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An 11,000-year record of driftwood delivery to the western Queen Elizabeth Islands, Arctic Canada
Abstract
Fifty-six new radiocarbon dates from driftwood (mainly Larix, Picea and Populus spp.) collected from the modern and raised shorelines of Melville and Eglinton islands (western Canadian High Arctic) are presented and compared to other driftwood collections from the Canadian Arctic Archipelago (CAA) and Greenland. By documenting the species (provenance) and spatio-temporal distribution of driftwood at various sites across the Arctic, regional characterizations of former sea-ice conditions and changes in Arctic Ocean circulation patterns may be deduced. The earliest postglacial invasion of the Canadian Arctic Archipelago by driftwood is recorded on central Melville Island at c. 11 cal. ka BP, suggesting that the modern circulation pattern of Arctic Ocean surface water southeast through the archipelago was established >1000 years earlier than previously proposed. Throughout most of the Holocene until c. 1.0 cal. ka BP, the rate of driftwood delivery to the western Arctic islands was low (~1 recorded stranding event per 200 years) and intermittent, with the longest break in the record occurring between c. 3.0 and 5.0 cal. ka BP. This 2000-year hiatus is attributed to a period of colder temperatures causing severe sea-ice conditions and effectively making the coasts of the western Arctic islands inaccessible. After c. 1.0 cal. ka BP, driftwood incursion increased to maximum Holocene levels (~1 recorded stranding event every 20 years). Driftwood identified to the genus level as Larix that was delivered at this time suggests that the Trans Polar Drift current was regularly in its most southwestern position, related to a dominantly positive Arctic Oscillation mode. The Little Ice Age appears to have had little impact on driftwood entry to the western Canadian Arctic Archipelago, indeed the general abundance in the latest Holocene may record infrequent landfast sea ice.
... Arctic driftwood-based sea ice reconstructions to date have been predominantly based on data from specific regions [e.g., Dyke et al., 1997;Funder et al., 2011;Nixon et al., 2016]. In order to infer the role of atmospheric and oceanic circulation in controlling the patterns of sea ice conditions and dynamics-and consequently driftwood deposition, a pan-Arctic perspective of driftwood fluctuations is important, as local trends are influenced by local conditions, coastal geomorphology, and smaller scale coastal currents. ...
... Previous studies exploring driftwood as a proxy for sea ice have used a genus-based division of driftwood to indicate wood provenance, with Larix and Picea signifying the Siberian and North American boreal forests, respectively [e.g., H€ aggblom, 1982;Eggertsson, 1993;Dyke et al., 1997;Funder et al., 2011;Hellmann et al., 2013b;Nixon et al., 2016]. Although this broad demarcation has shown to be a useful tool, the complexity of the species distribution [e.g., Hellmann et al., 2016], and the presence of Larix and Picea in both continents suggest that a refinement in such methods could be achieved through increasing the taxonomic precision of driftwood identification. ...
... Data from 913 driftwood samples previously collected throughout the western Arctic coastline and covering the Holocene was collated from a range of previous studies [Allard and Tremblay, 1983;Atkinson and England, 2004;Bednarski, 1984;Bennike, 2004;Bennike and Weidick, 2001;Birkenmajer and Olsson, 1970;Blake, 1961aBlake, , 1961bBlake, , 1970Blake, , 1989Blake, , 1972Blake, , 1974Blake, , 1975Blake, , 1983Blake, , 1986Blake, , 1987Blake, , 1993Bondevik et al., 1995;Broecker and Olson, 1959;Crary, 1960;Dibner, 1965;Dyke, 1979Dyke, , 1984Dyke, , 1993Dyke, , 1998Dyke and Morris, 1990;Dyke and Savelle, 2000, 2003, 2009Dyke et al., 1989Dyke et al., , 1991Dyke et al., , 1996Dyke et al., , 2011England, 1976aEngland, , 1976bEngland, , 1978England, , 1983England, , 1985England, , 1990England et al., 1978England et al., , 2017Evans, 1988Evans, , 1990Evans and England, 1992;Forman, 1990;Forman and Ingolfsson, 2000;Forman et al., 1996Forman et al., , 1997Forman et al., , 1999aForman et al., , 1999bFunder et al., 2011;Glazovskiy et al., 1992;Grosswald, 1963;Grosswald et al., 1973;H€ aggblom, 1982;Hattersley-Smith et al., 1969;Henoch, 1964;Hillaire-Marcel, 1976;Hjort, 1997;Hodgson, 1992;Hodgson et al., 1991;Hoppe et al., 1969;Ives et al., 1964;Johansen, 1998;Knuth, 1967;Kovaleva, 1974;Landvik and Salvigsen, 1987;Landvik et al., 2001;Lemmen, 1988;Lowdon and Blake, 1973, 1979Lubinski, 1998;Lubinski et al., 1999;Marthinussen, 1962;McLaren and Barnett, 1978;McNeely, 2005McNeely, , 2006McNeely and McCuaig, 1991;Mielke and Long, 1969;Naslund et al., 1994;Nixon et al., 2014Nixon et al., , 2016Nydal, 1960;O Cofaigh, 1999;Olson and Broecker, 1959;Preston et al., 1955;Salvigsen and Osterholm, 1982;Salvigsen, 1978Salvigsen, , 1984Salvigsen and Mangerud, 1991;Salvigsen and Nydal, 1981;Schledermann, 1978;Sharpe, 1992;Stewart and England, 1983;St-Hillaire-Gravel et al., 2015;Taylor, 1975;Trautman, 1963;Wagner et al., 2010;Washburn, 1962;Webber et al., 1970;Weidick, 1972Weidick, , 1975Weidick, , 1977Weihe, 1996;Zale and Brydsten, 1993;Zeeberg et al., 2001] (also see supporting information Table S1). ...
The collation of 913 driftwood samples from across the western Arctic, with spatiotemporal distribution and available provenance data, enabled the production of a high-resolution proxy-based reconstruction of Holocene Arctic Ocean surface current and sea ice dynamics. Regionally bounded, driftwood-based sea ice reconstructions studies suggest spatiotemporally complex past Arctic sea ice extent and movement; however, a large-scale compilation of Holocene Arctic driftwood has not previously been developed. Sparse driftwood in the early Holocene (≥8.2 cal ka B.P.) deglacial period was followed by increased driftwood deposition in the warmer mid-Holocene (8.2–4.2 cal ka B.P.); characterized by an enhanced Transpolar Drift (TPD) ∼7 cal ka B.P., leading to sea ice loss through the Fram Strait. Driftwood incursion peaks show spatial E-W progression from the Eurasian Archipelagos to Greenland and the Canadian Arctic Archipelago, suggesting a progressive shift in the orientation of the TPD on centennial-millennial time scales and intermediate phases in the Arctic Oscillation. Late Holocene cooling (≤4.2 cal ka B.P.) is indicated by increased influx of probably North American Picea via a strengthened Beaufort Gyre (BG) which enhanced sea ice recirculation, starting in the western Arctic and progressing eastward. In recent millennia (<2 cal ka B.P.), a more variable driftwood record alternates between BG and TPD dominance on centennial time scales. To further constrain a spatiotemporal reconstruction of variations in Holocene ocean current and sea ice dynamics, a more definitive determination of driftwood provenance is recommended to build upon the current framework, such as through radiogenic isotope tracing and aDNA analysis.
... Studies in Arctic coastal and marine environments have used the presence, location, species, and age of driftwood to infer the long-term variability of ocean current dynamics, sea-ice conditions, and the occurrence of storm surges (e.g. Reimnitz and Maurer, 1979;Harper 35 et al., 1988;Dyke et al., 1997;Tremblay et al. 1997;Bennike, 2004;Polyak et al., 2010;Nixon et al., 2016;Irrgang et al., 2019). Age control on Holocene driftwood is commonly obtained by radiocarbon ( 14 C) dating and the reported uncalibrated ages may have uncertainties in the order of decades to centuries (e.g. ...
... Funder et al., 2010;Hole and Macias-Fauria, 2017). Modern AMS facilities, however, can provide substantially lower methodological dating uncertainties (Wacker et al., 2010;Nixon et al., 2016;Mason 40 et al., 2020;Fig. S1). ...
Originating from the boreal forest and often transported over large distances, driftwood characterizes many Arctic coastlines. Here we present a combined assessment of radiocarbon (14C) and dendrochronological (ring width) age estimates of driftwood samples to constrain the progradation of two Holocene beach-ridge systems near the Lena Delta in the Siberian Arctic (Laptev Sea). Our data show that the 14C ages obtained on syndepositional driftwood from beach deposits yield surprisingly coherent chronologies for the coastal evolution of the field sites. The dendrochronological analysis of wood from
modern driftlines revealed the origin and recent delivery of the wood from the Lena River catchments. This finding suggests that the duration transport lies within the uncertainty of state-of-the-art 14C dating and thus substantiates the validity of age indication obtained from driftwood. This observation will help to better understand changes in similar coastal environments, and to improve our knowledge about the response of coastal systems to past climate and sea-level changes.
