@article{IrrgangLantuitMansonetal.2018, author = {Irrgang, Anna Maria and Lantuit, Hugues and Manson, Gavin K. and G{\"u}nther, Frank and Grosse, Guido and Overduin, Pier Paul}, title = {Variability in rates of coastal change along the Yukon Coast, 1951 to 2015}, series = {Journal of geophysical research : Earth surface}, volume = {123}, journal = {Journal of geophysical research : Earth surface}, number = {4}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9003}, doi = {10.1002/2017JF004326}, pages = {779 -- 800}, year = {2018}, abstract = {To better understand the reaction of Arctic coasts to increasing environmental pressure, coastal changes along a 210-km length of the Yukon Territory coast in north-west Canada were investigated. Shoreline positions were acquired from aerial and satellite images between 1951 and 2011. Shoreline change rates were calculated for multiple time periods along the entire coast and at six key sites. Additionally, Differential Global Positioning System (DGPS) measurements of shoreline positions from seven field sites were used to analyze coastal dynamics from 1991 to 2015 at higher spatial resolution. The whole coast has a consistent, spatially averaged mean rate of shoreline change of 0.7 +/- 0.2 m/a with a general trend of decreasing erosion from west to east. Additional data from six key sites shows that the mean shoreline change rate decreased from -1.3 +/- 0.8 (1950s-1970s) to -0.5 +/- 0.6 m/a (1970s-1990s). This was followed by a significant increase in shoreline change to -1.3 +/- 0.3 m/a in the 1990s to 2011. This increase is confirmed by DGPS measurements that indicate increased erosion rates at local rates up to -8.9 m/a since 2006. Ground surveys and observations with remote sensing data indicate that the current rate of shoreline retreat along some parts of the Yukon coast is higher than at any time before in the 64-year-long observation record. Enhanced availability of material in turn might favor the buildup of gravel features, which have been growing in extent throughout the last six decades. Plain Language Summary The Arctic is warming, but the impacts on its coasts are not well documented. To better understand the reaction of Arctic coasts to increasing environmental pressure, shoreline position changes along a 210-km length of the Yukon Territory coast in northwest Canada were investigated for the time period from 1951 to 2015. Shoreline positions were extracted from historical aerial images from the 1950s, 1970s, and 1990s and from satellite images from 2011. Additionally, measurements of shoreline positions from field sites were used to analyze coastal dynamics from 1991 to 2015. The mean shoreline change rate was -1.3 m/a between the 1950s and 1970s and followed by a decrease to -0.5 m/a between the 1970s to 1990s. This was followed by a significant increase in mean shoreline change rates again to -1.3 m/a in the 1990s to 2011 time period. This acceleration in erosion is confirmed by field measurements that indicate increased erosion rates at high local rates up to -8.9 m/a since 2006. Enhanced coastal erosion might, in turn, favor the buildup of gravel features, which have been growing in extent throughout the last six decades.}, language = {en} } @article{WolterLantuitHerzschuhetal.2017, author = {Wolter, Juliane and Lantuit, Hugues and Herzschuh, Ulrike and Stettner, Samuel and Fritz, Michael}, title = {Tundra vegetation stability versus lake-basin variability on the Yukon Coastal Plain (NW Canada) during the past three centuries}, series = {The Holocene : an interdisciplinary journal focusing on recent environmental change}, volume = {27}, journal = {The Holocene : an interdisciplinary journal focusing on recent environmental change}, publisher = {Sage Publ.}, address = {London}, issn = {0959-6836}, doi = {10.1177/0959683617708441}, pages = {1846 -- 1858}, year = {2017}, language = {en} } @article{TanskiLantuitRuttoretal.2017, author = {Tanski, George and Lantuit, Hugues and Ruttor, Saskia and Knoblauch, Christian and Radosavljevic, Boris and Strauß, Jens and Wolter, Juliane and Irrgang, Anna Maria and Ramage, Justine Lucille and Fritz, Michael}, title = {Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {581}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier Science}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2016.12.152}, pages = {434 -- 447}, year = {2017}, abstract = {The changing climate in the Arctic has a profound impact on permafrost coasts, which are subject to intensified thermokarst formation and erosion. Consequently, terrestrial organic matter (OM) is mobilized and transported into the nearshore zone. Yet, little is known about the fate of mobilized OM before and after entering the ocean. In this study we investigated a retrogressive thaw slump (RTS) on Qikiqtaruk - Herschel Island (Yukon coast, Canada). The RTS was classified into an undisturbed, a disturbed (thermokarst-affected) and a nearshore zone and sampled systematically along transects. Samples were analyzed for total and dissolved organic carbon and nitrogen (TOC, DOC, TN, DN), stable carbon isotopes (delta C-13-TOC, delta C-13-DOC), and dissolved inorganic nitrogen (DIN), which were compared between the zones. C/N-ratios, delta C-13 signatures, and