Slope thermokarst transforms permafrost preserved glacial landscapes and effects propagate through Arctic drainage networks.

2020 ◽  
Author(s):  
Steve Kokelj ◽  
Justin Kokoszka ◽  
Jurjen van der Sluijs ◽  
Ashley Rudy ◽  
Jon Tunnicliffe ◽  
...  
Keyword(s):  
Drainage Basin ◽  
The Arctic ◽  
Arctic Canada ◽  
Stream Length ◽  
Sediment Delivery ◽  
Glacial Sediments ◽  
Downstream Effects ◽  
Drainage Networks ◽  
Western Arctic ◽  
Systems Mapping

<p>Recent intensification of slope thermokarst is transforming permafrost preserved glaciated landscapes and causing significant downstream effects. In this paper we: A) Describe the thaw-related mechanisms driving the evolution of slope to stream connectivity; B) define the watershed patterns of thermokarst intensification; and C) project the cascade of effects through the Arctic drainage networks of northwestern Canada. The power-law relationships between disturbance area and volume, and thickness of permafrost thawed, in conjunction with a time-series of disturbance mapping show that the non-linear intensification of slope thermokarst is mobilizing vast stores of previously frozen glacial sediments linking slopes to downstream systems. Mapping across a range of catchment scales indicates that slope thermokarst predominantly affects first and second order streams. Slope sediment delivery now frequently exceeds fluvial transport capacity of these streams by several orders of magnitude indicating long-term perturbation. Mapping shows slope thermokarst is directly affecting over 6760 km of stream segments, over 890 km of coastline and over 1370 lakes across the 1,000,000 km<sup>2</sup> Arctic drainage basin from continuous permafrost of northwestern Canada. The downstream projection of thermokarst disturbance increases affected lakes by a factor of 4 and stream length by a factor of 7, and suggests that fluvial transfer has the potential to yield numerous thermokarst impact zones across coastal areas of western Arctic Canada. The Prince of Wales Strait between Banks and Victoria Islands is identified as a hotspot of downstream thermokarst effects, and the Peel and Mackenzie rivers stand out as principle conveyors of slope thermokarst effects to North America’s largest Delta and to the Beaufort Sea.<strong> </strong>The distribution of slope thermokarst and the fluvial pattern of sediment mobilization signal the climate-driven rejuvenation of post-glacial landscape change and the triggering of a time-transient cascade of downstream effects. Geological legacy and the patterns of continental drainage dictate that terrestrial, freshwater and marine environments of western Arctic Canada will be a hotspot of climate-driven change through the coming centuries. </p>

scholarly journals Permafrost thaw couples slopes with downstream systems and effects propagate through Arctic drainage networks

2020 ◽  
Author(s):  
Steven V. Kokelj ◽  
Justin Kokoszka ◽  
Jurjen van der Sluijs ◽  
Ashley C. A. Rudy ◽  
John Tunnicliffe ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Mass Wasting ◽  
Catchment Scale ◽  
Stream Length ◽  
Sediment Delivery ◽  
Downstream Effects ◽  
Drainage Networks ◽  
Order Of Magnitude ◽  
Climate Controls ◽  
Stream Transport