... Driftwood represents a unique record that can provide information on sea ice state over several millennia (Hellmann et al., 2017;Funder et al., 2011;Nixon et al., 2016;Dyke et al., 1997). Driftwood from boreal (Canadian and Siberian) forests enters in the Arctic Ocean via river systems because of natural processes such as shoreline erosion or storms. ...
... This change in driftwood deposit is explained by a reduced BG and a westward shift of the TPD. These results match well with the driftwood records (Bennike and Weidick, 2001;Nixon et al., 2016;Dyke et al., 1997;Hole and Macias-Fauria, 2017). Hole and Macias-Fauria (2017) suggested that the changes in driftwood deposit may be due to relatively large changes in the sea ice circulation. ...
Driftwood is frequently used to estimate past changes of sea ice extent and circulation in the Arctic. Nevertheless, driftwood observations are difficult to interpret because of the potentially complex relation with climate change. In order to determine the origin of the observed changes, we built a driftwood transport model (DTM) simulating the driftwood trajectories from the boreal forest to Arctic coasts. The model is driven by three main variables, which are the sea ice velocity, concentration and the sea surface current velocity that can be derived from observations or climate model outputs (e.g. from a General Climate Model – GCM). Overall, the DTM model agrees with the observations, although this comparison needs to be taken with caution because of the sparse data and the uncertainties of driftwood provenance. Through simulations performed with the DTM model, we confirm the strong influence of the variability of the atmospheric circulation on the spatial driftwood distribution. Model simulations of the Mid-Holocene period driven by six GCMs show that small local changes in sea ice circulation – a westward shift in the Transpolar Drift and a reduced Beaufort Gyre during the Mid-Holocene compared to the present period – suffice to explain the driftwood landing change during the Mid-Holocene, with a non-negligible contribution from reduced sea ice concentration. Consequently, a change in driftwood deposit should not be directly interpreted as large modifications in atmospheric circulation and the complexity of the response of driftwood trajectories to past climate changes clearly highlights the interest of using a model to interpret driftwood records.
... Driftwood in the Arctic was not only a highly important resource for local people in ancient times but still is nowadays [22][23][24]. Additionally, it represents a unique palaeoenvironmental proxy archive that may provide insight into past sea ice conditions and current dynamics over several thousand years [25][26][27][28]. Collection of driftwood samples at different altitudinal levels along Arctic coastlines with subsequent radiocarbon dating, in combination with geomorphological analysis of beach ridges, can enable the reconstruction of past sea ice extent and variation [25,26,[28][29][30]. ...
... Additionally, it represents a unique palaeoenvironmental proxy archive that may provide insight into past sea ice conditions and current dynamics over several thousand years [25][26][27][28]. Collection of driftwood samples at different altitudinal levels along Arctic coastlines with subsequent radiocarbon dating, in combination with geomorphological analysis of beach ridges, can enable the reconstruction of past sea ice extent and variation [25,26,[28][29][30]. Sampling sites in the northern Arctic are characterized by a high probability of finding millennial-old wood samples due to minor human impact [25]. ...
Wood from the boreal forest represents an important resource for paper production and sawmill processing. Due to poor infrastructure and high transportation costs on land, timbers are often transported over long distances along large river systems. Industrial river rafting activities started at the end of the 19th century and were intensified in western Russia and central Siberia from the 1920s to the 1980s. After initial single stem rafting, timber is today mostly floated in ship-guided rafts. Lost wood can be transported further to the Arctic Ocean, where it may drift within sea ice over several years and thousands of kilometers before being deposited along (sub-)Arctic coastlines. Here, we introduce dendro-dated tree-ring width series of 383 driftwood samples from logged timber that were collected along different driftwood-recipient coastlines in Greenland, Iceland and Svalbard. The majority of driftwood is Pinus sylvestris from the southern Yenisei region in central Siberia, whereas Larix sp. and Picea sp. from western Russia and eastern Siberia are rare. Although our results are based on a small sample collection, they clearly show the importance of timber rafting on species, age and origin of Arctic driftwood and indicate the immense loss of material during wood industrial river floating.
... These may include river discharge rates, logging and transport activities, permafrost thawing, floods, wildfires, ice and other dams, sea surface temperatures, surface winds, sea-ice extent and drift, water salinity, speciesspecific floating capacities of wood, as well as ocean currents, such as the Transpolar Drift and the Beaufort Gyre (Hole and Macias-Fauria, 2017;Sander et al., 2021;Tsubouchi et al., 2021). Furthermore, it has been argued that long-term climate and environmental changes have affected the dispersal of Arctic driftwood at different rates and intensities throughout the Holocene (Funder et al., 2011;Nixon et al., 2016). While driftwood was abundant on Ellesmere Island from around 10-6 k years BP, driftwood was particularly sparse in northern Greenland during the Holocene Thermal Maximum around 8-6 k years BP, because of reduced multiyear sea-ice and more open water (Funder et al., 2011). ...
Driftwood supply was a pivotal factor for the Norse expansion in medieval times and still exhibits an essential resource for Arctic settlements. The physical causes and societal consequences of long-term changes in the distribution of Arctic driftwood are, however, poorly understood. Here, we use dendrochronology to reconstruct the age and origin of 289 driftwood samples that were collected at remote shorelines in northeast Iceland. Based on 240 reference tree-ring width chronologies from the boreal forest zone, and an overall provenance success of 73%, we show that most of the driftwood is pine and larch from the Yenisei catchment in central Siberia. Our study reveals an abrupt decline in the amount of driftwood reaching Iceland since the 1980s, which is corroborated by the experience of local farmers and fishers. Despite the direct and indirect effects of changes in both, logging activity across Siberia as well as Arctic Ocean currents, the predicted amount of sea-ice loss under anthropogenic global warming is likely to terminate Iceland's driftwood supply by 2060 CE.
... Examples of coastal and shelf sea-ice reconstructions using foraminifera (together with other proxies) are given in Seidenkrantz (2013) who reviews the potential of foraminifera as sea-ice proxies. Past sea-ice variability has also been studied using driftwood (Funder et al., 2011;Nixon et al., 2016) and bowhead whale remains on glacio-isostatically raised beaches (e.g., Dyke et al., 2006), particularly in areas that are undersampled in marine sediment records, such as the Canadian Arctic. Furthermore, sea-ice histories have been inferred from methane sulphonic acid, bromine and sea salt in ice cores (Criscitiello et al., 2013;Spolaor et al., 2016;Rhodes et al., 2018). ...
Frozen components on land and in the ocean (sea ice, ice sheets, glaciers and permafrost) form the cryosphere, which, together with the ocean, moderates the physical and chemical habitat for life in the Arctic and beyond. Changes in these components, as a response to rapidly warming climate in the Artic, are intensely expressed in the coastal zone. These areas receive increased terrestrial runoff while subject to a changing sea-ice and ocean environment. Proxies derived from marine sediment archives provide long-term data that extend beyond instrumental measurements. They are therefore fundamental in disentangling human-driven versus natural processes, changes and responses. This paper (1) provides an overview of current Arctic cryosphere change, (2) reviews state-of-the-art palaeoecological approaches, (3) identifies methodological and knowledge gaps, and (4) discusses the strengths and future potential of palaeoecology and palaeoceanography to respond to societally-relevant coastal marine ecosystem challenges. We utilize responses to an open survey conducted by the Future Earth Past Global Changes (PAGES) working group Arctic Cryosphere Change and Coastal Marine Ecosystems (ACME). Significant research advancements have taken place in recent decades, including the increasingly common use of multi-proxy (multiple lines of evidence) studies, improved understanding of species-environment relationships, and development of novel proxies. Significant gaps remain, however, in the understanding of proxy sources and behaviour, the use of quantitative techniques, and the availability of reference data from coastal environments. We highlight the need for critical methodological refinement, interdisciplinary collaboration on research approaches, and enhanced communication across the scientific community.
... Larix (larch) is a markedly common genus of conifers throughout Asian boreal forests and is assumed to indicate a Siberian origin. Picea (spruce) is another boreal forest genus of coniferous species very common in North America, and is assumed to signify a North American origin (e.g., Dyke et al., 1997;Eggertsson, 1993;Funder et al., 2011;Häggblom, 1982;Hellmann et al., 2013;Nixon et al., 2016). In North America, Picea was present between 10 and 7 ka north of the Mackenzie Delta, up to 70 km north of the modern treeline (Ritchie & Hare, 1971). ...
