| 1. |
- Andin, Caroline, et al.
(författare)
-
Synoptic variability of extreme snowfall in the St. Elias Mountains,Yukon, Canada
- 2015
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Konferensbidrag (refereegranskat)abstract
- Glaciers in the Wrangell and St. Elias Mountains (Alaska and Yukon) are presently experiencing some of thehighest regional wastage rates worldwide. While the effect of regional temperatures on glacier melt rates in thisregion has been investigated, comparatively little is known about how synoptic climate variations, for example inthe position and strength of the Aleutian Low, modulate snow accumulation on these glaciers. Such informationis needed to accurately forecast future wastage rates, glacier-water resource availability, and contributions tosea-level rise. Starting in 2000, automated weather stations (AWS) were established in the central St-EliasMountains (Yukon) at altitudes ranging from 1190 to 5400 m asl, to collect climatological data in support ofglaciological research. These data are the longest continuous year-round observations of surface climate everobtained from this vast glaciated region. Here we present an analysis of snowfall events in the icefields of theSt-Elias Mountains based on a decade-long series of AWS observations of snow accumulation. Specifically,we investigated the synoptic patterns and air mass trajectories associated with the largest snowfall events (> 25cm/12 hours) that occurred between 2002 and 2012. Nearly 80% of these events occurred during the cold season(October-March), and in 74 % of cases the precipitating air masses originated from the North Pacific south of50N. Zonal air mass advection over Alaska, or from the Bering Sea or the Arctic Ocean, was comparativelyrare (20%). Somewhat counter-intuitively, dominant surface winds in the St. Elias Mountains during highsnowfall events were predominantly easterly, probably due to boundary-layer frictional drag and topographicfunneling effects. Composite maps of sea-level pressure and 700 mb winds reveal that intense snowfall eventsbetween 2002 and 2012 were associated with synoptic situations characterized by a split, eastwardly-shifted orlongitudinally-stretched Aleutian Low (AL) having an easternmost node near the Kenai Peninsula, conditionsthat drove a strong southwesterly upper airstream across the Gulf of Alaska towards the coast. Situations with asingle-node, westerly-shifted AL were comparatively rare. The spatial configuration of the synoptic AL pressurepattern appears to play a greater role in determining snowfall amount in the central St. Elias Mountains than dopressure anomalies within the AL. The estimated snowfall gradient from coastal Alaska to the central St. EliasMountains during intense snowfall events averaged +2.0 0.7 mm/km (SWE), while the continental-side gradientfrom the mountains towards the Yukon plateau averaged -3.3 0.9 mm/km (SWE). The findings presented herecan better constrain the climatic interpretation of long proxy records of snow accumulation variations developedfrom glacier cores drilled in the St. Elias Mountains or nearby regions.
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| 2. |
- Barbaro, E., et al.
(författare)
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Measurement report: Spatial variations in ionic chemistry and water-stable isotopes in the snowpack on glaciers across Svalbard during the 2015-2016 snow accumulation season
- 2021
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:4, s. 3163-3180
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Tidskriftsartikel (refereegranskat)abstract
- The Svalbard archipelago, located at the Arctic sea-ice edge between 74 and 81 degrees N, is similar to 60% covered by glaciers. The region experiences rapid variations in atmospheric flow during the snow season (from late September to May) and can be affected by air advected from both lower and higher latitudes, which likely impact the chemical composition of snowfall. While long-term changes in Svalbard snow chemistry have been documented in ice cores drilled from two high-elevation glaciers, the spatial variability of the snowpack composition across Svalbard is comparatively poorly understood. Here, we report the results of the most comprehensive seasonal snow chemistry survey to date, carried out in April 2016 across 22 sites on seven glaciers across the archipelago. At each glacier, three snowpits were sam- pled along the altitudinal profiles and the collected samples were analysed for major ions (Ca2+, K+, Na+, Mg2+, NH4+, SO42, Br-, Cl-, and NO3-) and stable water isotopes ( ffi18O, delta H-2). The main aims were to investigate the natural and anthropogenic processes influencing the snowpack and to better understand the influence of atmospheric aerosol transport and deposition patterns on the snow chemical composition. The snow deposited in the southern region of Svalbard is characterized by the highest total ionic loads, mainly attributed to sea-salt particles. Both NO3 and NH4+ in the seasonal snowpack reflect secondary aerosol formation and post-depositional changes, resulting in very different spatial deposition patterns: NO3 has its highest loading in northwestern Spitsbergen and NH4+ in the south-west. The Br enrichment in snow is highest in north-eastern glacier sites closest to areas of extensive sea-ice coverage. Spatial correlation patterns between Na+ and delta O-18 suggest that the influence of long-range transport of aerosols on snow chemistry is proportionally greater above 600-700ma.s.l.
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| 3. |
- Baykal, Yunus
(författare)
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Source and age of late Quaternary loess deposits in Europe
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atmospheric mineral dust is a fundamental component of the Earth’s climate system, with dust both responding to and driving climate change. This close link between dust and climate is recorded in archives of past dust activity, which show that abrupt 101-3 yr shifts in temperature during the last glacial period were accompanied with fluctuations in dust activity. However, the precise mechanism behind this close coupling of dust and climate and the specific role dust plays in modulating rapid climate change remains unclear. Terrestrial wind-blown dust deposits (loess) in Europe serve as source proximal archives of past dust activity. Loess formation chronologies across this region generally indicate greatly enhanced dust deposition during the last glacial cold phases of MIS 4 and, most notably, MIS 2. However, currently chronological precision is not sufficient to constrain more abrupt changes in dust activity and their potential links to climate change. More fundamentally, uncertainties over the sources of loess in Europe limit understanding of the causes of this last glacial dust deposition variability. The four chapters that comprise this thesis address these uncertainties through detailed analysis of the age and sources of loess in the Northern European Plain and English Channel region. Overall, the results demonstrate that abrupt changes in dust deposition during the late last glacial were a function of changes in ice sheet driven sediment supply. Eurasian and Alpine Ice Sheet derived meltwater pulses periodically greatly enhanced sediment availability and dust emission along their drainage routes, as reflected by abrupt dust deposition variability recorded in European loess deposits. Upon discharge into the North Atlantic, these meltwater pulses are also believed to have interacted with ocean circulation, potentially driving abrupt climate fluctuations during the last glacial. This provides a mechanism linking changes in dust, climate and ocean circulation on millennial timescales via ice sheet dynamics and provides the first coherent explanation of the close coupling of millennial scale variation in climate and dust during the Quaternary. Moreover, these findings suggest that meltwater pulses not only affected last glacial climate by changing ocean circulation but also through their impact on the high latitude dust cycle.
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| 4. |
- Beal, Samuel A., et al.