Abstract. The intensification of thaw-driven mass wasting is transforming glacially-conditioned permafrost terrain, coupling slopes with aquatic systems, and triggering a cascade of downstream effects. Within the context of recent, rapidly evolving climate controls on the geomorphology of permafrost terrain we: A) quantify three-dimensional slump enlargement and described the processes and thresholds coupling slopes to downstream systems; B) investigate catchment-scale patterns of slope thermokarst (thaw slumps and slides) impacts and the geomorphic implications; and C) project the propagation of effects through hydrological networks draining continuous permafrost of northwestern Canada. Power-law relationships between thaw-slump area and volume (R2 = 0.90), and thickness of permafrost thawed (R2 = 0.63), combined with the multi-decadal (1985–2018) increase in areal extent of thaw-slump disturbance show a two-order of magnitude increase in catchment-scale geomorphic activity and the coupling of slope and hydrological systems. Predominant catchment effects are to first- and second-order streams where sediment delivery commonly exceeds stream transport capacity by orders of magnitude indicating millennial-scale perturbation of downstream systems. Assessment of hydrological networks indicates thaw-driven mass wasting directly affects over 6,760 km of stream segments, 890 km of coastline, and 1,370 lakes in the 994,860 km2 study area. Downstream propagation of slope thermokarst indicates a potential increase in the number of affected lakes by at least a factor of 4 (n > 5,600), impacted stream length by a factor of 7 (> 48,000 km) and defines several major impact zones to lakes, deltas, and coastal areas. Prince of Wales Strait is the receiving marine environment for greatly increased sediment and geochemical fluxes from numerous slump impacted hydrological networks draining the landmasses of Banks and Victoria Islands. Peel and Mackenzie Rivers are globally significant conveyors of the slope thermokarst cascade delivering effects to North America’s largest Delta and the Beaufort Sea. Climate-driven erosion of ice-rich slopes in permafrost preserved glaciated terrain has triggered a time-transient cascade of downstream effects that signal the renewal of post-glacial landscape evolution. Glacial legacy and the patterns of continental drainage dictate that terrestrial, freshwater and marine environments of western Arctic Canada will be an interconnected hotspot of thaw-driven change through the coming millennia.

Expansion of the Trade in Northern Alaska and Western Arctic Canada

2018 ◽  
Author(s):  
John R. Bockstoce
Keyword(s):  
San Francisco ◽  
Fur Trade ◽  
The Arctic ◽  
Arctic Canada ◽  
Trading Company ◽  
Whaling Industry ◽  
Western Arctic ◽  
Northern Alaska

This chapter focuses on the development and advance of the arctic fur trade to the year 1914: the decline of the shore whaling industry and the rise of the market for white fox furs; the beginning of the dispersal of trapping families along the coast; the importance of the Cape Smythe Whaling and Trading Company at Barrow, Alaska; and the activities of H. Liebes and Company, furriers of San Francisco.

scholarly journals Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history

2017 ◽  
Vol 13 (5) ◽  
pp. 511-531 ◽  
Author(s):  
Linsen Dong ◽  
Yanguang Liu ◽  
Xuefa Shi ◽  
Leonid Polyak ◽  
Yuanhui Huang ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Ice Sheet ◽  
Mineralogical Composition ◽  
Detailed Examination ◽  
Canada Basin ◽  
The Arctic ◽  
Middle Pleistocene ◽  
Sediment Delivery ◽  
Sea Levels ◽  
Western Arctic

Abstract. Sediment core ARC4-BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stage – MIS – 1–15, ca. 0.5–0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7–8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.

scholarly journals Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history

2017 ◽  
Author(s):  
Linsen Dong ◽  
Yanguang Liu ◽  
Xuefa Shi ◽  
Leonid Polyak ◽  
Yuanhui Huang ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Ice Sheet ◽  
Mineralogical Composition ◽  
Detailed Examination ◽  
Canada Basin ◽  
The Arctic ◽  
Middle Pleistocene ◽  
14C Dating ◽  
Sediment Delivery ◽  
Western Arctic

Abstract. Sediment core ARC4–BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stages (MIS) 1–15, ca. 0.5–0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS 14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktonic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7/8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.

scholarly journals Thaw-driven mass wasting couples slopes with downstream systems, and effects propagate through Arctic drainage networks

2021 ◽  
Vol 15 (7) ◽  
pp. 3059-3081
Author(s):  
Steven V. Kokelj ◽  
Justin Kokoszka ◽  
Jurjen van der Sluijs ◽  
Ashley C. A. Rudy ◽  
Jon Tunnicliffe ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Mass Wasting ◽  
Catchment Scale ◽  
Stream Length ◽  
Sediment Delivery ◽  
Drainage Patterns ◽  
Downstream Effects ◽  
Order Of Magnitude ◽  
Retrogressive Thaw Slump ◽  
Victoria Island

