Debris cover on thaw slumps and its insulative role in a warming climate
Thaw slumps in ice‐rich permafrost can retreat tens of metres per summer, driven by the melt of subaerially exposed ground ice. However, some slumps retain an ice‐veneering debris cover as they retreat. A quantitative understanding of the thermal regime and geomorphic evolution of debris‐covered slu...
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ftawi:oai:epic.awi.de:52307 2023-05-15T15:12:29+02:00 Debris cover on thaw slumps and its insulative role in a warming climate Zwieback, S. Boike, Julia Marsh, P. Berg, A. 2020-06-16 https://epic.awi.de/id/eprint/52307/ https://doi.org/10.1002/esp.4919 https://hdl.handle.net/10013/epic.ff33c487-34f3-43f1-ac9f-653b0df71c52 unknown Wiley Zwieback, S. , Boike, J. orcid:0000-0002-5875-2112 , Marsh, P. and Berg, A. (2020) Debris cover on thaw slumps and its insulative role in a warming climate , Earth Surface Processes and Landforms . doi:10.1002/esp.4919 <https://doi.org/10.1002/esp.4919> , hdl:10013/epic.ff33c487-34f3-43f1-ac9f-653b0df71c52 EPIC3Earth Surface Processes and Landforms, Wiley, ISSN: 0197-9337 Article isiRev 2020 ftawi https://doi.org/10.1002/esp.4919 2022-10-23T23:12:44Z Thaw slumps in ice‐rich permafrost can retreat tens of metres per summer, driven by the melt of subaerially exposed ground ice. However, some slumps retain an ice‐veneering debris cover as they retreat. A quantitative understanding of the thermal regime and geomorphic evolution of debris‐covered slumps in a warming climate is largely lacking. To characterize the thermal regime, we instrumented four debris‐covered slumps in the Canadian Low Arctic and developed a numerical conduction‐based model. The observed surface temperatures 20°C and steep thermal gradients indicate that debris insulates the ice by shifting the energy balance towards radiative and turbulent losses. After the model was calibrated and validated with field observations, it predicted sub‐debris ice melt to decrease four‐fold from 1.9 to 0.5 m as the thickness of the fine‐grained debris quadruples from 0.1 to 0.4 m. With warming temperatures, melt is predicted to increase most rapidly, in relative terms, for thick (~0.5‐1.0 m) debris covers. The morphology and evolution of the debris‐covered slumps were characterized using field and remote sensing observations, which revealed differences in association with morphology and debris composition. Two low‐angle slumps retreated continually despite their persistent fine‐grained debris covers. The observed elevation losses decreased from ~1.0 m/yr where debris thickness ~.2 m to 0.1 m/yr where thickness ~1.0 m. Conversely, a steep slump with a coarse‐grained debris veneer underwent short‐lived bursts of retreat, hinting at a complex interplay of positive and negative feedback processes. The insulative protection and behaviour of debris vary significantly with factors such as thickness, grain size and climate: debris thus exerts a fundamental, spatially variable influence on slump trajectories in a warming climate. Article in Journal/Newspaper Arctic Ice permafrost Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Arctic Earth Surface Processes and Landforms 45 11 2631 2646 |
institution |
Open Polar |
collection |
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Thaw slumps in ice‐rich permafrost can retreat tens of metres per summer, driven by the melt of subaerially exposed ground ice. However, some slumps retain an ice‐veneering debris cover as they retreat. A quantitative understanding of the thermal regime and geomorphic evolution of debris‐covered slumps in a warming climate is largely lacking. To characterize the thermal regime, we instrumented four debris‐covered slumps in the Canadian Low Arctic and developed a numerical conduction‐based model. The observed surface temperatures 20°C and steep thermal gradients indicate that debris insulates the ice by shifting the energy balance towards radiative and turbulent losses. After the model was calibrated and validated with field observations, it predicted sub‐debris ice melt to decrease four‐fold from 1.9 to 0.5 m as the thickness of the fine‐grained debris quadruples from 0.1 to 0.4 m. With warming temperatures, melt is predicted to increase most rapidly, in relative terms, for thick (~0.5‐1.0 m) debris covers. The morphology and evolution of the debris‐covered slumps were characterized using field and remote sensing observations, which revealed differences in association with morphology and debris composition. Two low‐angle slumps retreated continually despite their persistent fine‐grained debris covers. The observed elevation losses decreased from ~1.0 m/yr where debris thickness ~.2 m to 0.1 m/yr where thickness ~1.0 m. Conversely, a steep slump with a coarse‐grained debris veneer underwent short‐lived bursts of retreat, hinting at a complex interplay of positive and negative feedback processes. The insulative protection and behaviour of debris vary significantly with factors such as thickness, grain size and climate: debris thus exerts a fundamental, spatially variable influence on slump trajectories in a warming climate. |
format |
Article in Journal/Newspaper |
author |
Zwieback, S. Boike, Julia Marsh, P. Berg, A. |
spellingShingle |
Zwieback, S. Boike, Julia Marsh, P. Berg, A. Debris cover on thaw slumps and its insulative role in a warming climate |
author_facet |
Zwieback, S. Boike, Julia Marsh, P. Berg, A. |
author_sort |
Zwieback, S. |
title |
Debris cover on thaw slumps and its insulative role in a warming climate |
title_short |
Debris cover on thaw slumps and its insulative role in a warming climate |
title_full |
Debris cover on thaw slumps and its insulative role in a warming climate |
title_fullStr |
Debris cover on thaw slumps and its insulative role in a warming climate |
title_full_unstemmed |
Debris cover on thaw slumps and its insulative role in a warming climate |
title_sort |
debris cover on thaw slumps and its insulative role in a warming climate |
publisher |
Wiley |
publishDate |
2020 |
url |
https://epic.awi.de/id/eprint/52307/ https://doi.org/10.1002/esp.4919 https://hdl.handle.net/10013/epic.ff33c487-34f3-43f1-ac9f-653b0df71c52 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Ice permafrost |
genre_facet |
Arctic Ice permafrost |
op_source |
EPIC3Earth Surface Processes and Landforms, Wiley, ISSN: 0197-9337 |
op_relation |
Zwieback, S. , Boike, J. orcid:0000-0002-5875-2112 , Marsh, P. and Berg, A. (2020) Debris cover on thaw slumps and its insulative role in a warming climate , Earth Surface Processes and Landforms . doi:10.1002/esp.4919 <https://doi.org/10.1002/esp.4919> , hdl:10013/epic.ff33c487-34f3-43f1-ac9f-653b0df71c52 |
op_doi |
https://doi.org/10.1002/esp.4919 |
container_title |
Earth Surface Processes and Landforms |
container_volume |
45 |
container_issue |
11 |
container_start_page |
2631 |
op_container_end_page |
2646 |
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1766343150092156928 |