(författare)
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Ice Core Perspective on Mercury Pollution during the Past 600 Years
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:13, s. 7641-7647
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Tidskriftsartikel (refereegranskat)abstract
- Past emissions of the toxic metal mercury (Fig) persist in the global environment yet these emissions remain poorly constrained by existing data. Ice cores are high-resolution archives of atmospheric deposition that may provide crucial insight into past atmospheric Hg levels during recent and historical time. Here we present a record of total Hg (Hg-T) in an ice core from the pristine summit plateau (5340 m asl) of Mount Logan, Yukon, Canada, representing atmospheric deposition from AD 1410 to 1998. The Colonial Period (similar to 1603-1850) and North American "Gold Rush" (1850-1900) represent minor fractions (8% and 14%, respectively) of total anthropogenic Hg deposition in the record, with the majority (78%) occurring during the 20th Century. A period of maximum HgT fluxes from 1940 to 1975 coincides with estimates of enhanced anthropogenic Hg emissions from commercial sources, as well as with industrial emissions of other toxic metals. Rapid declines in HgT fluxes following peaks during the Gold Rush and the mid-20th Century indicate that atmospheric Hg deposition responds quickly to reductions in emissions. Increasing HgT fluxes from 1993 until the youngest samples in 1998 may reflect the resurgence of Hg emissions from unregulated coal burning and small-scale gold mining.
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| 5. |
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| 6. |
- Beaudoin, Anne, et al.
(författare)
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Palaeoenvironmental history of the last six centuries in the Nettilling Lake area (Baffin Island, Canada) : A multi-proxy analysis
- 2016
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Ingår i: The Holocene. - : Sage Publications. - 0959-6836 .- 1477-0911. ; 26:11, s. 1835-1846
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Tidskriftsartikel (refereegranskat)abstract
- The Baffin Island region in the eastern Canadian Arctic has recently experienced a rapid warming, possibly unprecedented in millennia. To investigate theresponse of freshwater environments to this warming and place it in a secular perspective, we analyzed a 90-cm-long sediment core from Nettilling Lake,the largest lake of the Canadian Arctic Archipelago. The core was taken from a part of the lake basin that receives meltwater and sediment inputs from thenearby Penny Ice Cap. The core time scale, established using 137Cs and palaeomagnetic techniques, spans an estimated 600 years. A multi-proxy approachwas used to document changes in the physical, chemical, and biological properties of the sediments. We found evidence for a relatively warm period (mid/late 15th century to mid/late 16th century) during the early part of the ‘Little Ice Age’ (LIA), characterized by high sedimentation rates and laminations.This was followed by colder, drier, and windier conditions corresponding to the coldest phase of LIA and coinciding with the latest and most extensiveperiod of regional ice cap expansion (early 16th to late 19th centuries). A rapid warming occurred at the beginning of the 20th century. Variations intitanium (Ti) content in the core, a proxy for detrital sediment inputs, showed good agreement with reconstructed secular variations in summer meltrates on Penny Ice Cap between the mid-14th century and the present-day, providing supporting evidence for a climatic–hydrological connection betweenthe ice cap and Nettilling Lake.
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| 7. |
- Beaudoin, Anne, et al.
(författare)
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Paleoenvironmental reconstructions of Nettilling Lake area (Baffin Island, Nunavut) : A multi-proxy analysis
- 2014
-
Konferensbidrag (refereegranskat)abstract
- The paleoclimate and paleolimnological history of several Arctic regions remains poorly known. This is the casefor the area around Nettilling Lake (Baffin Island, Nunavut), the largest lake of the Canadian Arctic Archipelago.To reconstruct the past environmental history of this area, a highly innovative multi-proxy approach combiningphysical, magnetic, chemical and biological properties preserved in lake sediments was used. One particular goalof this study was to investigate the possible coupling between sedimentation processes observed in the lake andmelt rates of nearby Penny Ice Cap.A 1-m long sediment core was retrieved from a small bay in the northeastern part of Nettilling Lake duringthe summer of 2010. This sampling area was chosen based on the hypothesis that incoming glacial meltwatersfrom Penny Ice Cap would leave a strong climate-modulated signal that would be reflected in the sedimentarysequence. The core was analyzed by both non-destructive (X-radiography (X-ray), microfluorescence-X (-XRF),magnetic susceptibility) and destructive (Loss On Ignition, grain size, water content, thin sections, diatoms)techniques. Radiometric AMS 14C and 210Pb/137Cs age determinations, as well as paleomagnetic measurements,were used to develop the core chronology, yielding an estimated bottom age of approximately 1365 AD.The sedimentation rate (0.15 cm.yr-1) in Nettilling Lake was found to be high compared to other Arctic lakes,due to inputs of highly turbid meltwaters from Penny Ice Cap with high suspended sediment loads. Significantcorrelations were found between geochemical profiles of elements linked to detrital inputs (Si, Ti, K, Ca) and meltrates from Penny Ice Cap since the 19th century. This suggests that variations in detrital elements in NettillingLake sediments might be used as an indirect indicator of regional climate fluctuations (e.g., summer temperatures) that determine glacier melt rates.
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| 8. |
- Campeau, Audrey, et al.
(författare)
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Controls on the 14C Content of Dissolved and Particulate Organic Carbon Mobilized Across the Mackenzie River Basin, Canada
- 2020
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Ingår i: Global Biogeochemical Cycles. - : AMER GEOPHYSICAL UNION. - 0886-6236 .- 1944-9224. ; 34:12
-
Tidskriftsartikel (refereegranskat)abstract
- The Mackenzie River Basin (MRB) delivers large quantities of organic carbon (OC) into the Arctic Ocean, with significant implications for the global C budgets and ocean biogeochemistry. The amount and properties of OC in the Mackenzie River's delta have been well monitored in the last decade, but the spatial variability in OC sources transported by its different tributaries is still unclear. Here we present new data on the radiocarbon (14C) content of dissolved and particulate OC (Δ14C‐DOC and Δ14C‐POC) across the mainstem and major tributaries of the MRB, comprising 19 different locations, to identify factors controlling spatial patterns in riverine OC sources. The Δ14C‐DOC and Δ14C‐POC varied across a large range, from −179.9‰ to 62.9‰, and −728.8‰ to −9.0‰, respectively. Our data reveal a positive spatial coupling between the Δ14C of DOC and POC across the MRB, whereby the most 14C‐depleted waters were issued from the mountainous west bank of the MRB. This 14C‐depleted DOC and POC likely originates from a combination of petrogenic sources, connected with the presence of kerogens in the bedrock, and biogenic sources, mobilized by thawing permafrost. Our analysis also reveals intriguing relationships between Δ14C of DOC and POC with turbidity, water stable isotope ratio and catchment elevation, indicating that hydrology and geomorphology are key to understanding riverine OC sources in this landscape. A closer examination of the specific mechanisms giving rise to these relationships is recommended. For now, this study provides a road map of the key OC sources in this rapidly changing river basin.
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| 9. |
- Campeau, Audrey, et al.
