TY - JOUR A1 - Ramage, Justine Lucille A1 - Irrgang, Anna Maria A1 - Herzschuh, Ulrike A1 - Morgenstern, Anne A1 - Couture, Nicole A1 - Lantuit, Hugues T1 - Terrain controls on the occurrence of coastal retrogressive thaw slumps along the Yukon Coast, Canada JF - Journal of geophysical research : Earth surface N2 - 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. KW - permafrost degradation KW - retrogressive thaw slumps KW - coastal erosion KW - Arctic KW - coastal geomorphology Y1 - 2017 U6 - https://doi.org/10.1002/2017JF004231 SN - 2169-9003 SN - 2169-9011 VL - 122 SP - 1619 EP - 1634 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Wolter, Juliane A1 - Lantuit, Hugues A1 - Wetterich, Sebastian A1 - Rethemeyer, Janet A1 - Fritz, Michael T1 - Climatic, geomorphologic and hydrologic perturbations as drivers for mid- to late Holocene development of ice-wedge polygons in the western Canadian Arctic JF - Permafrost and Periglacial Processes N2 - Ice-wedge polygons are widespread periglacial features and influence landscape hydrology and carbon storage. The influence of climate and topography on polygon development is not entirely clear, however, giving high uncertainties to projections of permafrost development. We studied the mid- to late Holocene development of modern ice-wedge polygon sites to explore drivers of change and reasons for long-term stability. We analyzed organic carbon, total nitrogen, stable carbon isotopes, grain size composition and plant macrofossils in six cores from three polygons. We found that ail sites developed from aquatic to wetland conditions. In the mid-Holocene, shallow lakes and partly submerged ice-wedge polygons existed at the studied sites. An erosional hiatus of ca 5000 years followed, and ice-wedge polygons re-initiated within the last millennium. Ice-wedge melt and surface drying during the last century were linked to climatic warming. The influence of climate on ice-wedge polygon development was outweighed by geomorphology during most of the late Holocene. Recent warming, however, caused ice-wedge degradation at all sites. Our study showed that where waterlogged ground was maintained, low-centered polygons persisted for millennia. Ice-wedge melt and increased drainage through geomorphic disturbance, however, triggered conversion into high-centered polygons and may lead to self-enhancing degradation under continued warming. KW - carbon KW - lowland coasts KW - permafrost degradation KW - plant macrofossil analysis KW - tundra vegetation KW - western Canadian Arctic Y1 - 2018 U6 - https://doi.org/10.1002/ppp.1977 SN - 1045-6740 SN - 1099-1530 VL - 29 IS - 3 SP - 164 EP - 181 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Morgenstern, Anne A1 - Overduin, Pier Paul A1 - Günther, Frank A1 - Stettner, Samuel A1 - Ramage, Justine A1 - Schirrmeister, Lutz A1 - Grigoriev, Mikhail N. A1 - Grosse, Guido T1 - Thermo-erosional valleys in Siberian ice-rich permafrost JF - Permafrost and Periglacial Processes N2 - Thermal erosion is a major mechanism of permafrost degradation, resulting in characteristic landforms. We inventory thermo-erosional valleys in ice-rich coastal lowlands adjacent to the Siberian Laptev Sea based on remote sensing, Geographic Information System (GIS), and field investigations for a first regional assessment of their spatial distribution and characteristics. Three study areas with similar geological (Yedoma Ice Complex) but diverse geomorphological conditions vary in valley areal extent, incision depth, and branching geometry. The most extensive valley networks are incised deeply (up to 35 m) into the broad inclined lowland around Mamontov Klyk. The flat, low-lying plain forming the Buor Khaya Peninsula is more degraded by thermokarst and characterized by long valleys of lower depth with short tributaries. Small, isolated Yedoma Ice Complex remnants in the Lena River Delta predominantly exhibit shorter but deep valleys. Based on these hydrographical network and topography assessments, we discuss geomorphological and hydrological connections to erosion processes. Relative catchment size along with regional slope interact with other Holocene relief-forming processes such as thermokarst and neotectonics. Our findings suggest that thermo-erosional valleys are prominent, hitherto overlooked permafrost degradation landforms that add to impacts on biogeochemical cycling, sediment transport, and hydrology in the degrading Siberian Yedoma Ice Complex. KW - geomorphology KW - periglacial landscapes KW - permafrost degradation KW - thermal KW - erosion KW - valley distribution KW - Yedoma Ice Complex Y1 - 2020 U6 - https://doi.org/10.1002/ppp.2087 SN - 1045-6740 SN - 1099-1530 VL - 32 IS - 1 SP - 59 EP - 75 PB - Wiley CY - Hoboken ER -