vegetation, but they may have accelerated the climatic process of borealisation, likely resulting from orbital forcing.
    Type of Medium: Online Resource
    ISSN: 1049-8001
    URL: Article
    DOI: 10.1071/WF09097
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2010
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  • 10
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    Holocene climate history of the Nunatsiavut (northern Labrador, Canada) established from pollen and dinoflagellate cyst assemblages covering the past 7000 years
    SAGE Publications ; 2016
    In:  The Holocene Vol. 26, No. 1 ( 2016-01), p. 44-60
    Details
    In: The Holocene, SAGE Publications, Vol. 26, No. 1 ( 2016-01), p. 44-60
    Abstract: This study documents the past ~7000 years of Holocene climatic history for Labrador and Nunatsiavut, using a sedimentary sequence of more than 8 m retrieved in Nachvak fjord, one of the northernmost fjords of Nunatsiavut. Using a multi-proxy approach combining a solid Accelerator Mass Spectrometry (AMS)- 14 C chronology and the fossil assemblages of pollen grains and dinoflagellate cysts (dinocysts), we were able to compare terrestrial and marine records in an effort to obtain a better understanding of the mid- to late-Holocene climate history of the Nunatsiavut. Records begin at the end of the deglaciation and showed a general delay in the sequence of climate events which followed, both in terrestrial and marine realms. The presence of Pentapharsodinium dalei in great abundance in Nachvak Fjord revealed a strong influence of the North Atlantic Ocean and the Labrador Sea until ~3000 yr BP. Afterward, its rather fast disappearance marked the increased influence of Arctic waters. The last 1000 years show climate stability in the region over the marine realm and a cooling trend over terrestrial landscapes.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/0959683615596823
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
    detail.hit.zdb_id: 2027956-5
    SSG: 14
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