(författare)
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Sources of riverine mercury across the Mackenzie River Basin; inferences from a combined Hg C isotopes and optical properties approach
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 806, s. 150808-150808
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic terrestrial environment harbors a complex mosaic of mercury (Hg) and carbon (C) reservoirs, some of which are rapidly destabilizing in response to climate warming. The sources of riverine Hg across the Mackenzie River basin (MRB) are uncertain, which leads to a poor understanding of potential future release. Measurements of dissolved and particulate mercury (DHg, PHg) and carbon (DOC, POC) concentration were performed, along with analyses of Hg stable isotope ratios (incl. ∆199Hg, d202Hg), radiocarbon content (∆14C) and optical properties of DOC of river water. Isotopic ratios of Hg revealed a closer association to terrestrial Hg reservoirs for the particulate fraction, while the dissolved fraction was more closely associated with atmospheric deposition sources of shorter turnover time. There was a positive correlation between the ∆14C-OC and riverine Hg concentration for both particulate and dissolved fractions, indicating that waters transporting older-OC (14C-depleted) also contained higher levels of Hg. In the dissolved fraction, older DOC was also associated with higher molecular weight, aromaticity and humic content, which are likely associated with higher Hg-binding potential. Riverine PHg concentration increased with turbidity and SO4 concentration. There were large contrasts in Hg concentration and OC age and quality among the mountain and lowland sectors of the MRB, which likely reflect the spatial distribution of various terrestrial Hg and OC reservoirs, including weathering of sulfate minerals, erosion and extraction of coal deposits, thawing permafrost, forest fires, peatlands, and forests. Results revealed major differences in the sources of particulate and dissolved riverine Hg, but nonetheless a common positive association with older riverine OC. These findings reveal that a complex mixture of Hg sources, supplied across the MRB, will contribute to future trends in Hg export to the Arctic Ocean under rapid environmental changes.
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| 10. |
- Cardyn, R., et al.
(författare)
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Molar gas ratios of air entrapped in ice : A new tool to determine the origin of relict massive ground ice bodies in permafrost
- 2007
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 68:2, s. 239-248
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Tidskriftsartikel (refereegranskat)abstract
- The molar ratios of atmospheric gases change during dissolution in water due to differences in their relative solubilities. We exploited this characteristic to develop a tool to clarify the origin of ice formations in permafrost regions. Extracted from ice, molar gas ratios can distinguish buried glacier ice from intrasedimental ground ice formed by freezing groundwaters. An extraction line was built to isolate gases from ice by melting and trapping with liquid He, followed by analysis of N2, O2,, Ar, 18OO2 and 15NN2, by continuous flow mass spectrometry. The method was tested using glacier ice, aufeis ice (river icing) and intrasedimental ground ice from sites in the Canadian Arctic. O2/Ar and N2/Ar ratios clearly distinguish between atmospheric gas in glacial ice and gases from intrasedimental ground ice, which are exsolved from freezing water. δ15NN2 and δ18OO2 in glacier ice, aufeis ice and intrasedimental ground ice do not show clear distinguishing trends as they are affected by various physical processes during formation such as gravitational settling, excess air addition, mixing with snow pack, and respiration.
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| 11. |
- Copland, Luke, et al.
(författare)
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Surface Elevation Changes Over the Past Decade Across Penny Ice Cap, Baffin Island, Canada
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Geodetic methods have been relied on heavily to quantify the response of glaciers and ice caps to warmingover the past few decades (e.g. Abdalati et al., 2004; Gardner et al., 2011; Gardner et al., 2012). Typicallyin such studies, the observed surface elevation change of a glacier or ice cap over a given time interval is used to directly calculate its mass loss. However, there can be a change elevation due to a change in firndensification rate or ice dynamics without actual mass loss. For example, at the summit of Penny Ice Cap,Baffin Island, the firn density increased due to the formation of infiltration ice layers, resulting in a 6%increase in cumulative ice‐equivalent thickness between 1995 and 2010 (Zdanowicz et al., 2012).To our knowledge no studies have previously measured the vertical component of ice motion (firncompaction and/or ice dynamics) or adjusted geodetic data over an entire ice cap in the Canadian Arctic. Inthis study we use NASA Airborne Topographic Mapper (ATM) laser altimetry data, ICESat data, as well as insitu geodetic and surface mass balance measurements, to determine surface elevation changes over Penny Ice Cap from 2005‐2013, and correct these data to account for the effects of vertical motion due to ice dynamics and firn densification. Our results show that failure to account for vertical ice motion and firn densification would result in an~19% overestimation of mass loss for this ice cap.
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| 12. |
- Cosgrove, Christopher, et al.
(författare)
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Environmental controls on snow water equivalent in two sub-Arctic mountain catchments
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Spatial variability of seasonal snow depth poses a challenge when estimating snow water equivalent (SWE) from in-situ measurements in mountainous areas. Poor accessibility, complex topographic effects and localized microclimates make extrapolation of in-situ SWE measurements to a basin scale difficult. Remotely-sensed passive microwave SWE products are also inaccurate in complex terrain and/or at the forest-alpine tundra transition zone. To address these caveats, we investigated the relative importance of landscape qualities (altitude, slope, aspect, vegetation) and climate (winter temperatures, precipitation) on SWE distribution in two sub-Arctic mountainous catchments in Hemavan, Sweden, and Wolf Creek, Yukon, Canada. The two catchments are comparable, but have contrasted climate regimes. In-situ SWE measurements were made in March-April 2014 across the forest-tundra ecotone in both catchments. These were supplemented with historical snow-survey data since 2012 in Hemavan, and 1993 in Wolf Creek. Pairwise linear regressions of SWE against different landscape factors indicate that overall, altitude exerts the largest control on SWE at both Hemavan and Wolf Creek, but its effect is lesser within individual vegetation zones. In other respects, the two sites differ. SWE is inversely correlated to surface slope at forested sites in Hemavan (R^2 = 0.57, p = 0.25), but not in Wolf Creek. Slope aspect is positively correlated with SWE at forest-tundra transition sites (R^2 = 0.49, p = 0.12) in Wolf Creek, but not in Hemavan. For alpine tundra sites, slope angle strongly influences SWE in Hemavan (R^2 = 0.58, p = 0.24), but only weakly in Wolf Creek (R^2 = 0.05, p = 0.71). We discuss possible causes of these inter-catchment differences, and also evaluate the effect of inter-annual climate variations on SWE distribution at Wolf Creek using the long-term snow-survey record. Finally, we compare and discuss SWE estimates obtained by three different field measurement methods.
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| 13. |
- Dastoor, Ashu, et al.