ammonium (NH4-N) concentrations were used as indicators for OM degradation along with biomarkers (n-alkanes, n-fatty adds, n-alcohols). Our results show that OM significantly decreases after disturbance with a TOC and DOC loss of 77 and 55\% and a TN and DN loss of 53 and 48\%, respectively. C/N-ratios decrease significantly, whereas NH4-N concentrations slightly increase in freshly thawed material. In the nearshore zone, OM contents are comparable to the disturbed zone. We suggest that the strong decrease in OM is caused by initial dilution with melted massive ice and immediate offshore transport via the thaw stream. In the mudpool and thaw stream, OM is subject to degradation, whereas in the slump floor the nitrogen decrease is caused by recolonizing vegetation. Within the nearshore zone of the ocean, heavier portions of OM are directly buried in marine sediments close to shore. We conclude that RTS have profound impacts on coastal environments in the Arctic. They mobilize nutrients from permafrost, substantially decrease OM contents and provide fresh water and nutrients at a point source.}, language = {en} } @article{TanskiBergstedtBevingtonetal.2019, author = {Tanski, George and Bergstedt, Helena and Bevington, Alexandre and Bonnaventure, Philip and Bouchard, Frederic and Coch, Caroline and Dumais, Simon and Evgrafova, Alevtina and Frauenfeld, Oliver W. and Frederick, Jennifer and Fritz, Michael and Frolov, Denis and Harder, Silvie and Hartmeyer, Ingo and Heslop, Joanne and Hoegstroem, Elin and Johansson, Margareta and Kraev, Gleb and Kuznetsova, Elena and Lenz, Josefine and Lupachev, Alexey and Magnin, Florence and Martens, Jannik and Maslakov, Alexey and Morgenstern, Anne and Nieuwendam, Alexandre and Oliva, Marc and Radosavljevi, Boris and Ramage, Justine Lucille and Schneider, Andrea and Stanilovskaya, Julia and Strauss, Jens and Trochim, Erin and Vecellio, Daniel J. and Weber, Samuel and Lantuit, Hugues}, title = {The Permafrost Young Researchers Network (PYRN) is getting older}, series = {Polar record}, volume = {55}, journal = {Polar record}, number = {4}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {0032-2474}, doi = {10.1017/S0032247418000645}, pages = {216 -- 219}, year = {2019}, abstract = {A lasting legacy of the International Polar Year (IPY) 2007-2008 was the promotion of the Permafrost Young Researchers Network (PYRN), initially an IPY outreach and education activity by the International Permafrost Association (IPA). With the momentum of IPY, PYRN developed into a thriving network that still connects young permafrost scientists, engineers, and researchers from other disciplines. This research note summarises (1) PYRN's development since 2005 and the IPY's role, (2) the first 2015 PYRN census and survey results, and (3) PYRN's future plans to improve international and interdisciplinary exchange between young researchers. The review concludes that PYRN is an established network within the polar research community that has continually developed since 2005. PYRN's successful activities were largely fostered by IPY. With >200 of the 1200 registered members active and engaged, PYRN is capitalising on the availability of social media tools and rising to meet environmental challenges while maintaining its role as a successful network honouring the legacy of IPY.}, language = {en} } @article{SchaeferLantuitRomanovskyetal.2014, author = {Schaefer, Kevin and Lantuit, Hugues and Romanovsky, Vladimir E. and Schuur, Edward A. G. and Witt, Ronald}, title = {The impact of the permafrost carbon feedback on global climate}, series = {Environmental research letters}, volume = {9}, journal = {Environmental research letters}, number = {8}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-9326}, doi = {10.1088/1748-9326/9/8/085003}, pages = {9}, year = {2014}, abstract = {Degrading permafrost can alter ecosystems, damage infrastructure, and release enough carbon dioxide (CO2) and methane (CH4) to influence global climate. The permafrost carbon feedback (PCF) is the amplification of surface warming due to CO2 and CH4 emissions from thawing permafrost. An analysis of available estimates PCF strength and timing indicate 120 +/- 85 Gt of carbon emissions from thawing permafrost by 2100. This is equivalent to 5.7 +/- 4.0\% of total anthropogenic emissions for the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathway (RCP) 8.5 scenario and would increase global temperatures by 0.29 +/- 0.21 degrees C or 7.8 +/- 5.7\%. For RCP4.5, the scenario closest to the 2 degrees C warming target for the climate change treaty, the range of cumulative emissions in 2100 from thawing permafrost decreases to between 27 and 100 Gt C with temperature increases between 0.05 and 0.15 degrees C, but the relative fraction of permafrost to total emissions increases to between 3\% and 11\%. Any substantial warming results in a committed, long-term carbon release from thawing permafrost with 60\% of emissions occurring after 2100, indicating that not accounting for permafrost emissions risks overshooting the 2 degrees C warming target. Climate projections in the IPCC Fifth Assessment Report (AR5), and any emissions targets based on those projections, do not adequately account for emissions from thawing permafrost and the effects of the PCF on global climate. We recommend the IPCC commission a special assessment focusing on the PCF and its impact on global climate to supplement the AR5 in support of treaty negotiation.