Abstract. The intensification of thaw-driven mass wasting is transforming glacially conditioned permafrost terrain, coupling slopes with aquatic systems, and triggering a cascade of downstream effects. Within the context of recent, rapidly evolving climate controls on the geomorphology of permafrost terrain, we (A) quantify three-dimensional retrogressive thaw slump enlargement and describe the processes and thresholds coupling slopes to downstream systems, (B) investigate catchment-scale patterns of slope thermokarst impacts and the geomorphic implications, and (C) map the propagation of effects through hydrological networks draining permafrost terrain of northwestern Canada. Power-law relationships between retrogressive thaw slump area and volume (R2=0.90), as well as the thickness of permafrost thawed (R2=0.63), combined with the multi-decadal (1986–2018) increase in the areal extent of thaw slump disturbance, show a 2 order of magnitude increase in catchment-scale geomorphic activity and the coupling of slope and hydrological systems. Predominant effects are to first- and second-order streams where sediment delivery, often indicated by formation of recent debris tongue deposits, commonly exceeds the transport capacity of headwater streams by orders of magnitude, signaling centennial- to millennial-scale perturbation of downstream systems. Assessment of hydrological networks indicates that thaw-driven mass wasting directly affects over 5538 km of stream segments, 889 km of coastline, and 1379 lakes in the 994 860 km2 study area. Downstream propagation of slope thermokarst indicates a potential increase in the number of affected lakes by at least a factor of 4 (n>5692) and impacted stream length by a factor of 8 (>44 343 km), and it defines several major impact zones on lakes, deltas, and coastal areas. Prince of Wales Strait is the receiving marine environment for greatly increased sediment and geochemical fluxes from numerous slump-impacted hydrological networks draining Banks Island and Victoria Island. The Peel and Mackenzie rivers are globally significant conveyors of the slope thermokarst cascade, delivering effects to North America's largest Arctic delta and the Beaufort Sea. Climate-driven erosion of ice-rich slopes in permafrost-preserved glaciated terrain has triggered a time-transient cascade of downstream effects that signal the rejuvenation of post-glacial landscape evolution. Glacial legacy, ground-ice conditions, and continental drainage patterns dictate that terrestrial, freshwater, coastal, and marine environments of western Arctic Canada will be an interconnected hotspot of thaw-driven change through the coming millennia.

scholarly journals N2O dynamics in the western Arctic Ocean during the summer of 2017

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jang-Mu Heo ◽  
Seong-Su Kim ◽  
Sung-Ho Kang ◽  
Eun Jin Yang ◽  
Ki-Tae Park ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Environmental Changes ◽  
Chukchi Sea ◽  
Hot Spot ◽  
Open Water ◽  
Northern Region ◽  
The Arctic ◽  
Western Arctic Ocean ◽  
Deep Layers ◽  
Western Arctic

AbstractThe western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N2O) cycles from greenhouse gases. We investigated WAO N2O dynamics through an intensive and precise N2O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N2O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N2O production (i.e., through nitrification), with N2O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N2O (mean: + 2.3 ± 2.7 μmol N2O m−2 day−1), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N2O m−2 day−1). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N2O “hot spot”, and therefore, a key region requiring continued observations to both understand N2O dynamics and possibly predict their future changes.

scholarly journals Arctic Ocean stratification set by sea level and freshwater inputs since the last ice age

2021 ◽  
Author(s):  
Jesse R. Farmer ◽  
Daniel M. Sigman ◽  
Julie Granger ◽  
Ona M. Underwood ◽  
François Fripiat ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Surface Waters ◽  
Ice Age ◽  
The Arctic ◽  
Bering Strait ◽  
Central Arctic Ocean ◽  
Phytoplankton Productivity ◽  
Nitrate Consumption ◽  
Western Arctic ◽  
Last Ice Age