(författare)
-
Arctic mercury cycling
- 2022
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Ingår i: Nature Reviews Earth & Environment. - : Springer Nature. - 2662-138X. ; 3:4, s. 270-286
-
Forskningsöversikt (refereegranskat)abstract
- Anthropogenic mercury (Hg) emissions have driven marked increases in Arctic Hg levels,which are now being impacted by regional warming, with uncertain ecological consequences. This Review presents a comprehensive assessment of the present-day total Hg mass balance in the Arctic. Over 98% of atmospheric Hg is emitted outside the region and is transported to the Arctic via long-range air and ocean transport. Around two thirds of this Hg is deposited in terrestrial ecosystems, where it predominantly accumulates in soils via vegetation uptake. Rivers and coastal erosion transfer about 80 Mg year−1 of terrestrial Hg to the Arctic Ocean, in approximate balance with modelled net terrestrial Hg deposition in the region. The revised Arctic Ocean Hg mass balance suggests net atmospheric Hg deposition to the ocean and that Hg burial in inner-shelf sediments is underestimated (up to >100%), needing seasonal observations of sediment-oceanHg exchange. Terrestrial Hg mobilization pathways from soils and the cryosphere (permafrost, ice, snow and glaciers) remain uncertain. Improved soil, snowpack and glacial Hg inventories, transfer mechanisms of riverine Hg releases under accelerated glacier and soil thaw, coupled atmosphere– terrestrial modelling and monitoring of Hg in sensitive ecosystems such as fjords can help toanticipate impacts on downstream Arctic ecosystems.
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| 14. |
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| 15. |
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| 16. |
- Eckhardt, Sabine, et al.
(författare)
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Revised historical Northern Hemisphere black carbon emissions based on inverse modeling of ice core records
- 2023
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Black carbon emitted by incomplete combustion of fossil fuels and biomasshas a net warming effect in the atmosphere and reduces the albedo whendeposited on ice and snow; accurate knowledge of past emissions is essentialto quantify and model associated global climate forcing. Although bottom-upinventories provide historical Black Carbon emission estimates that are widelyused in Earth System Models, they are poorly constrained by observationsprior to the late 20th century. Here we use an objective inversion techniquebased on detailed atmospheric transport and deposition modeling to reconstruct1850 to 2000 emissions from thirteen Northern Hemisphere ice-corerecords. We find substantial discrepancies between reconstructed Black Carbonemissions and existing bottom-up inventories which do not fully capturethe complex spatial-temporal emission patterns. Our findings imply changesto existing historical Black Carbon radiative forcing estimates are necessary,with potential implications for observation-constrained climate sensitivity.
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| 17. |
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| 18. |
- Fisher, D. A., et al.
(författare)
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The effects of flowline length evolution on chemistry - δ18O profiles from Penny Ice Cap, Baffin Island, Canada
- 2002
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Ingår i: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 35:1, s. 150-156
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Tidskriftsartikel (refereegranskat)abstract
- The isotopic and chemical signatures for ice-age and Holocene ice from Summit, Greenland, and Penny Ice Cap, Baffin Island, Canada, are compared. The usual pattern of low δ180, high Ca2+ and high Cl- is presented in the Summit records, but Penny Ice Cap has lower than present Cl- in its ice-age ice. A simple extension of the Hansson model (Hansson, 1994) is developed and used to simulate these signatures. The low ice age Cl- from Penny Ice Cap is explained by having the ice-age ice originating many thousands of km inland near the centre of the Laurentide ice sheet and much further from the marine sources. Summit's flowlines all start close to the present site. The Penny Ice Cap early-Holocene δ180's had to be corrected to offset the Laurentide meltwater distortion.The analysis suggests that presently the Summit and Penny Ice Cap marine impurity ori ginates about 500 km away, and that presently Penny Ice Cap receives a significant amountoflocal continental impurity.
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| 19. |
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| 20. |
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| 21. |
- Fisher, D., et al.
(författare)
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The Mt Logan Holocene-late Wisconsinan isotope record : Tropical Pacific-Yukon connections
- 2008
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Ingår i: Holocene. - : SAGE Publications. ; 18:5, s. 667-677
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Tidskriftsartikel (refereegranskat)abstract
- The ice core recovered from Prospector Russell Col on Mt Logan (5.4 km a.s.l.), in the Yukon spans over 20 000 years. This unique record offers a Pacific view of the stable isotope and chemical record from the Lateglacial to the present. The timescale is based on seasonal counted years, the largest known volcanic acid signatures and the major shift in stable isotopes and chemistry at the end of the Younger Dryas. There are large and sustained changes in the stable isotopic record that are anti-correlated with marine and continental chemistry series. The oxygen-18 in this area is not a proxy for palaeotemperature but rather for source region. The last major isotope shift in AD 1840 in δ(18O) and chemistry is compared with the Quinn's ENSO record. During periods of more frequent La Niña (stronger tropical easterlies) there is more zonal flow of water vapour transport to the Pacific Northwest, δ(18O) values are larger and the deuterium excess d smaller. These periods coincide with periods of lower accumulation/precipitation in southern Yukon. The Holocene δ(18O) record indicates many large shifts between the meridional (strong El Niño) and zonal (La Niña). Comparison of the Logan isotopic record and the moisture/temperature-sensitive time series of peat bog inception dates for the Northwest shows a strong correlation (0.36) that points to high accumulation rates coincident with low δ(18O) and enhanced meridional flow. Major changes in the core at 4200 BP and 7000—8000 BP point to enhanced meridional flow, which coincide with big changes in the Pacific palaeorecords of the balance between El Niño and La Niña. 4200 BP seems to have inaugurated the `modern' ENSO world.
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| 22. |
- Foy, N., et al.
(författare)
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Recent volume and area changes of Kaskawulsh Glacier, Yukon, Canada
- 2011
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Ingår i: Journal of Glaciology. - : International Glaciological Society. - 0022-1430 .- 1727-5652. ; 57:203, s. 515-525
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Tidskriftsartikel (refereegranskat)abstract
- Recent surface elevation changes of Kaskawulsh Glacier, Yukon, Canada, are quantified by comparing an air-photo derived DEM from 1977 and airborne lidar measurements from 1995, 2000 and 2007. Surface-area changes are assessed using historical aerial photography from 1956 and satellite imagery from 1977 to 2007. Combined, these measurements provide some of the first detailed records of volume change of a large Yukon glacier. Between 1977 and 2007, Kaskawulsh Glacier underwent a decrease in area of 1.53% and a decrease in volume of 3.27–5.94 km3 w.e.). The terminus also retreated by 655 m over the period 1956–2007. There was relatively minor volume change over the period 1977–95 (<+0.01 km3 w.e.a−1), while over the periods 1995–2000 and 2000–07 volume losses occurred at a relatively constant rate of −0.51 and −0.50 km3 a−1 w.e., respectively. Since 1995, thinning has been prominent throughout the ablation zone, while relative stability and even slight thickening has occurred in the accumulation zone. These findings are similar to those recently observed at other nearby Alaskan glaciers.
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| 23. |
- Gamberg, Mary, et al.