}, language = {en} } @article{KleinLantuitHeimetal.2021, author = {Klein, Konstantin P. and Lantuit, Hugues and Heim, Birgit and Doxaran, David and Juhls, Bennet and Nitze, Ingmar and Walch, Daniela and Poste, Amanda and S{\o}reide, Janne E.}, title = {The Arctic Nearshore Turbidity Algorithm (ANTA)}, series = {Science of remote sensing}, volume = {4}, journal = {Science of remote sensing}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2666-0172}, doi = {10.1016/j.srs.2021.100036}, pages = {11}, year = {2021}, abstract = {The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water column and altering the biogeochemistry, but also the subsistence economy of local people, and changes in climate because of the transformation of organic matter into greenhouse gases. Yet, the quantification of suspended sediment in Arctic coastal and nearshore waters remains unsatisfactory due to the absence of dedicated algorithms to resolve the high loads occurring in the close vicinity of the shoreline. In this study we present the Arctic Nearshore Turbidity Algorithm (ANTA), the first reflectance-turbidity relationship specifically targeted towards Arctic nearshore waters that is tuned with in-situ measurements from the nearshore waters of Herschel Island Qikiqtaruk in the western Canadian Arctic. A semi-empirical model was calibrated for several relevant sensors in ocean color remote sensing, including MODIS, Sentinel 3 (OLCI), Landsat 8 (OLI), and Sentinel 2 (MSI), as well as the older Landsat sensors TM and ETM+. The ANTA performed better with Landsat 8 than with Sentinel 2 and Sentinel 3. The application of the ANTA to Sentinel 2 imagery that matches in-situ turbidity samples taken in Adventfjorden, Svalbard, shows transferability to nearshore areas beyond Herschel Island Qikiqtaruk.}, language = {en} } @article{StettnerLantuitHeimetal.2018, author = {Stettner, Samuel and Lantuit, Hugues and Heim, Birgit and Eppler, Jayson and Roth, Achim and Bartsch, Annett and Rabus, Bernhard}, title = {TerraSAR-X time series fill a gap in spaceborne snowmelt monitoring of small arctic catchments}, series = {Remote sensing}, volume = {10}, journal = {Remote sensing}, number = {7}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs10071155}, pages = {26}, year = {2018}, abstract = {The timing of snowmelt is an important turning point in the seasonal cycle of small Arctic catchments. The TerraSAR-X (TSX) satellite mission is a synthetic aperture radar system (SAR) with high potential to measure the high spatiotemporal variability of snow cover extent (SCE) and fractional snow cover (FSC) on the small catchment scale. We investigate the performance of multi-polarized and multi-pass TSX X-Band SAR data in monitoring SCE and FSC in small Arctic tundra catchments of Qikiqtaruk (Herschel Island) off the Yukon Coast in the Western Canadian Arctic. We applied a threshold based segmentation on ratio images between TSX images with wet snow and a dry snow reference, and tested the performance of two different thresholds. We quantitatively compared TSX- and Landsat 8-derived SCE maps using confusion matrices and analyzed the spatiotemporal dynamics of snowmelt from 2015 to 2017 using TSX, Landsat 8 and in situ time lapse data. Our data showed that the quality of SCE maps from TSX X-Band data is strongly influenced by polarization and to a lesser degree by incidence angle. VH polarized TSX data performed best in deriving SCE when compared to Landsat 8. TSX derived SCE maps from VH polarization detected late lying snow patches that were not detected by Landsat 8. Results of a local assessment of TSX FSC against the in situ data showed that TSX FSC accurately captured the temporal dynamics of different snow melt regimes that were related to topographic characteristics of the studied catchments. Both in situ and TSX FSC showed a longer snowmelt period in a catchment with higher contributions of steep valleys and a shorter snowmelt period in a catchment with higher contributions of upland terrain. Landsat 8 had fundamental data gaps during the snowmelt period in all 3 years due to cloud cover. The results also revealed that by choosing a positive threshold of 1 dB, detection of ice layers due to diurnal temperature variations resulted in a more accurate estimation of snow cover than a negative threshold that detects wet snow alone. We find that TSX X-Band data in VH polarization performs at a comparable quality to Landsat 8 in deriving SCE maps when a positive threshold is used. We conclude that TSX data polarization can be used to accurately monitor snowmelt events at high temporal and spatial resolution, overcoming limitations of Landsat 8, which due to cloud related data gaps generally only indicated the onset and end of snowmelt.