We present a 500-year history of naturally felled driftwood incursion to northern Svalbard, directly reflecting regional sea ice conditions and Arctic Ocean circulation. Provenance and age determinations by dendrochronology and wood anatomy provide insights into Arctic Ocean currents and climatic conditions at a fine spatial resolution, as crossdating with reference chronologies from the circum-Arctic boreal forests enables determination of the watershed the driftwood originated from. Sample crossdating may result in a wide range of matches across the pan-boreal region, which may be biased towards regions covered by the reference chronologies. Our study considers alternate approaches to selecting probable origin sites, by weighting scores via reference chronology span and visualising results through spatiotemporal density plots, as opposed to more basic ranking systems. As our samples come from naturally felled trees (not logged or both), the relative proportions of different provenances are used to infer past ocean current dominance. Our record indicates centennial- to decadal-scale shifts in source regions for driftwood incursion to Svalbard, aligning with Late Holocene high variability and high frequency shifts in the Transpolar Drift and Beaufort Gyre strengths and associated fluctuating climate conditions. Driftwood occurrence and provenance also track the northward ice formation shift in peripheral Arctic seas in the past century. A distinct decrease in driftwood incursion during the last 30 years matches the observed decline in pan-Arctic sea ice extent in recent decades. Our new approach successfully employs driftwood as a proxy for Arctic Ocean surface circulation and sea ice dynamics.
... The main conclusion is that the Saqqaq culture in Disko Bay relied mostly on driftwood and, to a small extent, on native woodland ( Fig. 9) (Grønnow, 1996). Even though it is highly likely that forest composition and ocean circulation changed between the period the Saqqaq culture was in Greenland and the Norse period, which would affect the range of taxa drifting to Greenland (Dyke et al., 1997;Alix, 2005;Funder et al., 2011;Nixon et al., 2016), the wood assemblage is remarkably similar to many of the Norse sites, especially GUS, which is geographically closest. The proportion of pine in Qeqertasussuk is similar to Tatsip Ataa and GUS but slightly smaller than in Narsaq and Tasilkulooq. ...
The Norse Greenlanders were dependent on wood for making houses, boats, utensils, tools and as fuel. Due to Greenland's northerly latitude and short, cool summers, the local woody taxa include relatively few species, most of which are low-growing shrubs. Consequently, it has been argued that import of timber was necessary to meet the wood requirements of the Norse Greenlanders. The taxa of archaeological wood assemblages from five Norse sites in Greenland, the episcopal manor Garðar/Igaliku (Ø47), Tatsip Ataa Killeq (Ø172), Tasilikulooq (Ø171), Narsaq (Ø17a) and Gården under Sandet (GUS) were analysed to determine whether the wood was native, import or driftwood. This paper demonstrates that farmers in Greenland used mainly driftwood and native wood, while high-status sites like Igaliku had access to sporadic timber imports from mainland Europe and North America. Furthermore, the proportions of driftwood taxa from the Norse settlements are more or less the same as of Inuit and pre-Inuit cultures in Greenland and the Smith Sound. These results suggest that the Norse Greenlanders were not reliant on imported wood but were in fact mostly self-sufficient in regard to their timber resources.
... W.R. Farnsworth, et al. Earth-Science Reviews 208 (2020) 103249 permanent sea-ice extent (Häggblom, 1982;Nixon et al., 2016;Hole and Macias-Fauria, 2017). Where sea-ice cover is too low no driftwood arrives, while with multiyear sea ice, driftwood is shielded from the shorelines . ...
The Arctic regions are affected by the modern climate change to a greater extent than the global average. This effect is called the Arctic amplification and is reflected in air temperatures rising with double rate and increased precipitation compared to the global average. The climate of Svalbard is strongly related to variations in the atmospheric and oceanic circulation patterns, and the archipelago is, therefore, ideal location to study the climate sensitivity of the Arctic. This dissertation presents research on the Late Pleistocene and Holocene glacial history of Svalbard. Marine, lacustrine and terrestrial archives are assessed in a confined geographical area in northern Wijdefjorden, northern Spitsbergen, and the regional timing of the deglaciation, Holocene Thermal Maximum, Holocene Glacial Minimum as well as the onset of the Neoglacial are identified (Papers I-III). The research focus is on Wijdefjorden, Femmilsjøen and the NW part of the Åsgardfonna ice cap. The results are placed in a regional context and compared to studies across Svalbard. A review of the Holocene glacial history of Svalbard is presented in Paper IV, where all Holocene chronological data from Svalbard are re-calibrated or calculated and gathered in one database. The landforms in the fjord (Paper I) and the lowermost acoustic and sedimentary facies (Papers I-II) are interpreted to be indicative of grounded, warm-based ice occupied the fjord during the Last Glacial. By contrast, Paper III speculates that parts of the terrestrial terrain are similar to forelands of cold-based glaciers in Antarctica, which may have been covered by cold-based and little erosive glacier ice during the Last Glacial. Among the findings are that northern Svalbard deglaciated early. Wijdefjorden is inferred to deglaciate at least prior to 12.4 ± 0.3 cal. ka BP and potentially prior to 14.5 ± 0.3 cal. ka BP. Femmilsjøen deglaciated potentially prior to 16.1 ± 0.3 cal. ka BP. Deglaciation occurred in a stepwise manner and was characterised by fluctuating water temperatures and sea ice cover. Overarching, the Svalbard fjords deglaciated rapidly during the first half of the Early Holocene, however the overall retreat was punctuated by dynamic ice-advances of smaller tributary glaciers. Femmilsjøen was isolated from the marine environment c. 11.4 cal. ka BP. The regional Holocene glacial minimum coincided with the Holocene thermal maximum (between 10.1 ± 0.4 and 3.2 ± 0.2 cal. ka BP), during which time the ice cap Åsgardfonna was small or close to absent. Collectively in Svalbard, the Holocene glacial minimum most likely occurred between 8.0 and 6.0 cal. ka BP. Thus, the Holocene thermal maximum and Holocene glacial minimum in northern Wijdefjorden seems extended compared to the rest of Svalbard. In the fjord, seawater temperatures show a gentle decrease and the sea-ice proxy a gentle increase from c. 6.0 cal. ka BP, but values do not accelerate until c. 0.5 cal. ka BP. In Svalbard, Neoglacial glacier advances occurred generally from 4.0 to 0.5 cal. ka BP and with the Little Ice Age representing the last cold-spell of the Neoglacial. In Femmilsjøen, glacial influence recommenced from 3.2 ± 0.2 cal. ka BP, and glaciers in the catchment reached sizes no smaller than their current extent within c. 1.0 ka. The Holocene climate and glacial variability of Svalbard are strongly coupled to atmospheric and oceanic forcings.
... Ages extend over 12.0 ka BP as the database includes all ages in which error margins fall within the Holocene (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) permanent sea-ice extent (Häggblom, 1982;Funder et al., 2011;Nixon et al., 2016;Hole and Macias-Fauria, 2017). Where sea-ice cover is too low no driftwood arrives, while with multiyear sea ice, driftwood is shielded from the shorelines (Funder et al., 2011). ...
We synthesize the current understanding of glacier activity on Svalbard from the end of the Late Pleistocene (12,000 yrs. before present) to the end of the Little Ice Age (c. 1920 AD). Our glacier history is derived from the SVALHOLA database, the first compilation of Holocene geochronology for Svalbard and the surrounding waters, including over 1,800 radiocarbon, terrestrial cosmogenic nuclide and optically stimulated luminescence ages. Data have been categorized by geological setting, uniformly (re-)calibrated, quality assessed and ultimately used to constrain glacier fluctuations (deglaciation, ice free conditions, glacier re-advances and ice marginal positions). We advance existing knowledge by mapping the extent and distribution of ice-cover during the Holocene glacial maximum and the glacial minimum, as well as present retreat rates (and percentages) within Early Holocene fjord-systems. We discuss the complexities of glacier systems and their dynamics in response to changes in climate. This review provides a holistic state of the art of Holocene glaciers on Svalbard, suitable for orienting future works which address gaps in our current knowledge.
... Despite the fact that our driftwood record is the best replicated for the Arctic until now, the analyses of additional samples from other regions in the Arctic (e.g. where millennial old wood has already been found but not yet dendrochronologically analyzed ;Funder et al., 2011;Nixon et al., 2016;Nixon and England, 2013), still offer a huge potential for building tree-ring chronologies that extend back several millennia. If different origin areas would be found for different time periods over the past millennia, conclusions on variations in ocean currents , as well as sea ice extent (Funder et al., 2011), could be achieved. ...