AbstractSalinity-driven density stratification of the upper Arctic Ocean isolates sea-ice cover and cold, nutrient-poor surface waters from underlying warmer, nutrient-rich waters. Recently, stratification has strengthened in the western Arctic but has weakened in the eastern Arctic; it is unknown if these trends will continue. Here we present foraminifera-bound nitrogen isotopes from Arctic Ocean sediments since 35,000 years ago to reconstruct past changes in nutrient sources and the degree of nutrient consumption in surface waters, the latter reflecting stratification. During the last ice age and early deglaciation, the Arctic was dominated by Atlantic-sourced nitrate and incomplete nitrate consumption, indicating weaker stratification. Starting at 11,000 years ago in the western Arctic, there is a clear isotopic signal of Pacific-sourced nitrate and complete nitrate consumption associated with the flooding of the Bering Strait. These changes reveal that the strong stratification of the western Arctic relies on low-salinity inflow through the Bering Strait. In the central Arctic, nitrate consumption was complete during the early Holocene, then declined after 5,000 years ago as summer insolation decreased. This sequence suggests that precipitation and riverine freshwater fluxes control the stratification of the central Arctic Ocean. Based on these findings, ongoing warming will cause strong stratification to expand into the central Arctic, slowing the nutrient supply to surface waters and thus limiting future phytoplankton productivity.

scholarly journals Arctic riparian shrub expansion indicates a shift from streams gaining water to those that lose flow

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Anna K. Liljedahl ◽  
Ina Timling ◽  
Gerald V. Frost ◽  
Ronald P. Daanen
Keyword(s):  
Microbial Communities ◽  
Soil Microbial Communities ◽  
Late Summer ◽  
Field Measurements ◽  
The Arctic ◽  
Shrub Expansion ◽  
Riparian Ecosystems ◽  
Stream Length ◽  
Area Index ◽  
Soil Microbial

AbstractShrub expansion has been observed across the Arctic in recent decades along with warming air temperatures, but tundra shrub expansion has been most pronounced in protected landscape positions such as floodplains, streambanks, water tracks, and gullies. Here we show through field measurements and laboratory analyses how stream hydrology, permafrost, and soil microbial communities differed between streams in late summer with and without tall shrubs. Our goal was to assess the causes and consequences of tall shrub expansion in Arctic riparian ecosystems. Our results from Toolik Alaska, show greater canopy height and density, and distinctive plant and soil microbial communities along stream sections that lose water into unfrozen ground (talik) compared to gaining sections underlain by shallow permafrost. Leaf Area Index is linearly related to the change in streamflow per unit stream length, with the densest canopies coinciding with increasingly losing stream sections. Considering climate change and the circumpolar scale of riparian shrub expansion, we suggest that permafrost thaw and the resulting talik formation and shift in streamflow regime are occurring across the Low Arctic.

scholarly journals Stable-isotope time series and precipitation origin from firn-core and snow samples, Altai glaciers, Siberia

2005 ◽  
Vol 51 (175) ◽  
pp. 637-654 ◽  
Author(s):  
Vladimir B. Aizen ◽  
Elena Aizen ◽  
Koji Fujita ◽  
Stanislav A. Nikitin ◽  
Karl J. Kreutz ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Clustering Analysis ◽  
Meteoric Water ◽  
Drainage Basin ◽  
The Arctic ◽  
Deuterium Excess ◽  
Closed Drainage ◽  
Water Stable Isotope ◽  
Firn Core ◽  
Snow Samples

AbstractIn the summers of 2001 and 2002, glacio-climatological research was performed at 4110–4120 m a.s.l. on the Belukha snow/firn plateau, Siberian Altai. Hundreds of samples from snow pits and a 21 m snow/firn core were collected to establish the annual/seasonal/monthly depth–accumulation scale, based on stable-isotope records, stratigraphic analyses and meteorological and synoptic data. The fluctuations of water stable-isotope records show well-preserved seasonal variations. The δ18O and δD relationships in precipitation, snow pits and the snow/firn core have the same slope to the covariance as that of the global meteoric water line. The origins of precipitation nourishing the Belukha plateau were determined based on clustering analysis of δ18O and d-excess records and examination of synoptic atmospheric patterns. Calibration and validation of the developed clusters occurred at event and monthly timescales with about 15% uncertainty. Two distinct moisture sources were shown: oceanic sources with d-excess <12‰, and the Aral–Caspian closed drainage basin sources with d-excess >12‰. Two-thirds of the annual accumulation was from oceanic precipitation, of which more than half had isotopic ratios corresponding to moisture evaporated over the Atlantic Ocean. Precipitation from the Arctic/Pacific Ocean had the lowest deuterium excess, contributing one-tenth to annual accumulation.

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