}, language = {en} } @article{RamageIrrgangHerzschuhetal.2017, author = {Ramage, Justine Lucille and Irrgang, Anna Maria and Herzschuh, Ulrike and Morgenstern, Anne and Couture, Nicole and Lantuit, Hugues}, title = {Terrain controls on the occurrence of coastal retrogressive thaw slumps along the Yukon Coast, Canada}, series = {Journal of geophysical research : Earth surface}, volume = {122}, journal = {Journal of geophysical research : Earth surface}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9003}, doi = {10.1002/2017JF004231}, pages = {1619 -- 1634}, year = {2017}, abstract = {Retrogressive thaw slumps (RTSs) are among the most active landforms in the Arctic; their number has increased significantly over the past decades. While processes initiating discrete RTSs are well identified, the major terrain controls on the development of coastal RTSs at a regional scale are not yet defined. Our research reveals the main geomorphic factors that determine the development of RTSs along a 238km segment of the Yukon Coast, Canada. We (1) show the current extent of RTSs, (2) ascertain the factors controlling their activity and initiation, and (3) explain the spatial differences in the density and areal coverage of RTSs. We mapped and classified 287 RTSs using high-resolution satellite images acquired in 2011. We highlighted the main terrain controls over their development using univariate regression trees model. Coastal geomorphology influenced both the activity and initiation of RTSs: active RTSs and RTSs initiated after 1972 occurred primarily on terrains with slope angles greater than 3.9 degrees and 5.9 degrees, respectively. The density and areal coverage of RTSs were constrained by the volume and thickness of massive ice bodies. Differences in rates of coastal change along the coast did not affect the model. We infer that rates of coastal change averaged over a 39year period are unable to reflect the complex relationship between RTSs and coastline dynamics. We emphasize the need for large-scale studies of RTSs to evaluate their impact on the ecosystem and to measure their contribution to the global carbon budget. Plain Language Summary Retrogressive thaw slumps, henceforth slumps are a type of landslides that occur when permafrost thaws. Slumps are active landforms: they develop quickly and extend over several hectares. Satellite imagery allows to map such slumps over large areas. Our research shows where slumps develop along a 238 km segment of the Yukon Coast in Canada and explains which environments are most suitable for slump occurrence. We found that active and newly developed slumps were triggered where coastal slopes were greater than 3.9 degrees and 5.9 degrees, respectively. We explain that coastal erosion influences the development of slumps by modifying coastal slopes. We found that the highest density of slumps as well as the largest slumps occurred on terrains with high amounts of ice bodies in the ground. This study provides tools to better identify areas in the Arctic that are prone to slump development.}, language = {en} } @article{CochLamoureuxKnoblauchetal.2018, author = {Coch, Caroline and Lamoureux, Scott F. and Knoblauch, Christian and Eischeid, Isabell and Fritz, Michael and Obu, Jaroslav and Lantuit, Hugues}, title = {Summer rainfall dissolved organic carbon, solute, and sediment fluxes in a small Arctic coastal catchment on Herschel Island (Yukon Territory, Canada)}, series = {Artic science}, volume = {4}, journal = {Artic science}, number = {4}, publisher = {Canadian science publishing}, address = {Ottawa}, issn = {2368-7460}, doi = {10.1139/as-2018-0010}, pages = {750 -- 780}, year = {2018}, abstract = {Coastal ecosystems in the Arctic are affected by climate change. As summer rainfall frequency and intensity are projected to increase in the future, more organic matter, nutrients and sediment could bemobilized and transported into the coastal nearshore zones. However, knowledge of current processes and future changes is limited. We investigated streamflow dynamics and the impacts of summer rainfall on lateral fluxes in a small coastal catchment on Herschel Island in the western Canadian Arctic. For the summer monitoring periods of 2014-2016, mean dissolved organic matter flux over 17 days amounted to 82.7 +/- 30.7 kg km(-2) and mean total dissolved solids flux to 5252 +/- 1224 kg km(-2). Flux of suspended sediment was 7245 kg km(-2) in 2015, and 369 kg km(-2) in 2016. We found that 2.0\% of suspended sediment was composed of particulate organic carbon. Data and hysteresis analysis suggest a limited supply of sediments; their interannual variability is most likely caused by short-lived localized disturbances. In contrast, our results imply that dissolved organic carbon is widely available throughout the catchment and exhibits positive linear relationship with runoff. We hypothesize that increased projected rainfall in the future will result in a similar increase of dissolved organic carbon fluxes.