Arctic driftwood may represent a cross-disciplinary proxy archive at the interface of marine and terrestrial environments, which will likely gain in importance under future global climate change. Circumpolar network analyses that systematically consider species-specific boreal origin areas, transport routes and deposition characteristics of Arctic driftwood, are, however, missing. Here, we present tree-ring width (TRW) measurements of 2412 pine, larch and spruce driftwood samples from Greenland, Iceland, Svalbard, the Faroe Islands, and the Lena Delta in northeastern Siberia. Representing the largest Arctic driftwood TRW compilation, these data are compared against 495 TRW reference chronologies from the boreal forests of Eurasia and North America. The southern Yenisei region is the main source for recent pine driftwood at all Arctic sampling sites, whereas spruce mainly originates in western Russia and central Siberia, as well as in northern North America. Larch driftwood is, for the first time, dendro-provenanced to central and eastern Siberia. A new larch driftwood chronology extends the middle Lena River reference chronology back to 1203 CE. Annually resolved radiocarbon measurements further date six larch driftwood chronologies between 1294 and 2013 CE. Although being highly replicated, our study emphasizes the importance of interdisciplinary research efforts including radiocarbon dating, isotopic tracing and aDNA processing for improving Arctic driftwood provenancing in space and time. If successful, Arctic driftwood studies will contribute to the reconstruction of past boreal summer temperature variations and ocean current dynamics, as well as changes in sea ice extent and relative sea level over the last centuries to millennia.
... The examination of driftwood utilization in Iceland in the past can be problematic, as modern comparative assemblages are heavily influenced by logging (Hellmann et al. 2013) and may not be analogous with past driftwood delivery due to changes in climate, oceanic circulation and forest composition in source areas , Tremblay et al. 1997, Chapin et al. 2004, Alix 2005, Funder et al. 2011, Nixon et al. 2016. However recent work on medieval Icelandic wooden artefact assemblages has indicated a distinct pattern of wood use with a reliance on driftwood (Mooney 2016b), and this pattern may also extend to boat construction and repair. ...
While boat and ship graves are known from across northern Europe, and are particularly associated with the Viking Age, only seven examples of such monuments have been excavated in Iceland. Furthermore, no shipwrecks are known dating from this period in Iceland, and examples of boat timbers preserved by waterlogging are very rare. As such, the mineralized wood remains from these burials comprise the vast majority of direct archaeological evidence currently available for the boats used in daily life in early Iceland. This paper uses taxonomic identification of mineralized wood remains from the Icelandic boat graves, along with comparative data from Europe and Scandinavia, to discuss boat construction and repair in early Iceland, including the possibilities of driftwood utilization and the importation of boats from Norway. The economic and social significance of the practice of boat burial in Iceland is also explored, with regard to the importance of boats as transport and the limited availability of wood suitable for boat construction and repair.
... Modern assemblages of driftwood in Iceland have been shown to be delivered by the Transpolar Drift Stream and derive mostly from central Siberia (Eggertsson, 1993;Hellmann et al., 2013a), while driftwood in the in the Hebrides may arrive from North America via the North Atlantic Current (Dickson, 1992). While modern material from driftwood beaches does provide an indication of the composition of past assemblages, it should be noted that neither forest composition nor patterns of ocean circulation are constant (Chapin et al., 2004;Nixon et al., 2016;Funder et al., 2011;Alix, 2005;Dyke et al., 1997;Tremblay et al., 1997). Changes in either of these could affect the range of taxa found as driftwood in a given region in the past, and should be taken into account where possible in interpretations of archaeological remains. ...
Throughout history, wood has been of key importance to many human communities both as a source of fuel and as material for construction. This applies not only in areas with plentiful woodlands or forests, but also in more marginal island environments where limited native wood resources are available. In such environments, the use of ‘exotic’ timber such as driftwood or imported wood plays a key role in resource provision. The exploration of patterns of use of both native and ‘exotic’ woods in wood-poor environments has great potential to contribute to discussions of resource management and control and human response to landscape change. Using Iceland as a case study, this paper compares wood anatomical analyses of artefact assemblages from across Europe to determine the likely origin of wood (native, imported, drifted) from archaeological sites in the North Atlantic islands, and demonstrates the emergence of an ‘island signature’ in wood utilisation patterns in this region. The paper also highlights the potential pitfalls of the categorisation of wood remains through taxonomic determination, and examines how these obstacles might be overcome in future research.
Originating from the boreal forest and often transported over large distances, driftwood characterizes many Arctic coastlines. Here we present a combined assessment of radiocarbon (14C) and dendrochronological (ring width) age estimates of driftwood samples to constrain the progradation of two Holocene beach-ridge systems near the Lena Delta in the Siberian Arctic (Laptev Sea). Our data show that the 14C ages obtained on syndepositional driftwood from beach deposits yield surprisingly coherent chronologies for the coastal evolution of the field sites. The dendrochronological analysis of wood from modern drift lines revealed the origin and recent delivery of the wood from the Lena River catchment. This finding suggests that the duration of transport lies within the uncertainty of state-of-the-art 14C dating and thus substantiates the validity of age indication obtained from driftwood. This observation will help us better understand the response of similar coastal systems to past climate and sea-level changes.
During the summer 1987 expedition of the polar research vessel‘Polarstern’in the Eurasian Basin of the Arctic Ocean, sea ice at about 84-86°N and 20-30°E was found to have high concentrations of particulate material. The particle-laden ice occurred in patches which often darkened more than half the ice surface at our northernmost positions. Much of this ice appeared to be within the Siberian Branch of the Transpolar Drift stream, which transports deformed, multi-year ice from the Siberian shelves westward across the Eurasian Basin. Lithogenic sediment, which is the major component of the particulate material, may have been incorporated during ice formation on the shallow Siberian seas. Diatoms collected from the particle-rich ice surfaces support this conclusion, as assemblages were dominated by a marine benthic species similar to that reported from sea ice off the coast of northeast Siberia. Based on drift trajectories of buoys deployed on the ice it appears that much of the particle-laden ice exited the Arctic Ocean through the Fram Strait and joined the East Greenland Current. Very different sea ice characteristics were found east of the Yermak Plateau and north of Svalbard and Frans Josef Land up to about 83-84°N. Here sea ice was thinner, less deformed, with lower amounts of lithogenic sediment and diatoms. The diatom assemblage was dominated by planktonic freshwater species. Trajectories of buoys deployed on sea ice in this region indicated a tendency for southward transport to the Yermak Plateau or into the Barents Sea.
Recent findings indicated spruce from North America and larch from eastern Siberia to be the dominating tree species of Arctic driftwood throughout the Holocene. However, changes in source region forest and river characteristics, as well as ocean current dynamics and sea ice extent likely influence its spatiotemporal composition. Here, we present 2556 driftwood samples from Greenland, Iceland, Svalbard, and the Faroe Islands. A total of 498 out of 969 Pinus sylvestris ring width series were cross-dated at the catchment level against a network of Eurasian boreal reference chronologies. The central Siberian Yenisei and Angara Rivers account for 91% of all dated pines, with their outermost rings dating between 1804 and 1999. Intensified logging and timber rafting along the Yenisei and Angara in the mid-20th century, together with high discharge rates, explain the vast quantity of material from this region and its temporal peak ca. 1960. Based on the combined application of wood-anatomical and dendrochronological techniques on a well-replicated data set, our results question the assumption that Arctic driftwood mainly consists of millennial-old larch and spruce. Nevertheless, data from other species and regions, together with longer boreal reference chronologies, are needed for generating reliable proxy archives at the interface of marine and terrestrial environments.
The Devon Island ice cap has been the subject of scientific study for almost half a century, beginning with the first mass balance measurements in 1961. Research on the ice cap was the first to investigate (1) the role of meltwater in seasonal ice-velocity variations on a polythermal Arctic ice cap, (2) the use of air temperature rather than net radiation as a proxy for the energy driving surface melt, and (3) the influence of the changing frequency of specific synoptic weather configurations on glacier melt and mass balance. Other research has included investigations of ice cap geometry, flow dynamics, and mass balance; ice core analyses for records of past climate and contaminant deposition; and studies of changes in ice cap area and volume and their relationship to surface mass balance and ice dynamics. Current research includes ground studies connected to efforts to calibrate and validate the radar altimeter that will be carried by the European Space Agency's (ESA) CryoSat2 satellite, and a major collaborative Canadian International Polar Year (IPY) project focused on the Belcher Glacier, on the northeast side of the ice cap, that examines hydrodynamics of large tidewater glaciers. This paper summarizes our current knowledge of the Devon Island ice cap and identifies some of the outstanding questions that continue to limit our understanding of climate-ice cap interactions in Arctic regions.
