Past and recent thermal erosion degrades Siberian Yedoma

• Main Authors: Morgenstern, Anne, Günther, Frank, Overduin, Paul, Stettner, Samuel, Fedorova, I., Chetverova, A., Bobrova, O., Bornemann, Niko, Eulenburg, Antje, Niemann, Sascha, Boike, Julia, Grosse, Guido, Heim, Birgit, Schirrmeister, Lutz
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Arctic; Laptev Sea; Ice; laptev; lena delta; permafrost; Thermokarst
• Online Access: https://epic.awi.de/id/eprint/35912/; https://hdl.handle.net/10013/epic.43828

The high thaw vulnerability of Yedoma (Ice Complex) in combination with its high contents of labile organic matter makes these ice-rich permafrost deposits an object of research activities that investigate permafrost degradation and the permafrost-carbon feedback under a warming climate. Thermokarst and thermal erosion are two major types of permafrost degradation in Arctic lowlands, and in particular Yedoma landscapes. These processes and resulting landforms release fossil organic matter to the atmosphere and the hydrological system, and may also substantially alter the water and energy balances of the affected landscapes. While thermokarst has been widely investigated, data is sparse on thermal erosion, despite the fact that related landforms, such as thermo-erosional gullies, valleys and valley networks, cover vast parts of Yedoma landscapes. We investigate 1) the impact of past thermo-erosional processes on the transformation of the Late Pleistocene Yedoma relief in the Siberian Laptev Sea region to the recent relief situation and 2) the impact of recent thermo-erosional processes and landforms on the hydrological and biogeochemical regime of Yedoma landscapes. Our regional inventory of thermo-erosional landforms using GIS-based analysis of remote sensing data, digital elevation models, and field investigations demonstrates that thermal erosion severely affected Siberian Yedoma during the Holocene, in some regions much more than thermokarst. Strong variations in the morphology and spatial distribution of streams and valleys are observed and can be attributed to differences in the size and relief characteristics of the study areas as well as to their predominant cryolithological properties, which are also influenced by degradation of the Yedoma by thermokarst prior to thermal erosion. Investigations of recent thermo-erosional processes focused on a key area in the central Lena Delta, Kurungnakh Island. We compare and contrast discharge regimes and mass fluxes of different thermo-erosional landforms draining different surface and relief types of this Yedoma landscape on the basis of field measurements and water sample analyses.