(författare)
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Mercury in the Canadian Arctic Terrestrial Environment : An Update
- 2015
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 509-510, s. 28-40
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Tidskriftsartikel (refereegranskat)abstract
- Contaminants in the Canadian Arctic have been studied over the last twenty years under the guidance of the Northern Contaminants Program. This paper provides the current state of knowledge on mercury (Hg) in theCanadian Arctic terrestrial environment. Snow, ice, and soils on land are key reservoirs for atmospheric deposition and can become sources of Hg through the melting of terrestrial ice and snow and via soil erosion. In the Canadian Arctic, new data have been collected for snow and ice that provide more information on the net accumulation and storage of Hg in the cryosphere. Concentrations of total Hg (THg) in terrestrial snow are highly variable but on average, relatively low (less than 5ng/L), and methylmercury (MeHg) levels in terrestrial snow are also generally low (less than 0.1 ng/L). On average, THg concentrations in snow on Canadian Arctic glaciers are muchlower than those reported on terrestrial lowlands or sea ice. Hg in snow may be affected by photochemical exchanges with the atmosphere mediated by marine aerosols and halogens, and by post-depositional redistribution within the snow pack. Regional accumulation rates of THg in Canadian Arctic glaciers varied little during the past century but show evidence of an increasing north-to-south gradient. Temporal trends of THg in glacier cores indicate an abrupt increase inthe early 1990s, possibly due to volcanic emissions, followed by more stable, but relatively elevated levels. Little information is available on Hg concentrations and processes in Arctic soils. Terrestrial Arctic wildlife typically have low levels of THg (less than μg/g dry weight) in their tissues, although caribou(Rangifer tarandus) can have higher Hg because they consume large amounts of lichen.THg concentrations in the Yukon’s Porcupine caribou herd vary among years but there has been no significant increase or decrease over the last two decades.
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| 24. |
- Keuschnig, Christoph, et al.
(författare)
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Selection processes of Arctic seasonal glacier snowpack bacterial communities
- 2023
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Ingår i: Microbiome. - : BioMed Central (BMC). - 2049-2618. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundArctic snowpack microbial communities are continually subject to dynamic chemical and microbial input from the atmosphere. As such, the factors that contribute to structuring their microbial communities are complex and have yet to be completely resolved. These snowpack communities can be used to evaluate whether they fit niche-based or neutral assembly theories.MethodsWe sampled snow from 22 glacier sites on 7 glaciers across Svalbard in April during the maximum snow accumulation period and prior to the melt period to evaluate the factors that drive snowpack metataxonomy. These snowpacks were seasonal, accumulating in early winter on bare ice and firn and completely melting out in autumn. Using a Bayesian fitting strategy to evaluate Hubbell’s Unified Neutral Theory of Biodiversity at multiple sites, we tested for neutrality and defined immigration rates at different taxonomic levels. Bacterial abundance and diversity were measured and the amount of potential ice-nucleating bacteria was calculated. The chemical composition (anions, cations, organic acids) and particulate impurity load (elemental and organic carbon) of the winter and spring snowpack were also characterized. We used these data in addition to geographical information to assess possible niche-based effects on snow microbial communities using multivariate and variable partitioning analysis.ResultsWhile certain taxonomic signals were found to fit the neutral assembly model, clear evidence of niche-based selection was observed at most sites. Inorganic chemistry was not linked directly to diversity, but helped to identify predominant colonization sources and predict microbial abundance, which was tightly linked to sea spray. Organic acids were the most significant predictors of microbial diversity. At low organic acid concentrations, the snow microbial structure represented the seeding community closely, and evolved away from it at higher organic acid concentrations, with concomitant increases in bacterial numbers.ConclusionsThese results indicate that environmental selection plays a significant role in structuring snow microbial communities and that future studies should focus on activity and growth.
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| 25. |
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| 26. |
- Kinnard, C., et al.
(författare)
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Calibration of an ice-core glaciochemical (sea-salt) record with sea-ice variability in the Canadian Arctic
- 2006
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Ingår i: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 44, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- Correlation between glaciochemical time Series from an ice core collected on Devon Ice Cap, Nunavut, Canada, and gridded time Series of Sea-ice concentrations reveals Statistically Significant inverse relationships between Sea-salt concentrations (mainly Na+, Mg2+ and Cl–) in the ice core and Sea-ice cover in Baffin Bay over the period 1980–97. An empirical orthogonal function (Eof) analysis performed on all major ions Shows that the dominant mode of glaciochemical variability (Eof1) represents a Sea-salt Signal, which correlates best with Sea-ice concentration in Baffin Bay. On a Seasonal basis, the Strongest and most Spatially extensive anticorrelations are found in Baffin Bay during the fall, followed by Spring, Summer and winter. These results Support the notion that increased open-water conditions in Baffin Bay during the Stormy Seasons (fall and Spring) promote increased production, transport and deposition of Sea-salt aerosols on Devon Ice Cap. Comparison of ice-core time Series of Eof1, δ18O and melt percentage, with air temperatures recorded in Upernavik, Greenland, Suggests that ice-cover variations in Baffin Bay over the past ∽145 years were dynamically rather than thermodynamically controlled, with periods of Strengthened cyclonic circulation leading to increased open-water conditions, and a greater Sea-salt flux on Devon Ice Cap.
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| 27. |
- Kinnard, C., et al.
(författare)
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Climatic analysis of sea-ice variability in the Canadian Arctic from operational charts, 1980-2004
- 2006
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Ingår i: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 44, s. 391-402
-
Tidskriftsartikel (refereegranskat)abstract
- We present a complete climatic analysis of Sea-ice conditions in the Canadian Arctic based on digitized operational charts from the Canadian Ice Service for the period 1980–2004. The Seasonal climatology, Spatial variance and linear trends in total ice concentrations (CT) were calculated. The maximum reduction rate in CT was found in the Beaufort Sea (>24% decade–1) and in the Davis Strait/Labrador Sea region (>18% decade–1) during Spring and Summer. Empirical orthogonal function (EOF) analysis performed on monthly CT deviations yielded four Significant EOF modes explaining 32% of the total variance. The Spatial pattern, temporal behaviour and Seasonality of these four EOF modes are discussed and correlated with fields of Sea-level pressure, Surface winds, Surface air temperature and Sea-surface temperature monthly anomalies. These results point to the dominant influence of the North Atlantic Oscillation on CT decadal anomalies during the cold Season, while climate variability in the Pacific influences CT variations in the Beaufort Sea region during Spring–summer.
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
- Lacelle, D., et al.
(författare)
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Nature and origin of a Pleistocene-age massive ground-ice body exposed in the Chapman Lake moraine complex, central Yukon Territory, Canada
- 2007
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 68:2, s. 249-260
-
Tidskriftsartikel (refereegranskat)abstract
- A massive ground-ice body was found exposed in the headwall of a thaw flow developed within the Chapman Lake terminal moraine complex on the Blackstone Plateau (Ogilvie Mountains, central Yukon Territory), which is contemporaneous to the Reid glaciation. Based on visible cryostructures in the 4-m-high headwall, two units were identified: massive ground ice, overlain sharply by 2 m of icy diamicton. The nature and origin of the Chapman Lake massive ground ice was determined using cryostratigraphy, petrography, stable O–H isotopes and the molar concentration of occluded gases (CO2, O2, N2 and Ar) entrapped in the ice, a new technique in the field of periglacial geomorphology that allows to distinguish between glacial and non-glacial intrasedimental ice. Collectively, the results indicate that the Chapman Lake massive ground ice formed by firn densification with limited melting–refreezing and underwent deformation near its margin. Given that the massive ground-ice body consists of relict glacier ice, it suggests that permafrost persisted, at least locally, on plateau areas in the central Yukon Territory since the middle Pleistocene. In addition, the d value of Chapman Lake relict glacier ice suggests that the ice covering the area during the Reid glaciation originated from a local alpine glaciation in the Ogilvie Mountains.