This study investigates whether raised beach sequences preserved on emergent coasts of the central Canadian Arctic Archipelago contain a proxy record of past sea-ice conditions and wave intensity. We hypothesize that periods of reduced sea ice (increased open water) expose shorelines to more prolonged and higher wave energy, leading to better-developed beach ridges. Surveys of raised beach sequences on Lowther Island revealed the following patterns: a) high, wide, single- to multicrested barriers backed by deep swales or lagoons characterize both the active and lowest relict shorelines; b) small, narrow, discontinuous ridges of poorly sorted gravel extend from 1.0 to 7.5 m asl, except from 4.5 to 5.0 m asl; c) ridge morphology is similar to the active and first relict ridges between 7.5 and 11 m asl; d) a near-featureless zone with minor terraces and ridges above 11 m extends to above 30 m asl. These distinct morphological and sedimentary units are interpreted as a function of wave climate and thus of summer sea-ice conditions. This model suggests periods of greater wave activity from the present day back about 500 14C years (530 cal BP; Unit A), during a short interval from 1750 to 1600 14C years BP (1750-1450 cal BP; Unit B'), and earlier from 2900 to 2300 14C years BP (3030-2340 cal BP; Unit C). Units B and D are interpreted as the result of more severe ice conditions with lower wave energy from 2300 to 500 14C years BP (2340-530 cal BP) and earlier from more than 5750 to 2900 14C years BP (6540-3030 cal BP). Discrepancies with previously published interpretations of regional sea-ice history may reflect the local nature of the beach proxy record, which implies occurrences of extensive open-water fetch east and west of Lowther Island but cannot be extrapolated to a regional scale. The beach record shows distinct variation through time and provides an alternative window on past summer ice extent in central Barrow Strait.
In the area of Denmark Strait (∼ 66 • N), the two modes of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) are expressed in changes of the northward flux of Atlantic water and the southward advection of po-lar water in the East Iceland current. Proxies from marine cores along an environmental gradient from extensive to lit-tle or no drift ice, capture low frequency variations over the last 2000 cal yr BP. Key proxies are the weight% of calcite, a measure of surface water stratification and nutrient sup-ply, the weight% of quartz, a measure of drift ice transport, and grain size. Records from Nansen and Kangerlussuaq fjords show variable ice-rafted debris (IRD) records but have distinct mineralogy associated with differences in the fjord catchment bedrock. A comparison between cores on either side of the Denmark Strait (MD99-2322 and MD99-2269) show a remarkable millennial-scale similarity in the trends of the weight% of calcite with a trough reached during the Little Ice Age. However, the quartz records from these two sites are quite different. The calcite records from the Denmark Strait parallel the 2000 yr Arctic summer-temperature reconstruc-tions; analysis of the detrended calcite and quartz data re-veal significant multi-decadal–century periodicities superim-posed on a major environmental shift occurring ca. 1450 AD.
Three of the past six summers have exhibited record low sea-ice extent on the Arctic Ocean. These minima may have been dynamically induced by changes in the surface winds. Based on results of a simple model that keeps track of the age of ice as it moves about on the Arctic Ocean, we show that the areal coverage of thick multi-year ice decreased precipitously during 1989-1990 when the Arctic Oscillation was in an extreme ``high index'' state, and has remained low since that time. Under these conditions, younger, thinner ice anomalies recirculate back to the Alaskan coast more quickly, decreasing the time that new ice has to ridge and thicken before returning for another melt season. During the 2002 and 2003 summers this anomalously younger, thinner ice was advected into Alaskan coastal waters where extensive melting was observed, even though temperatures were locally colder than normal. The age of sea-ice explains more than half of the variance in summer sea-ice extent.
The oldest dated driftwood log from northern Greenland is c. 9300 cal. years old, which is about 2000 years younger than the beginning of the last deglaciation and 2000 years younger than the oldest driftwood on Svalbard. Driftwood entry to northern Greenland was rare until 7400 cal. years BP, indicating more severe summer sea-ice conditions than at present. More open water than at present probably characterized the period between 6800 and 5500 cal. years BP, during which time driftwood stranded on the beaches of Nioghalvfjerdsfjorden that is now covered by a floating glacier. In central East Greeland, the occurrence of the extralimital species Mytilus edulis in the time interval from c. 8500 to 6000 cal. years BP indicates more open water than at present, and in northwest Greenland studies of dinoflagellate cysts in a marine core indicate warmer surface waters, and hence less sea ice than at present from 7300 to 3700 cal. years BP.
Varved sediments from Nicolay Lake, Canadian High Arctic, record major summer rainfall events over the last five centuries. Increased incidences of summer rainfall occurred during the coldest periods of the ‘Little Ice Age’ and were strongly clustered in the years immediately following major volcanic events. Comparison of the summer rainfall and proxy air temperature records thus provides a fuller understanding of the nature and causes of natural climate variability in the Arctic. Study of the synoptic conditions associated with the two most recent large summer rainfall events suggests that they are associated with the incursion of cold low-pressure systems from the Arctic Ocean Basin. Volcanic activity may produce atmospheric conditions more conducive to the formation of such low-pressure systems, which generate rainfall at low elevations and summer snowfall at higher elevations, thus explaining the correlation between rainfall and summer snow accumulation recorded in ice cores from high-elevation ice caps.
The primary aim of this paper is to describe and discuss the palaeoclimatic significance of mid-to late-Holocene fields of raised-beach ridges at Matalaniemi and sea-ice-pushed boulders at Kutovaya Bay on the Kola Peninsula. These beach features are interpreted as indicating at least 12 periods of stormy conditions alternating with calmer periods of relatively low sea-surface temperature since about 8000 cal. BP. A consistent chronology of climate change is difficult to establish due to considerable uncertainties attributed to local beach processes and relative sea-level displacements. A tentative interpolated chronology is suggested. At present, terrace formation at Matalaniemi and the absence of sea ice at Kutovaya Bay indicate an intermediate windy and mild type of winter climate.
The global distribution of freshwater transport in the ocean is presented, based on an integration point at Bering Strait, which connects the Pacific and Atlantic oceans via the Artic Ocean. Through Bering Strait, 0.8 × 10⁶ m³ s⁻¹ of relatively fresh, 32.5 psu, water flows from the Pacific into the Arctic Ocean. Baumgrtner and Reichel's tabulation of the act gain of freshwater by the ocean in 5° latitude intervals is then integrated from the reference location at Bering Strait to yield the meridional freshwater transport in each ocean. Freshwater transport in the Pacific is directed northward at nearly all latitudes. In the Atlantic, the freshwater transport is directed southward at all latitudes, with a small southward freshwater transport out of the Atlantic across 35°S. Salt transport, which must be considered jointly with the freshwater transport, is northward throughout the Pacific and southward throughout the Atlantic (in the same direction as the freshwater flux) and is equal to the salt transport through the Bering Strait. The circulation around Australasia associated with the poorly known Pacific-Indian throughflow modifies the above scenario only in the South Pacific and Indian oceans. A moderate choice for the throughflow indicates that it dominates the absolute meridional fluxes of freshwater and salt in these oceans. The global freshwater scheme presented here differs markedly from earlier interpretations and suggests the need for a careful assessment of the treatment of ocean freshwater and salt transports in inverse, numerical, and climate models.
The area and volume of sea ice in the ArcticOcean is decreasing, with some predictingice-free summers by 2100 A.D. Johannessenet al., 2004. The implications ofthese trends for transportation and ecosystemsare profound; for example, summershipping through the Northwest Passagecould be possible, while loss of sea icecould cause stress for polar bears. Moreover,global climate may be affected throughalbedo feedbacks and increased sea ice productionand export. With more open water,more new sea ice forms in winter, whichmelts and/or gets exported out of the Arctic.
A total of 276 driftwood samples from Wijdefjorden on the northern coast of Spitsbergen were den-drochronologically analysed and compared with results from a similar study on driftwood from Isfjorden. The composition and origin of the driftwood from the two places differ. Whereas Larix is almost absent in the Isfjorden driftwood, it comprises 25% of the Wijdefjorden collection. The Isfjorden driftwood has its main origin in the White Sea region and the dates of the driftwood concentrate around the period from 1950 to 1979, with only a few dates from the period 1910 to 1950. The Wijdefjorden driftwood has two main origins: Siberia and the White Sea region. The dates of the White Sea components of the Wijdefjorden driftwood are concentrated mainly in the period 1910-1950. The dates of the Siberian (Yenisey) components of the Wijdefjorden driftwood are concentrated in the period 1950–1979. It can be argued that during the time period from ca. 1910 to 1950 the activity of a warm northerly flowing current along the western coast of Spitsbergen was stronger, transporting White Sea driftwood all the way to the Wijdefjorden area. However, after ca. 1950 the input of White Sea driftwood decreased, and the relative importance of the Siberian component increased. These results fit well with the climatic records from Svalbard, showing a warm regime during the first half of this century due to increased activity of the warm West Spitsbergen Current along the western coast of Spitsbergen. After ca. 1950, the influx of Atlantic Water became weaker, the climate became colder and the relative occurrences of Siberian driftwood transported by the Transpolar Current increased on the northern coast of the Svalbard archipelago.