}, language = {en} } @article{WalchSinghSoreideetal.2022, author = {Walch, Daniela M. R. and Singh, Rakesh K. and Soreide, Janne E. and Lantuit, Hugues and Poste, Amanda}, title = {Spatio-temporal variability of suspended particulate matter in a high-arctic estuary (Adventfjorden, Svalbard) using sentinel-2 time-series}, series = {Remote sensing}, volume = {14}, journal = {Remote sensing}, number = {13}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs14133123}, pages = {22}, year = {2022}, abstract = {Arctic coasts, which feature land-ocean transport of freshwater, sediments, and other terrestrial material, are impacted by climate change, including increased temperatures, melting glaciers, changes in precipitation and runoff. These trends are assumed to affect productivity in fjordic estuaries. However, the spatial extent and temporal variation of the freshwater-driven darkening of fjords remain unresolved. The present study illustrates the spatio-temporal variability of suspended particulate matter (SPM) in the Adventfjorden estuary, Svalbard, using in-situ field campaigns and ocean colour remote sensing (OCRS) via high-resolution Sentinel-2 imagery. To compute SPM concentration (C-SPMsat), a semi-analytical algorithm was regionally calibrated using local in-situ data, which improved the accuracy of satellite-derived SPM concentration by similar to 20\% (MRD). Analysis of SPM concentration for two consecutive years (2019, 2020) revealed strong seasonality of SPM in Adventfjorden. Highest estimated SPM concentrations and river plume extent (\% of fjord with C-SPMsat > 30 mg L-1) occurred during June, July, and August. Concurrently, we observed a strong relationship between river plume extent and average air temperature over the 24 h prior to the observation (R-2 = 0.69). Considering predicted changes to environmental conditions in the Arctic region, this study highlights the importance of the rapidly changing environmental parameters and the significance of remote sensing in analysing fluxes in light attenuating particles, especially in the coastal Arctic Ocean.}, language = {en} } @article{ObuLantuitFritzetal.2016, author = {Obu, Jaroslav and Lantuit, Hugues and Fritz, Michael and Pollard, Wayne H. and Sachs, Torsten and Guenther, Frank}, title = {Relation between planimetric and volumetric measurements of permafrost coast erosion: a case study from Herschel Island, western Canadian Arctic}, series = {Polar research : a Norwegian journal of Polar research}, volume = {35}, journal = {Polar research : a Norwegian journal of Polar research}, publisher = {Co-Action Publ.}, address = {Jarfalla}, issn = {0800-0395}, doi = {10.3402/polar.v35.30313}, pages = {57 -- 99}, year = {2016}, abstract = {Ice-rich permafrost coasts often undergo rapid erosion, which results in land loss and release of considerable amounts of sediment, organic carbon and nutrients, impacting the near-shore ecosystems. Because of the lack of volumetric erosion data, Arctic coastal erosion studies typically report on planimetric erosion. Our aim is to explore the relationship between planimetric and volumetric coastal erosion measurements and to update the coastal erosion rates on Herschel Island in the Canadian Arctic. We used high-resolution digital elevation models to compute sediment release and compare volumetric data to planimetric estimations of coastline movements digitized from satellite imagery. Our results show that volumetric erosion is locally less variable and likely corresponds better with environmental forcing than planimetric erosion. Average sediment release volumes are in the same range as sediment release volumes calculated from coastline movements combined with cliff height. However, the differences between these estimates are significant for small coastal sections. We attribute the differences between planimetric and volumetric coastal erosion measurements to mass wasting, which is abundant along the coasts of Herschel Island. The average recorded coastline retreat on Herschel Island was 0.68m a(-1) for the period 2000-2011. Erosion rates increased by more than 50\% in comparison with the period 1970-2000, which is in accordance with a recently observed increase along the Alaskan Beaufort Sea. The estimated annual sediment release was 28.2 m(3) m(-1) with resulting fluxes of 590 kg C m(-1) and 104 kg N m(-1).}, language = {en} } @article{FritzUnkelLenzetal.2018, author = {Fritz, Michael and Unkel, Ingmar and Lenz, Josefine and Gajewski, Konrad and Frenzel, Peter and Paquette, Nathalie and Lantuit, Hugues and K{\"o}rte, Lisa and Wetterich, Sebastian}, title = {Regional environmental change versus local signal preservation in Holocene thermokarst lake sediments}, series = {Journal of paleolimnolog}, volume = {60}, journal = {Journal of paleolimnolog}, number = {1}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-018-0025-0}, pages = {77 -- 96}, year = {2018}, abstract = {Thermokarst lakes cover nearly one fourth of ice-rich permafrost lowlands in the Arctic. Sediments from an athalassic subsaline thermokarst lake on Herschel Island (69°36′N; 139°04′W, Canadian Arctic) were used to understand regional changes in climate and in sediment transport, hydrology, nutrient availability and permafrost disturbance. The sediment record spans the last ~ 11,700 years and the basal date is in good agreement with the Holocene onset of thermokarst initiation in the region. Electrical conductivity in pore water continuously decreases, thus indicating desalinization and continuous increase of lake size and water level. The inc/coh ratio of XRF scans provides a high-resolution organic-carbon proxy which correlates with TOC measurements. XRF-derived Mn/Fe ratios indicate aerobic versus anaerobic conditions which moderate the preservation potential of organic matter in lake sediments. The