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| 33. |
- Løkkegaard, Anja, et al.
(författare)
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Greenland and Canadian Arctic ice temperature profiles database
- 2023
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Ingår i: The Cryosphere. - : Copernicus Publications. - 1994-0416 .- 1994-0424. ; 17:9, s. 3829-3845
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present a compilation of 95 ice temperature profiles from 85 boreholes from the Greenland ice sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Profiles from only 31 boreholes (36 %) were previously available in open-access data repositories. The remaining 54 borehole profiles (64 %) are being made digitally available here for the first time. These newly available profiles, which are associated with pre-2010 boreholes, have been submitted by community members or digitized from published graphics and/or data tables. All 95 profiles are now made available in both absolute (meters) and normalized (0 to 1 ice thickness) depth scales and are accompanied by extensive metadata. These metadata include a transparent description of data provenance. The ice temperature profiles span 70 years, with the earliest profile being from 1950 at Camp VI, West Greenland. To highlight the value of this database in evaluating ice flow simulations, we compare the ice temperature profiles from the Greenland ice sheet with an ice flow simulation by the Parallel Ice Sheet Model (PISM). We find a cold bias in modeled near-surface ice temperatures within the ablation area, a warm bias in modeled basal ice temperatures at inland cold-bedded sites, and an apparent underestimation of deformational heating in high-strain settings. These biases provide process level insight on simulated ice temperatures.
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| 34. |
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| 35. |
- Papasodoro, Charles, et al.
(författare)
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Area, elevation and mass changes of the two southernmost ice caps of the Canadian Arctic Archipelago between 1952 and 2014
- 2015
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Ingår i: The Cryosphere. - : European Geosciences Union (EGU). - 1994-0416 .- 1994-0424. ; 9, s. 1535-1550
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Tidskriftsartikel (refereegranskat)abstract
- Grinnell and Terra Nivea Ice Caps are located onthe southern Baffin Island, Nunavut, in the Canadian Arctic Archipelago. These relatively small ice caps have received little attention compared to the much larger ice masses further north. Their evolution can, however, give valuable information about the impact of the recent Arctic warming at lower latitudes (i.e. ∼62.5◦ N). In this paper, we measure or estimate historical and recent changes of area, elevation and mass of both ice caps using in situ, airborne and spaceborne data sets, including imagery from the Pléiades satellites. The area of Terra Nivea Ice Cap has decreased by 34 % since the late 1950s, while that of Grinnell Ice Cap has decreased by 20 % since 1952. For both ice caps, the areal reduction accelerated at the beginning of the 21st century. The estimated glacier-wide mass balance was−0.37 ± 0.21 m a^−1 water equivalent (w.e.) over Grinnell Ice Cap for the 1952–2014 period, and −0.47 ± 0.16 m a^−1 w.e. over Terra Nivea Ice Cap for the 1958/59–2014 period. Terra Nivea Ice Cap has experienced an accelerated rate of mass loss of −1.77 ± 0.36 m a^−1 w.e. between 2007 and 2014.This rate is 5.9 times as negative when compared to the 1958/59–2007 period (−0.30 ± 0.19 m a^−1 w.e.) and 2 times as negative when compared to the mass balance of other glaciers in the southern parts of Baffin Island over the 2003– 2009 period. A similar acceleration in mass loss is sus-pected for the Grinnell Ice Cap, given the calculated elevation changes and the proximity to Terra Nivea Ice Cap. The recent increase in mass loss rates for these two ice caps is linked to a strong near-surface regional warming and a lengthening of the melt season into the autumn that may beindirectly strengthened by a later freezing of sea ice in the Hudson Strait sector. On a methodological level, our study illustrates the strong potential of Pléiades satellite data to unlock the underexploited archive of old aerial photographs.
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| 36. |
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| 37. |
- Schaffer, Nicole, et al.
(författare)
-
Ice velocity changes on Penny Ice Cap, Baffin Island, since the 1950s
- 2017
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Ingår i: Journal of Glaciology. - : Cambridge University Press (CUP). - 0022-1430 .- 1727-5652. ; 63:240, s. 716-730
-
Tidskriftsartikel (refereegranskat)abstract
- Predicting the velocity response of glaciers to increased surface melt is a major topic of ongoing research with significant implications for accurate sea level rise forecasting. In this study we use optical and radar satellite imagery as well as comparisons with historical ground measurements to produce a multi-decadal record of ice velocity variations on Penny Ice Cap, Baffin Island. Over the period 1985 to 2011, the six largest outlet glaciers on the ice cap decelerated at an average rate of 21 m a-1 , or 12% per decade. The change was not monotonous, however, as most glaciers accelerated until the 1990s, then decelerated. A comparison of recent imagery with historical velocity measurements on Highway Glacier, on the southern part of Penny Ice Cap,shows that this glacier decelerated by 71% between 1953 and 2009/11, from 57 to 17 m a-1 . The recent slowdown of outlet glaciers has coincided with increases in mass loss, terminus retreat and an inferred reduction in basal sliding. Measured decelerations are greater than the total short term variability measured from both seasonal and interannual fluctuations, and supports the hypothesis that glacier thinning and/or increased meltwater production promotes a long-term reduction in ice motion.
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| 38. |
- Schaffer, Nicole, et al.
(författare)
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Modeling the surface mass balance of Penny Ice Cap, Baffin Island, 1959–2099
- 2023
-
Ingår i: Annals of Glaciology. - : Cambridge University Press. - 0260-3055 .- 1727-5644.
-
Tidskriftsartikel (refereegranskat)abstract
- Glaciers of Baffin Island and nearby islands of Arctic Canada have experienced rapid mass losses over recent decades. However, projections of loss rates into the 21st century have so far been limited by the availability of model calibration and validation data. In this study, we model the surface mass balance of the largest ice cap on Baffin Island, Penny Ice Cap, since 1959, using an enhanced temperature index model calibrated with in situ data from 2006–2014. Subsequently, we project changes to 2099 based on the RCP4.5 climate scenario. Since the mid-1990s, the surface mass balance over Penny Ice Cap has become increasingly negative, particularly after 2005. Using volume–area scaling to account for glacier retreat, peak net mass loss is projected to occur between ~2040 and 2080, and the ice cap is expected to lose 22% (377.4 Gt or 60 m w.e.) of its 2014 ice mass by 2099, contributing 1.0 mm to sea level rise. Our 2015–2099 projections are approximately nine times more sensitive to changes in temperature than precipitation, with an absolute cumulative difference of 566 Gt a–1 (90 m w.e.) between +2 and −2°C scenarios, and 63 Gt a–1 (10 m w.e.) between +20% and −20% precipitation scenarios.
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| 39. |
- Schaffer, Nicole, et al.