As part of a general study of arctic driftwood, 206 samples of driftwood logs from the Mackenzie delta area were analyzed by dendrochronological methods (tree-ring studies). The aim was to detect the origin of the wood. Three forest stands in the delta were also sampled, and tree-ring chronologies were constructed. The Mackenzie driftwood can be divided into four groups: 1) driftwood originating from the upper Mackenzie delta with individual logs having up to 600 tree rings, 2) driftwood originating near the southern limit of the delta, 3) wood with relatively few tree rings with possible origin in the Liard River drainage area, and 4) driftwood samples not datable with any available chronologies. Three driftwood samples from the coast of Greenland could be correlated with tree-ring chronologies from the Mackenzie delta area and another three were correlated with chronologies from Alaska. American driftwood has not been detected in collections from Svalbard and Iceland, although more than 200 samples have been analyzed from each area.
25 ¹⁴C dates from the coast of Melville Island show that there has been up to 100m of Holocene emergence. The Winter Harbour moraine on the S coast is thought to mark the maximum northward advance of the Laurentice Ice. However, emergence for this area appears to be essentially complete, whereas the NE coast is still recovering at a rate of approximately 0.35 cm/yr. Ice cover in the region to the NE must, therefore, have been thicker and/or lasted longer than in the peripheral areas of the Laurentide Ice, lending support to the concept of an Innuitian Ice Sheet, rather than local ice masses over the central Queen Elizabeth Islands. This ice sheet may have had a thermal regime below the pressure melting point, thus depriving the ice of much of its erosive and depositional capabilities, but with a sufficient mass to account for the observed pattern of emergence. -from Authors
Both the 2-L counter, described in GSC I, and the 5-L counter (GSC IV) were operated routinely during the past year. Approximately one-half of the determinations reported here were obtained from each counter. The 5-L counter was operated mainly at 1 atm.
For more than a year, age calculations have been carried out monthly by an I.B.M. 1620 computer. If the background, standard, and sample counts during a month conform to statistical laws, they are entered on sheets together with their respective counting times and sample identifications and sent to the computing center for processing.
During the past year, 1969-1970, both the 2-L (Dyck and Fyles, 1962) and 5-L (Dyck et al. , 1965) counters were routinely operated. A 1-L counter was finally constructed with acceptable characteristics (see description below) and was operated in July in place of the 5-L counter. The 2-L counter was operated exclusively at 2 atm. The 5-L counter was operated at 1 atm, except for October and November, 1969, when it was operated at 4 atm. The 1-L counter was operated at 1 atm.
Describes a prehistoric dwelling found at McCormick Inlet in 1962. Location of the site at 1.75 m above high water and its age, estimated at 1150-1740 yr from radiocarbon dating of moss, indicate negligible land emergence during the last one and a half millennia. Prehistoric sites recorded by other explorers on the island are also noted and mapped.
Reports on a Dorset Eskimo site discovered by Henoch, qv. Architectural features of the dwelling and the artifacts collected are described. The large size of the stone tools (illus), and lack of some customary Dorset facts are unusual. The site is on the western periphery of the known range of Dorset culture, and further work may elucidate Dorset-Alaskan relationships.
Postulations on the existence of forest refugia in parts of Beringia during the last glacial have been, in large part, based on ambiguous evidence. Existing data on radiocarbon-dated and identified fossil wood and macrofossils from Alaska and northwest Canada are synthesized here and are augmented by results of palynological studies in an effort to show the persistence of some, and total extinction of other, tree and large shrub species. Possible dispersal routes taken by species that reinvaded Beringia in postglacial times are also reconstructed from the fossil record. Macrofossil and pollen evidence, when combined with climatic factors, makes cottonwood a good candidate for survival during the last glacial. Larch and aspen are also candidates, though the evidence for them is less positive. Pollen and macrofossils of alder are very scarce in deposits of the last glacial age, and if it survived at all, it was probably in very isolated vegetatively reproducing clones. Shrub birch may have been present in Beringia, but tree birch probably was reintroduced during the Holocene. Spruce also appears to have been absent in Alaska from about 30,000 to 11,500 yr ago and probably reinvaded Beringia from a refugium south of the Laurentide ice sheet.
The amount and type of driftwood logs on raised beaches in Svalbard probably indicate variations in sea ice conditions through time in the Arctic Ocean. This idea is based on the fact that wood floating in water has a limited buoyancy. The Pacific Gyral has a clockwise circulation in the Beaufort Sea. There are large variations in the rate of drift of this circulation, but the average speed is probably 700-800 km/year.-from Author
More than 70 samples of Holocene driftwood between present sea level and the marine limit are plotted on an emergence curve from Clements Markham Inlet (82°40′N). Three periods of driftwood abundance and sparsity are recognized. These are interpreted as indications of climatically induced changes in summer sea ice conditions. Period 1 extends from initial driftwood entry ca. 8900 BP until ca. 4200 BP. During this period driftwood penetration increases with greatest abundance (= reduced summer sea ice) ca. 6000 to 4200 BP. During Period 2 (ca. 4200 to 500 BP) driftwood penetration is sparse whereas in Period 3 (<500 BP) driftwood bordering the present shoreline exceeds all the samples in the previous periods. Driftwood dates from elsewhere in the Canadian and Greenland High Arctic show similar periods. In Clements Markham Inlet the initiation of abundant driftwood penetration corresponds with the deposition in marine sediments of fossil bryophytes (25 species) dated 6400 BP. This increased plant productivity is also interpreted as indicating summer warmth/higher precipitation associated with the greater open water. Accompanying these bryophytes is the disjunct marine pelecypod Limatula (Lima) subauriculata which presently has a subarctic-boreal distribution. This paleoenvironmental information is discussed in relation to Holocene ice core records and the history of Arctic Ocean sea ice stability.
Age determinations on marine mollusks indicate that the northwestern part of Jones Sound became open to the sea more than 9000 conventional radiocarbon years ago. The presence of postglacial marine features at elevations of up to 130 m near Cape Storm, Ellesmere Island, shows that a significant thickness of glacier ice was present in this area, and the differential uplift of pumice and other materials associated with raised beaches provides convincing evidence that the former ice cover was thicker to the west and to the north. Numerous cross-checks have shown that in such an Arctic environment the organic (collagen) fraction of whale bones gives reliable results, as opposed to the bone apatite fraction, which commonly yields ages that are too young. Marine mollusks also are reliable for 14C age determinations, and the evidence available from areas of carbonate rocks in the Queen Elizabeth Islands suggests that the ages of marine mollusks are no more than 350 years older than the ages of contemporaneous terrestrial plants. Near Cape Storm over fifty 14C age determinations on driftwood, whale bone, and marine mollusks have permitted the construction of a curve showing the pattern of emergence over the past 9000 to 9500 years. Emergence between 9000 and 8000 years ago proceeded at a rate of 7 m/century, and over one-half of the total emergence (70 m out of 130 m) since the initial incursion of the sea took place during this interval. By 6500 to 4500 years ago emergence had slowed to 0.8 m/century, and for the last 2400 years it has averaged <0.3 m/century. The age determinations are sufficiently numerous and closely-spaced, especially between 6500 and 4400 years B. P., to indicate that fluctuations of sea level have not exceeded amplitudes of 2 m or periods >500 years. The concentration of the pumice and the nature of the features associated with it suggest that its deposition may be related to: 1) a eustatic rise close to 5000 years ago; 2) a period of more open water, when wave action and storm surges would have been more effective; 3) a combination of these two factors. The formation of the strandline where the pumice occurs is not believed to be related to a slowing-down or cessation of uplift due to the thickening of ice caps and glaciers.
Satellite data reveal unusually low Arctic sea ice coverage during the
summer of 2007, caused in part by anomalously high temperatures and
southerly winds. The extent and area of the ice cover reached minima on
14 September 2007 at 4.1 × 106 km2 and 3.6
× 106 km2, respectively. These are 24% and
27% lower than the previous record lows, both reached on 21 September
2005, and 37% and 38% less than the climatological averages.
Acceleration in the decline is evident as the extent and area trends of
the entire ice cover (seasonal and perennial ice) have shifted from
about -2.2 and -3.0% per decade in 1979-1996 to about -10.1 and -10.7%
per decade in the last 10 years. The latter trends are now comparable to
the high negative trends of -10.2 and -11.4% per decade for the
perennial ice extent and area, 1979-2007.
Recent sampling of deglacial and postglacial raised marine sediments across Melville and Eglinton islands in the western Canadian High Arctic yielded over 200 new radiocarbon dates on molluscs, driftwood and other organic materials. From this database, eight relative sea-level curves and an isobase map for the 9.5 cal ka BP shoreline were constructed. The forms, chronology and pattern of the relative sea-level curves across the study area reflect the complex glacial history of this region, including the asynchronous retreat of the formerly coalescent Laurentide and Innuitian Ice Sheets. Zone I relative sea-level curves, which show continuous emergence to present, were observed in areas closer to greater Last Glacial Maximum ice sheet loading; at more distal sites, transitional Zone I/II curves display emergence followed by submergence in the mid- to late-Holocene (still ongoing) related to forebulge migration and collapse. An independent record of late Holocene submergence is provided by radiocarbon-dated driftwood, which is accumulating at modern sea level due to re-deposition during transgression. Geomorphic evidence of submergence at the modern coastline is widespread but does not distinguish areas that experienced a late Holocene lowstand and subsequent transgression from those that are currently at their lowstand. Of special interest are the relative sea-level histories of two areas that experienced earlier deglaciation by the Laurentide Ice Sheet, while remaining in the peripheral depression of the more stable and adjacent Innuitian Ice Sheet The flat-topped relative sea-level curves from these sites appear to record unusually slow rates of glacioisostatic emergence for similar to 1500 years immediately following deglaciation. The relative sea-level data presented in this paper provide important comparisons for sea level models, which have been shown to fit poorly with previously published data from this region.