coexistence of marine, brackish and freshwater ostracods and foraminifera is explained by (1) oligohaline to mesohaline water chemistry of the past lake and (2) redeposition of Pleistocene specimens found within upthrusted marine sediments around the lake. Episodes of catchment disturbance are identified when calcareous fossils and allochthonous material were transported into the lake by thermokarst processes such as active-layer detachments, slumping and erosion of ice-rich shores. The pollen record does not show major variations and the pollen-based climate record does not match well with other summer air temperature reconstructions from this region. Local vegetation patterns in small catchments are strongly linked to morphology and sub-surface permafrost conditions rather than to climate. Multidisciplinary studies can identify the onset and life cycle of thermokarst lakes as they play a crucial role in Arctic freshwater ecosystems and in the global carbon cycle of the past, present and future.}, language = {en} } @article{TanskiWagnerKnoblauchetal.2019, author = {Tanski, Georg and Wagner, Dirk and Knoblauch, Christian and Fritz, Michael and Sachs, Torsten and Lantuit, Hugues}, title = {Rapid CO2 Release From Eroding Permafrost in Seawater}, series = {Geophysical research letters}, volume = {46}, journal = {Geophysical research letters}, number = {20}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1029/2019GL084303}, pages = {11244 -- 11252}, year = {2019}, language = {en} } @article{BiskabornSmithNoetzlietal.2019, author = {Biskaborn, Boris and Smith, Sharon L. and Noetzli, Jeannette and Matthes, Heidrun and Vieira, Goncalo and Streletskiy, Dmitry A. and Schoeneich, Philippe and Romanovsky, Vladimir E. and Lewkowicz, Antoni G. and Abramov, Andrey and Allard, Michel and Boike, Julia and Cable, William L. and Christiansen, Hanne H. and Delaloye, Reynald and Diekmann, Bernhard and Drozdov, Dmitry and Etzelmueller, Bernd and Grosse, Guido and Guglielmin, Mauro and Ingeman-Nielsen, Thomas and Isaksen, Ketil and Ishikawa, Mamoru and Johansson, Margareta and Johannsson, Halldor and Joo, Anseok and Kaverin, Dmitry and Kholodov, Alexander and Konstantinov, Pavel and Kroeger, Tim and Lambiel, Christophe and Lanckman, Jean-Pierre and Luo, Dongliang and Malkova, Galina and Meiklejohn, Ian and Moskalenko, Natalia and Oliva, Marc and Phillips, Marcia and Ramos, Miguel and Sannel, A. Britta K. and Sergeev, Dmitrii and Seybold, Cathy and Skryabin, Pavel and Vasiliev, Alexander and Wu, Qingbai and Yoshikawa, Kenji and Zheleznyak, Mikhail and Lantuit, Hugues}, title = {Permafrost is warming at a global scale}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/s41467-018-08240-4}, pages = {11}, year = {2019}, abstract = {Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature change has been compiled. Here we use a global data set of permafrost temperature time series from the Global Terrestrial Network for Permafrost to evaluate temperature change across permafrost regions for the period since the International Polar Year (2007-2009). During the reference decade between 2007 and 2016, ground temperature near the depth of zero annual amplitude in the continuous permafrost zone increased by 0.39 +/- 0.15 degrees C. Over the same period, discontinuous permafrost warmed by 0.20 +/- 0.10 degrees C. Permafrost in mountains warmed by 0.19 +/- 0.05 degrees C and in Antarctica by 0.37 +/- 0.10 degrees C. Globally, permafrost temperature increased by 0.29 +/- 0.12 degrees C. The observed trend follows the Arctic amplification of air temperature increase in the Northern Hemisphere. In the discontinuous zone, however, ground warming occurred due to increased snow thickness while air temperature remained statistically unchanged.}, language = {en} } @article{FrankFahleYergeauGreeretal.2014, author = {Frank-Fahle, Beatrice A. and Yergeau, Etienne and Greer, Charles W. and Lantuit, Hugues and Wagner, Dirk}, title = {Microbial functional potential and community composition in permafrost-affected soils of the NW canadian arctic}, series = {PLoS one}, volume = {9}, journal = {PLoS one}, number = {1}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0084761}, pages = {12}, year = {2014}, abstract = {Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic.}, language = {en} } @article{KleinLantuitHeimetal.2019, author = {Klein, Konstantin P. and Lantuit, Hugues and Heim, Birgit and Fell, Frank and Doxaran, David and Irrgang, Anna Maria}, title = {Long-Term High-Resolution Sediment and Sea Surface Temperature Spatial Patterns in Arctic Nearshore Waters Retrieved Using 30-Year Landsat Archive Imagery}, series = {Remote sensing}, volume = {11}, journal = {Remote sensing}, number = {23}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs11232791}, pages = {21}, year = {2019}, abstract = {The Arctic is directly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems, the subsistence economy of the local population, and the climate because of the transformation of organic matter into greenhouse gases. Yet, the patterns of sediment dispersal in the nearshore zone are not well known, because ships do not often reach shallow waters and satellite remote sensing is traditionally focused on less dynamic environments. The goal of