(författare)
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Revised estimates of recent mass loss rates for Penny Ice Cap, Baffin Island, based on 2005-2014 elevation changes modified for firn densification
- 2020
-
Ingår i: Journal of Geophysical Research - Earth Surface. - : American Geophysical Union (AGU). - 2169-9003 .- 2169-9011. ; 125:8
-
Tidskriftsartikel (refereegranskat)abstract
- Repeat airborne or satellite measurements of surface elevation over ice caps are often used tocalculate glacier‐wide surface mass changes over time. However, these measurements typically do notaccount for vertical ice motion caused by firn densification and/or ice flow, so the effect of these factors formass change measurements over an entire ice cap are currently poorly constrained. In this study, we updateNASA Airborne Topographic Mapper (ATM) altimetry elevation changes across Penny Ice Cap (BaffinIsland, Canada) to assess total changes in ice mass from 2005–2014, relative to 1995–2000. Dual‐frequencyGPS measurements and temporal changes in ice core density profiles are used to calculate firn densificationand ice flow to isolate the component of elevation change due to surface mass change. Envisat satelliteimagery is used to delineate the areas impacted by firn densification. These calculations, the first for aCanadian Arctic ice cap, indicate that accounting for firn densification may reduce the inferred surface massloss by ~13–15%. Overall, there has been a fourfold increase in mass loss from Penny Ice Cap between1995–2000 (−1.3 ± 0.7 Gt a−1) and 2005–2013 (−5.4 ± 1.9 Gt a−1). The rapid upglacier migration of theequilibrium line has left large areas of subsurface firn in the current ablation area and has far outpaced theice flow response, illustrating that the ice cap is not in equilibrium and out of balance with the currentclimate.
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| 40. |
- Schaffer, Nicole, et al.
(författare)
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Volume and mass changes over Penny Ice Cap, Baf-fin Island, from 2005-2013 determined from repeat air-borne laser altimetry.
- 2014
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Ingår i: Proceedings of the 2014 IASC Workshop on the dynamics and mass budget of Arctic glaciers.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Recent observations of accelerated glacier wastage in Greenland and Alaska haveprompted reassessments of mass balance trends and volume changes on Cana-dian Arctic glaciers and ice caps. While long surface mass balance measurementsare available from glaciers and ice caps in the Queen Elizabeth Islands (e.g., WhiteGlacier, Devon Ice Cap, Meighen Ice Cap), no such records exist for Baffin Islandglaciers. In the absence of such data, air- and space-borne measurements canbe used in combination with in situ data to evaluate historical and recent trendsin ice cover changes. Here, we use repeat laser airborne altimetry surveys con-ducted in 2005 and 2013 by NASA to estimate recent volume and mass changesof Penny Ice Cap, the southernmost large ice cap on Baffin Island ( 66N). Thesedata are validated against in-situ surface mass balance measurements from 2013and IceSat derived elevation change from 2003-2009. Once validated, surface el-evation changes along altimetry lines are extrapolated to the entire ice cap usinga digital elevation model (DEM). Changes in areal extent of the ice cap are con-strained using satellite imagery (e.g. Landsat). From these data we estimate thetotal mass wastage of the ice cap and its recent contribution to sea level rise. Thiswork builds on previous surveys for the period 1995-2005 (Abdalati et al.,2004;Gardneret al.,2012).
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| 41. |
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| 42. |
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| 43. |
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| 44. |
- Williamson, S.N., et al.
(författare)
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Evidence for elevation-dependent warming in the St. Elias Mountains, Yukon, Canada
- 2020
-
Ingår i: Journal of Climate. - : American Meteorological Society. - 0894-8755 .- 1520-0442. ; 33:8, s. 3253-3269
-
Tidskriftsartikel (refereegranskat)abstract
- The climate of high midlatitude mountains appears to be warming faster than the global average, butevidence for such elevation-dependent warming (EDW) at higher latitudes is presently scarce. Here, we use acomprehensive network of remote meteorological stations, proximal radiosonde measurements, downscaledtemperature reanalysis, ice cores, and climate indices to investigate the manifestation and possible drivers ofEDW in the St. Elias Mountains in subarctic Yukon, Canada. Linear trend analysis of comprehensivelyvalidated annual downscaled North American Regional Reanalysis (NARR) gridded surface air temperaturesfor the years 1979–2016 indicates a warming rate of 0.0288Ca21 between 5500 and 6000mabovemeansea level (MSL), which is ;1.6 times larger than the global-average warming rate between 1970 and 2015.The warming rate between 5500 and 6000m MSL was ;1.5 times greater than the rate at the 2000–2500mMSL bin (0.0198Ca21), which is similar to the majority of warming rates estimated worldwide over similarelevation gradients. Accelerated warming since 1979, measured by radiosondes, indicates a maximum rateat 400 hPa (;7010mMSL). EDWin the St. Elias region therefore appears to be driven by recent warmingof the free troposphere. MODIS satellite data show no evidence for an enhanced snow albedo feedbackabove 2500m MSL, and declining trends in sulfate aerosols deposited in high-elevation ice cores suggest amodest increase in radiative forcing at these elevations. In contrast, increasing trends in water vapor mixingratio at the 500-hPa level measured by radiosonde suggest that a longwave radiation vapor feedback iscontributing to EDW.
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| 45. |
- Yuan, Shengliu, et al.
(författare)
-
Insight into the Hg sources by stable isotopes of mercury in the largest Arctic river in North America
- 2020
-
Konferensbidrag (refereegranskat)abstract
- Mercury (Hg), especially in its methylated form (MeHg), is a global environmental toxicant with the threat to wildlife and humans. Although the Arctic is void of anthropogenic Hg emission,the elevated Hg content in the Arctic food web shows the significant impact of global Hg contamination. Besides the atmospheric input, the Arctic rivers may also deliver a large amount of Hg, 44 ± 4 Mg per year (1σ) by observations and extrapolation, intothe Arctic Ocean. However, the contributions of different sources to riverine discharge remain mostly unknown. This makes it challenging to reduce the anthropogenic Hg emission in the future, since this is messed by the natural Hg, including the precipitation Hg and the released Hg of permafrost thaw in response to the global warming. To anticipate the risk of Hg contamination in Arctic ecosystems, it is vital to identify the sources in the Arctic riverine. Here,we collected and analyzed the set of river samples in Mackenzie River, the largest Arctic river in North America. The Hg concentrations and isotopic compositions show the spatial and temporal distribution, with the higher concentrations the particle Hg than dissolved Hg and the higher concentrations in downstream than upstream. Notably, the significant difference of Hg isotopic compositions between the particle and dissolved Hg, coupling with the carbon isotopes, shows that the atmospheric precipitation Hg is the primary source of the dissolved phase, higher proportion Hg of permafrost Hg contributes to the particulate Hg. This constraint of the Hg sources will be conducive to evaluate the future risk to Arctic aquatic ecosystems under the background of global climate warming.
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| 46. |
- Zdanowicz, Christian, 1966-, et al.