Analyses of crystal size, bubble content, oxygen isotope ratio, specific electrolytic conductivity, and the distribution of firn and dirt layers in a core, 121.2 m long, from surface to bedrock near the highest point of the Meighen Ice Cap, leads to the following outline of the ice cap's history. The ice cap, which has always been stagnant, originated in the cold period that followed the postglacial Climatic Optimum. After initial growth came a period of negative mass balance in which the area and thickness of the ice cap diminished and the surface slope at the core site steepened. The end of this period, at least 600 y.a., is marked by a discontinuity at 54 m depth in the core; above this level, the values of most parameters differ significantly from their values below. There followed a period of growth by the end of which, some 80 y.a., the ice cap had attained its maximum thickness; this period included the coldest interval in the ice cap's history. Ablation has predominated since then and up to 13 m of ice have been lost at the core site. This history resembles that of the Ward Hunt Ice Shelf.
Earlier studies in Alaska and northwest Canada have shown inconsistent evidence for the expected northward extension of the Arctic tree line during the Hypsithermal Interval. Only megafossil evidence has supported this suggestion; the palynological findings have been inconclusive. The Tuktoyaktuk Peninsula, in the Northwest Territories of Canada, offers critical sites for studies of late-Pleistocene ecology, because of its geological, biotic, and climatological features. Palynological and megafossil evidence is presented from sites on the Tuktoyaktuk Peninsula, indicating northward advance of the Arctic tree line during the period 8500-5500 B.P. Relative pollen frequencies of a core of lake sediment suggest a late-Pleistocene sequence as follows: 12,900-11,600 dwarf birch tundra; 11600-8500 forest tundra; 8500-5500 closed-crown spruce-birch forest; 5500-4000 tall shrub tundra; 4000-present dwarf birch heath tundra. These results suggest that during the Hypsithermal Interval the Arctic Front (July position) was further north, over the Beaufort Sea, a displacement from its present position of about 350 km. The Tuktoyaktuk Peninsula, presently occupied by tundra, and dominated by the Arctic airstream in July, was apparently under forest, with warm, moist Pacific air during the Hypsithermal Interval.
Driftwood appears to be absent in the Beaufort Gyre but abundant in parts of the Transpolar Drift (TPD), which crosses the Arctic Ocean from the Chukchi Sea to the vicinity of northeastern Greenland. Nearly 300 radiocarbon dates on Holocene driftwood from the Canadian Arctic Archipelago reveal two regions with contrasting histories of driftwood incursion: the region accessible to wood brought into Baffin Bay by the West Greenland Current and the rest of the archipelago, which receives wood from the Arctic Ocean. We hypothesize that when the TPD was deflected westward along northern Greenland, wood was delivered widely to the Canadian Arctic Archipelago; when the TPD exited entirely through Fram Strait via the East Greenland Current, little or no wood was delivered to most of the archipelago, but some continued into Baffin Bay via the West Greenland Current. A split TPD delivered wood to both regions. The regional driftwood incursion histories exhibit multiple maxima and minima that can be explained by this hypothesis. The Larix to Picea ratio of wood arriving in the Canadian Arctic Archipelago has also changed through time. This may indicate varying contributions from Russian versus North American sources, which in turn may indicate variable mixing of wood en route. The inferred discharge paths of the TPD were apparently stable for intervals ranging from several millennia to centuries or perhaps only decades. The last major switch broadly correlates with the onset of Neoglaciation. Variations in the path and strength of the TPD may have important oceanographic and climatic consequences downstream in the North Atlantic Ocean.
Different Holocene sea-ice drift patterns in the Arctic Ocean have been hypothesized by Dyke et al. from radiometric analyses of driftwood collected in the Canadian Arctic Archipelago. A dynamic-thermodynamic sea-ice model is used to simulate the modes of Arctic Ocean ice circulation for different atmospheric forcings, and hence determine the atmospheric circulations which may have accounted for the inferred ice drift patterns. The model is forced with the monthly mean wind stresses from 1968 (a year with very large ice export) and 1984 (very low ice export), two years with drastically different winter sea level pressure patterns and with different phases of the NAO index. The simulations show that for the 1968 wind stresses, a weak Beaufort Gyre with a broad Transpolar Drift Stream (TDS) shifted to the east are produced, leading to a large ice export from the Arctic. Similarly, the 1984 wind stresses lead to an expanded Beaufort Gyre with a weak TDS shifted to the west and a low ice export. These results correspond to the patterns inferred by Dyke et al. Based on the simulations, the driftwood record suggests that for centuries to millennia during the Holocene, the high latitude average atmospheric circulation may have resembled that of 1968, 1984 and today's climatology, with abrupt changes from one state to the other.
Existing information concerning the pack ice and relevant climate variables of the Canadian Arctic Archipelago north of Parry Channel is summarized. This knowledge is enhanced by newly available data on ice thickness derived from 123,703 drill holes completed during the 1970s. Pack ice in this area is a mix of multiyear, second-year, and first-year ice types, with the latter subordinate except in the southeast. Ice remains land fast for more than half the year, and summertime ice concentration is high (7-9 tenths). In a typical year, less than 20% of the old ice and 50% of the first-year ice melt. There are large interannual fluctuations in ice coverage and some suggestion of a decadal cycle. The average ice thickness in late winter is 3.4 m but subregional means reach 5.5 m. The pack is a mix of two populations, one consisting largely of multiyear ice imported from the zone of heavy ridging along the periphery of the Beaufort gyre and the other consisting of a mix of relatively undeformed first-year, second-year, and multiyear ice types that grow and age within the basin. The ice of the Sverdrup Basin is strongly influenced by a flux of heat (approximately 10 W m-2) that originates in the Atlantic-derived waters of the Arctic Ocean. The drift of ice through the basin is controlled in the present climate by the formation of stable ice bridges across connecting channels. The drift is episodic. Relaxation of these controls in a warmer climate may cause deterioration in ice conditions in Canadian Arctic waters.
Data collected by the International Arctic Buoy Programme from 1979 to
1998 are analyzed to obtain statistics of sea level pressure (SLP) and
sea ice motion (SIM). The annual and seasonal mean fields agree with
those obtained in previous studies of Arctic climatology. The data show
a 3-hPa decrease in decadal mean SLP over the central Arctic Ocean
between 1979-88 and 1989-98. This decrease in SLP drives a cyclonic
trend in SIM, which resembles the structure of the Arctic Oscillation
(AO).Regression maps of SIM during the wintertime (January-March) AO
index show 1) an increase in ice advection away from the coast of the
East Siberian and Laptev Seas, which should have the effect of producing
more new thin ice in the coastal flaw leads; 2) a decrease in ice
advection from the western Arctic into the eastern Arctic; and 3) a
slight increase in ice advection out of the Arctic through Fram Strait.
Taken together, these changes suggest that at least part of the thinning
of sea ice recently observed over the Arctic Ocean can be attributed to
the trend in the AO toward the high-index polarity.Rigor et al. showed
that year-to-year variations in the wintertime AO imprint a distinctive
signature on surface air temperature (SAT) anomalies over the Arctic,
which is reflected in the spatial pattern of temperature change from the
1980s to the 1990s. Here it is shown that the memory of the wintertime
AO persists through most of the subsequent year: spring and autumn SAT
and summertime sea ice concentration are all strongly correlated with
the AO index for the previous winter. It is hypothesized that these
delayed responses reflect the dynamical influence of the AO on the
thickness of the wintertime sea ice, whose persistent `footprint' is
reflected in the heat fluxes during the subsequent spring, in the extent
of open water during the subsequent summer, and the heat liberated in
the freezing of the open water during the subsequent autumn.