this study is to use the extensive Landsat archive to investigate sediment dispersal patterns specifically on an exemplary Arctic nearshore environment, where field measurements are often scarce. Multiple Landsat scenes were combined to calculate means of sediment dispersal and sea surface temperature under changing seasonal wind conditions in the nearshore zone of Herschel Island Qikiqtaruk in the western Canadian Arctic since 1982. We use observations in the Landsat red and thermal wavebands, as well as a recently published water turbidity algorithm to relate archive wind data to turbidity and sea surface temperature. We map the spatial patterns of turbidity and water temperature at high spatial resolution in order to resolve transport pathways of water and sediment at the water surface. Our results show that these pathways are clearly related to the prevailing wind conditions, being ESE and NW. During easterly wind conditions, both turbidity and water temperature are significantly higher in the nearshore area. The extent of the Mackenzie River plume and coastal erosion are the main explanatory variables for sediment dispersal and sea surface temperature distributions in the study area. During northwesterly wind conditions, the influence of the Mackenzie River plume is negligible. Our results highlight the potential of high spatial resolution Landsat imagery to detect small-scale hydrodynamic processes, but also show the need to specifically tune optical models for Arctic nearshore environments.}, language = {en} } @article{FritzHerzschuhWetterichetal.2012, author = {Fritz, Michael and Herzschuh, Ulrike and Wetterich, Sebastian and Lantuit, Hugues and De Pascale, Gregory P. and Pollard, Wayne H. and Schirrmeister, Lutz}, title = {Late glacial and holocene sedimentation, vegetation, and climate history from easternmost Beringia (northern Yukon Territory, Canada)}, series = {Quaternary research : an interdisciplinary journal}, volume = {78}, journal = {Quaternary research : an interdisciplinary journal}, number = {3}, publisher = {Elsevier}, address = {San Diego}, issn = {0033-5894}, doi = {10.1016/j.yqres.2012.07.007}, pages = {549 -- 560}, year = {2012}, abstract = {Beringian climate and environmental history are poorly characterized at its easternmost edge. Lake sediments from the northern Yukon Territory have recorded sedimentation, vegetation, summer temperature and precipitation changes since similar to 16 cal ka BP. Herb-dominated tundra persisted until similar to 14.7 cal ka BP with mean July air temperatures <= 5 degrees C colder and annual precipitation 50 to 120 mm lower than today. Temperatures rapidly increased during the Bolling/Allerod interstadial towards modern conditions, favoring establishment of Betula-Salix shrub tundra. Pollen-inferred temperature reconstructions recorded a pronounced Younger Dryas stadial in east Beringia with a temperature drop of similar to 1.5 degrees C (similar to 2.5 to 3.0 degrees C below modern conditions) and low net precipitation (90 to 170 mm) but show little evidence of an early Holocene thermal maximum in the pollen record. Sustained low net precipitation and increased evaporation during early Holocene warming suggest a moisture-limited spread of vegetation and an obscured summer temperature maximum. Northern Yukon Holocene moisture availability increased in response to a retreating Laurentide Ice Sheet, postglacial sea level rise, and decreasing summer insolation that in turn led to establishment of Alnus-Berula shrub tundra from similar to 5 cal ka BP until present, and conversion of a continental climate into a coastal-maritime climate near the Beaufort Sea.}, language = {en} } @article{RamageIrrgangMorgensternetal.2018, author = {Ramage, Justine Lucille and Irrgang, Anna Maria and Morgenstern, Anne and Lantuit, Hugues}, title = {Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean}, series = {Biogeosciences}, volume = {15}, journal = {Biogeosciences}, number = {5}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-15-1483-2018}, pages = {1483 -- 1495}, year = {2018}, abstract = {Retrogressive thaw slumps (RTSs) are among the most active thermokarst landforms in the Arctic and deliver a large amount of material to the Arctic Ocean. However, their contribution to the organic carbon (OC) budget is unknown. We provide the first estimate of the contribution of RTSs to the nearshore OC budget of the Yukon Coast, Canada, and describe the evolution of coastal RTSs between 1952 and 2011 in this area. We (1) describe the evolution of RTSs between 1952 and 2011; (2) calculate the volume of eroded material and stocks of OC mobilized through slumping, including soil organic carbon (SOC) and dissolved organic carbon (DOC); and (3) estimate the OC fluxes mobilized through slumping between 1972 and 2011. We identified RTSs using high- resolution satellite imagery from 2011 and geocoded aerial photographs from 1952 and 1972. To estimate the volume of eroded material, we applied spline interpolation on an airborne lidar dataset acquired in July 2013. We inferred the stocks of mobilized SOC and DOC from existing related literature. Our results show a 73\% increase in the number of RTSs and 14\% areal expansion between 1952 and 2011. In the study area, RTSs displaced at least 16.6 x 10(6) m(3) of material, 53\% of which was ice, and mobilized 145.9 x 10(6) kg of OC. Between 1972 and 2011, 49 RTSs displaced 8.6 x 10(3) m(3) yr(-1) of material, adding 0.6\% to the OC flux released by coastal retreat along the Yukon Coast. Our results show that the contribution of RTSs to the nearshore OC budget is non-negligible and should be included when estimating the quantity of OC released from the Arctic coast to the ocean.