(författare)
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An agenda for the future of Arctic snow research : the view from Svalbard
- 2024
-
Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 42
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic region is warming at over twice the mean rate of the Northern Hemisphere and nearly four times faster than the globe since 1979. The local rate of warming is even higher in the European archipelago of Svalbard. This warming is transforming the terrestrial snow cover, which modulates surface energy exchanges with the atmosphere, accounts for most of the runoff in Arctic catchments and is also a transient reservoir of atmospherically deposited compounds, including pollutants. Improved observations, understanding and modelling of changes in Arctic snow cover are needed to anticipate the effects these changes will have on the Arctic climate, atmosphere, terrestrial ecosystems and socioeconomic factors. Svalbard has been an international hub of polar research for many decades and benefits from a well-developed science infrastructure. Here, we present an agenda for the future of snow research in Svalbard, jointly developed by a multidisciplinary community of experts. We review recent trends in snow research, identify key knowledge gaps, prioritize future research efforts and recommend supportive actions to advance our knowledge of present and future snow conditions pertaining to glacier mass balance, permafrost, surface hydrology, terrestrial ecology, the cycling and fate of atmospheric contaminants, and remote sensing of snow cover. This perspective piece addresses issues relevant to the circumpolar North and could be used as a template for other national or international Arctic research plans.
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| 47. |
- Zdanowicz, Christian, et al.
(författare)
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Basal debris entrainment and transport in glaciers of southwestern Bylot Island, Canadian Arctic
- 1996
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Ingår i: Annals of Glaciology. - 0260-3055 .- 1727-5644. ; 22:1, s. 107-113
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT. Glaciers on southwestern Bylot Island in the Canadian Arctic flow from an alpine setting in high-grade crystalline Archean terrane, on to coastal lowlands underlain by clastic sedimentary strata of Cretaceous to Tertiary age. We have used the contrasting mineralogy of the substrate as a tool to study subglacialentrainment and transport of debris in two large piedmont glaciers on Bylot Island. High chlorite/ and mica-illite/smectite ratios indicate that most basal debris is derived from crystalline rocks underlying the upper reaches of the glaciers. The subglacial accretion of Cretaceous-Tertiary sediments appears restricted to the lowermost part ofthe basal zone and is most noticeable near the glaciers' termini. lce associated with discrete silty-sandy debris layers is characterized by an isotopic signature indicative of refreezing of meltwater at the glacier sole. The compositional, textural and isotopic characteristics of basal sediment and ice lead us to conclude that subglacial entrainment through basal ice accretion occurs in both the upper and marginal parts of the glaciers
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| 48. |
- Zdanowicz, Christian, 1966-, et al.
(författare)
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Elemental and water-insoluble organic carbon in Svalbard snow: a synthesis of observations during 2007-2018
- 2021
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:4, s. 3035-3057
-
Tidskriftsartikel (refereegranskat)abstract
- Light-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplifying Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their distribution in snow is needed to assess their impact. Here we present and synthesize new data obtained on Svalbard between 2007 and 2018, comprising measurements of elemental (EC) and water-insoluble organic carbon (WIOC) in snow from 37 separate sites. We used these data, combined with meteorological data and snowpack modeling, to investigate the variability of EC and WIOC deposition in Svalbard snow across latitude, longitude, elevation and time. Overall, EC concentrations (C-snow(EC)) ranged from < 1.0 to 266.6 ng g(-1), while WIOC concentrations (C-snow(WIOC)) ranged from < 1 to 9426 ng g(-1), with the highest values observed near Ny-Alesund. Calculated snowpack loadings (L-snow(EC), L-snow(WIOC)) on glaciers surveyed in spring 2016 were 0.1 to 2.6 mg m(-2) and 2 to 173 mg m(-2), respectively. The median C-snow(EC) and the L-snow(EC) on those glaciers were close to or lower than those found in earlier (2007- 2009), comparable surveys. Both L-snow(EC) and L(snow)(WIOC )increased with elevation and snow accumulation, with dry deposition likely playing a minor role. Estimated area-averaged snowpack loads across Svalbard were 1.1 mg EC m(-2) and 38.3 mg WIOC m(-2) for the 2015-2016 winter. An similar to 11-year long dataset of spring surface snow measurements from the central BrOgger Peninsula was used to quantify the interannual variability of EC and WIOC deposition in snow. In most years, C-snow(EC) and C-snow(WIOC) at Ny-Alesund (50 m a.s.l.) were 2-5 times higher than on the nearby Austre Brogger-breen glacier (456 m a.s.l.), and the median EC/WIOC in Ny-Alesund was 6 times higher, suggesting a possible influence of local EC emission from Ny-Alesund. While no long-term trends between 2011 and 2018 were found, C-snow(EC) and C-snow(WIOC) showed synchronous variations at Ny-Alesund and Austre Broggerbreen. When compared with data from other circum-Arctic sites obtained by comparable methods, the median C(snow)(EC)on Svalbard falls between that found in central Greenland (lowest) and those in continental sectors of European Arctic (northern Scandinavia, Russia and Siberia; highest), which is consistent with large-scale patterns of BC in snow reported by surveys based on other methods.
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| 49. |
- Zdanowicz, Christian, 1966-, et al.
(författare)
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Historical black carbon deposition in the Canadian High Arctic : A >250-year long ice-core record from Devon Island
- 2018
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus Publications. - 1680-7316 .- 1680-7324. ; 18, s. 12345-12361
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Tidskriftsartikel (refereegranskat)abstract
- Black carbon aerosol (BC) emitted from natural and anthropogenic sources (e.g., wildfires, coal burning) can contribute to magnify climate warming at high latitudes by darkening snow- and ice-covered surfaces, thus lowering their albedo. Modeling the atmospheric transport and deposition of BC to the Arctic is therefore important, and historical archives of BC accumulation in polar ice can help to validate such modeling efforts. Here we present a 190-year ice-core record of refractory BC (rBC) deposition on Devon ice cap, Canada, spanning calendar years 1810-1990, the first such record ever developed from the Canadian Arctic. The estimated mean deposition flux of rBC on Devon ice cap for 1963-1990 is 0.2 mg m-2 a-1, which is low compared to most Greenland ice-core sites over the same period. The Devon ice cap rBC record also differs from existing Greenland records in that it shows no evidence of a substantial increase in rBC deposition during the early-mid 20th century, which, for Greenland, has been attributed to mid-latitude coal burning emissions. The deposition of other contaminants such as sulfate and Pb increased on Devon ice cap in the 20th century but without a concomitant rise in rBC. Part of the difference with Greenland may be due to local factors such as wind scouring of winter snow at the coring site on Devon ice cap. Air back-trajectory analyses also suggest that Devon ice cap receives BC from more distant North American and Eurasian sources than Greenland, and aerosol mixing and removal during long-range transport over the Arctic Ocean likely masks some of the specific BC source-receptor relationships. Findings from this study underscore the large variability in BC aerosol deposition across the Arctic region that may arise from different transport patterns. This variability needs to be accounted for when estimating the large-scale albedo lowering effect of BC deposition on Arctic snow/ice.
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| 50. |
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