Numerous studies have reported decreases in Arctic sea‐ice cover over the past several decades and General Circulation Model (GCM) simulations continue to predict future decreases. These decreases — particularly in thick perennial or multi‐year ice (MYI) — have led to considerable speculation about a more accessible Northwest Passage (NWP) as a transit route through the Canadian Arctic Archipelago (CAA). The Canadian Ice Service Digital Archive (CISDA) is used to investigate dynamic import/export and in situ growth of MYI within the western CAA regions of the NWP from 1968 to 2006. This analysis finds that MYI conditions in the western CAA regions of the NWP have remained relatively stable because the M'Clintock Channel and Franklin regions continuously operate as a drain‐trap mechanism for MYI. Results also show that in addition to the Queen Elizabeth Islands (QEI) region, the Western Parry Channel and the M'Clintock Channel are also regions where a considerable amount of MYI forms in situ and combined with dynamic imports contributes to heavy MYI conditions. There is also evidence to suggest that more frequent dynamic import of MYI appears to have occurred since‐1999 compared to the formation of more MYI in situ before 1999. As a result, the drain‐trap mechanism that has historically maintained heavy MYI conditions in the NWP is perhaps operating faster now than it was in the past. Based on the 38‐year MYI record examined in this study, it is likely that the mechanisms operating within the western CAA regions of the NWP can facilitate the continued presence of MYI for quite some time.
Approximately 90% of Canada's ocean coastline is affected by seasonal or multiyear sea ice and winter ice develops on most lakes. Recent studies of ice effects in the shore zone have included investigations of ice-congested and protected shores in the north-west Canadian Arctic Archipelago, processes involved in the construction by ice of large shore ridges in the same region, direct ice scour and enhanced hydrodynamic scour in the presence of ice (strudel scour and ice wallow), particularly as potential hazards to buried pipelines in the Beaufort Sea, and the dynamics of boulder-strewn tidal flats and boulder barricades in eastern Canada. The extent and frequency of shore nourishment by ice and details of the processes involved, including die relative importance of ride-up versus pile-up, remain important research questions. Reports emphasizing the contribution of ice rafting to shoreface retreat along the Alaskan coast of the Beaufort Sea suggest the need for quantitative studies of this phenomenon in Canada, in particular with respect to prodelta sedimentation at the mouth of the Mackenzie River. The coastal zone in the Beaufort Sea is particularly sensitive to climate change through effects on thermokarst processes, rising sea level, the relation between ice cover and wave energy through fetch limitation, and potential changes involving ice dynamics and freeze-up processes.
The bowhead whale (Balaena mysticetus) is a planktivore of the baleen group of whales adapted to live in the loose edges of the north polar sea ice. Its annual migrations roughly track the advance and retreat of the floe edge. The distribution and radiocarbon ages of bowhead subfossils in the Canadian Arctic Archipelago show that the range of the whale has expanded and contracted abruptly several times over the last 10.5 thousand years (ka). Each expansion or contraction was followed by nearly stable conditions that persisted for millennia. These changes in the geographic range of the bowhead are defined by > 400 radiocarbon dates. The paleo-ranges are the basis for reconstructing summer sea-ice minima. Using this criterion, postglacial time is divided into four intervals: (1) 10.5-8.5 ka B.P.—A large bowhead population extended in the summer all the way to retreating glacier margins and ultimately from the Beaufort Sea to Baffin Bay; meltwater-driven outflows probably cleared the inter-island channels of sea ice; this interval terminated when the present interglacial circulation pattern was established; (2) 8.5-5 ka B.P.—Bowheads were excluded from most of the archipelago because the channels failed to clear of sea ice; summer sea-ice conditions for most of this time were more severe than during historical times; (3) 5-3 ka B.P.—Bowheads reoccupied the central channels of the Arctic Islands, and their range extended beyond historical limits; and (4) 3-0 ka B.P.—Sea ice excluded whales from the central channels, as it does today. This paleoenvironmental record based on bowhead whale distributions is more complex than that revealed in the δ18O, conductivity or the percent-melt records of the Devon and Agassiz ice cores. A reconciliation of the two data sets may indicate the following general summer climatic conditions: 10-8 ka B.P.—warm summers with maximum postglacial warmth; 8-5 ka B.P.—cool, dry summers; 5-3 ka B.P.—cool, wet summers; 3-0 ka B.P.—cold, dry summers.
In 1970, a major storm surge caused by gale-force westerly winds inundated low-lying tundra plains and deltas as far as 5000 m inland and left a driftwood line as much as 3.4 m above normal sea level along the Beaufort Sea coast of Alaska. The height of the surge followed a predictable pattern and was highest along windward-facing shorelines. Coastal retreat and thermoerosion are greatly accelerated on such west-facing shores with eastward sediment transport opposite to normal littoral drift. Evidence suggests an approximate 100-year recurrence interval for similar surges, with potential for damaging the developing oil fields on the North Slope.
The Beaufort Formation, in its type area on Prince Patrick Island, is a single lithostratigraphic unit, a few tens of metres thick, consisting of unlithified sandy deposits of braided rivers. Organic beds in the sand have yielded more than 200 species of plants and insects and probably originated during the Pliocene, when the area supported coniferous forest. This Beaufort unit forms the thin eastern edge of a northwest-thickening wedge of sand and gravel beneath the western part of the island. These largely unexposed beds, up to several hundred metres thick, include the Beaufort unit and perhaps other older or younger deposits. On the islands northeast and southwest of Prince Patrick Island (Meighen Island to Banks Island), the name Beaufort Formation has been applied to similar deposits of late Rrtiary age. Most recorded Beaufort beds on these islands are stratigraphically and paleontologically equivalent to the "type" Beaufort, but a few sites that have been called Beaufort (such as Duck Hawk Bluffs and the lower unit at Ballast Brook, on Banks Island) differ stratigraphically and paleontologically from the "type" Beaufort. This paper recommends that these deposits (probably middle Miocene) and others like them be assigned new stratigraphic names and not be included in the Beaufort Formation as now defined. Informal names Mary Sachs gravel (Duck Hawk Bluffs) and Ballast Brook beds are proposed as an initial step. Formal use of the name Beaufort Formation should be restricted to the western Arctic Islands.
Twenty-five radiocarbon dates from the coast of Melville Island show that there has been up to 100 m of Holocene emergence. This evidence of post-glacial rebound suggests there was significant late-Wisconsin glacier cover on or near the island. The Winter Harbour moraine on the south coast is thought to mark the maximum northward advance of the Laurentide Ice. However, emergence for this area appears to be essentially complete, whereas the northeast coast is still recovering at a rate of approximately 0.35 cm/yr. Ice cover in the region to the northeast must, therefore, have been thicker and/or lasted longer than in the peripheral areas of the Laurentide Ice, lending support to the concept of an Innuitian Ice Sheet, rather than local ice masses over the central Queen Elizabeth Islands. Unfortunately, there is an absence of fresh glacial landforms and stratigraphy that can be attributed to the Innuitian Ice Sheet. We suggest that this ice sheet may have had a thermal regime below the pressure melting point, thus depriving the ice of much of its erosive and depositional capabilities, but with a sufficient mass to account for the observed pattern of emergence.
The recent rapid decline in Arctic sea ice cover has increased the need
to improve the accuracy of the sea ice component in climate models and
to provide detailed long-term sea ice concentration records, which are
only available via proxy data. Recently, the highly branched isoprenoid
IP25, identified in marine sediments underlying seasonal sea
ice, has emerged as a potential sea ice specific proxy for past sea ice
cover. We tested the reliability of this biomarker as a sea ice proxy
against observational sea ice data (sea ice concentrations from the
global HadISST1 database) and against a more established sea ice proxy
(sea ice diatom abundance in sediments) in the South-West (SW) Labrador
Sea. Furthermore, our study location at the southern margin of Arctic
sea ice drift provided a new environmental setting in which to further
test the novel PIP25 index. Our two study sites are located
North-East (NE) and South-East (SE) of Newfoundland where box cores
covering the last ca 100-150 years were collected. IP25
concentrations are nearly an order of magnitude higher and sea ice
diatoms more abundant in sediments from NE of Newfoundland, where sea
ice prevails 2-4 months per year compared to the sediments SE of
Newfoundland, where conditions are generally ice-free year round. The
IP25 fluxes NE of Newfoundland agree well with multi-decadal
North Atlantic Oscillation (NAO) trends in the study area, which in
previous studies have been shown to affect the climatic and sea ice
conditions in the region. When assessed against observational sea ice
data, IP25 appears to be a more sensitive indicator of sea
ice variability in this setting compared to sea ice diatoms and proved
to be a robust and reliable proxy for reconstructing low-frequency
variability in past sea ice concentrations. The PIP25 index
results clearly differ from the observed sea ice data underlining that
caution needs to be exercised when using the index in different
environmental settings.
[1] From 1953 to 2006, Arctic sea ice extent at the end of the melt season in September has declined sharply. All models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) show declining Arctic ice cover over this period. However, depending on the time window for analysis, none or very few individual model simulations show trends comparable to observations. If the multi-model ensemble mean time series provides a true representation of forced change by greenhouse gas (GHG) loading, 33–38% of the observed September trend from 1953–2006 is externally forced, growing to 47–57% from 1979–2006. Given evidence that as a group, the models underestimate the GHG response, the externally forced component may be larger. While both observed and modeled Antarctic winter trends are small, comparisons for summer are confounded by generally poor model performance.