}, language = {en} } @article{IrrgangLantuitGordonetal.2019, author = {Irrgang, Anna Maria and Lantuit, Hugues and Gordon, Richard R. and Piskor, Ashley and Manson, Gavin K.}, title = {Impacts of past and future coastal changes on the Yukon coast - threats for cultural sites, infrastructure, and travel routes}, series = {Arctic Science}, volume = {5}, journal = {Arctic Science}, number = {2}, publisher = {Canadian Science Publishing}, address = {Ottawa}, issn = {2368-7460}, doi = {10.1139/as-2017-0041}, pages = {107 -- 126}, year = {2019}, abstract = {Yukon's Beaufort coast, Canada, is a highly dynamic landscape. Cultural sites, infrastructure, and travel routes used by the local population are particularly vulnerable to coastal erosion. To assess threats to these phenomena, rates of shoreline change for a 210 km length of the coast were analyzed and combined with socioeconomic and cultural information. Rates of shoreline change were derived from aerial and satellite imagery from the 1950s, 1970s, 1990s, and 2011. Using these data, conservative (S1) and dynamic (S2) shoreline projections were constructed to predict shoreline positions for the year 2100. The locations of cultural features in the archives of a Parks Canada database, the Yukon Archaeological Program, and as reported in other literature were combined with projected shoreline position changes. Between 2011 and 2100, approximately 850 ha (S1) and 2660 ha (S2) may erode, resulting in a loss of 45\% (S1) to 61\% (S2) of all cultural features by 2100. The last large, actively used camp area and two nearshore landing strips will likely be threatened by future coastal processes. Future coastal erosion and sedimentation processes are expected to increasingly threaten cultural sites and influence travelling and living along the Yukon coast.}, language = {en} } @article{FritzWolterRudayaetal.2016, author = {Fritz, Michael and Wolter, Juliane and Rudaya, Natalia and Palagushkina, Olga and Nazarova, Larisa B. and Obu, Jaroslav and Rethemeyer, Janet and Lantuit, Hugues and Wetterich, Sebastian}, title = {Holocene ice-wedge polygon development in northern Yukon permafrost peatlands (Canada)}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {147}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2016.02.008}, pages = {279 -- 297}, year = {2016}, abstract = {Ice-wedge polygon (IWP) peatlands in the Arctic and Subarctic are extremely vulnerable to climatic and environmental change. We present the results of a multidisciplinary paleoenvironmental study on IWPs in the northern Yukon, Canada. High-resolution laboratory analyses were carried out on a permafrost core and the overlying seasonally thawed (active) layer, from an IWP located in a drained lake basin on Herschel Island. In relation to 14 Accelerator Mass Spectrometry (AMS) radiocarbon dates spanning the last 5000 years, we report sedimentary data including grain size distribution and biogeochemical parameters (organic carbon, nitrogen, C/N ratio, delta C-13), stable water isotopes (delta O-18, delta D), as well as fossil pollen, plant macrofossil and diatom assemblages. Three sediment units (SUS) correspond to the main stages of deposition (1) in a thermokarst lake (SW : 4950 to 3950 cal yrs BP), (2) during transition from lacustrine to palustrine conditions after lake drainage (SU2: 3950 to 3120 cal yrs BP), and (3) in palustrine conditions of the IWP field that developed after drainage (SU3: 3120 cal yrs BP to 2012 CE). The lacustrine phase (pre 3950 cal yrs BP) is characterized by planktonic-benthic and pioneer diatom species indicating circumneutral waters, and very few plant macrofossils. The pollen record has captured a regional signal of relatively stable vegetation composition and climate for the lacustrine stage of the record until 3950 cal yrs BP. Palustrine conditions with benthic and acidophilic diatom species characterize the peaty shallow-water environments of the low-centered IWP. The transition from lacustrine to palustrine conditions was accompanied by acidification and rapid revegetation of the lake bottom within about 100 years. Since the palustrine phase we consider the pollen record as a local vegetation proxy dominated by the plant communities growing in the IWP. Ice-wedge cracking in water-saturated sediments started immediately after lake drainage at about 3950 cal yrs BP and led to the formation of an IWP mire. Permafrost aggradation through downward closed-system freezing of the lake talik is indicated by the stable water isotope record. The originally submerged IWP center underwent gradual drying during the past 2000 years. This study highlights the sensitivity of permafrost landscapes to climate and environmental change throughout the Holocene. (C) 2016 Elsevier Ltd. All rights reserved.}, language = {en} }