Search

Your search keyword '"Kokelj, S. V."' showing total 96 results
Start Over Author "Kokelj, S. V."
96 results on '"Kokelj, S. V."'

15. Mapping and understanding the vulnerability of northern peatlands to permafrost thaw at scales relevant to community adaptation planning

Author

Gibson, C., Cottenie, K., Gingras-Hill, T., Kokelj, S. V., Baltzer, J. L., Chasmer, Laura, Turetsky, M. R., Gibson, C., Cottenie, K., Gingras-Hill, T., Kokelj, S. V., Baltzer, J. L., Chasmer, Laura, and Turetsky, M. R.

Abstract

Developing spatially explicit permafrost datasets and climate assessments at scales relevant to northern communities is increasingly important as land users and decision makers incorporate changing permafrost conditions in community and adaptation planning. This need is particularly strong within the discontinuous permafrost zone of the Northwest Territories (NWT) Canada where permafrost peatlands are undergoing rapid thaw due to a warming climate. Current data products for predicting landscapes at risk of thaw are generally built at circumpolar scales and do not lend themselves well to fine-scale regional interpretations. Here, we present a new permafrost vulnerability dataset that assesses the degree of permafrost thaw within peatlands across a 750 km latitudinal gradient in the NWT. This updated dataset provides spatially explicit estimates of where peatland thermokarst potential exists, thus making it much more suitable for local, regional or community usage. Within southern peatland complexes, we show that permafrost thaw affects up to 70% of the peatland area and that thaw is strongly mediated by both latitude and elevation, with widespread thaw occuring particularly at low elevations. At the northern end of our latitudinal gradient, peatland permafrost remains climate-protected with relatively little thaw. Collectively these results demonstrate the importance of scale in permafrost analyses and mapping if research is to support northern communities and decision makers in a changing climate. This study offers a more scale-appropriate approach to support community adaptative planning under scenarios of continued warming and widespread permafrost thaw.

Published
2021

23. A New Protocol to Map Permafrost Geomorphic Features and Advance Thaw-Susceptibility Modelling.

Author

Rudy, A. C. A., Morse, P. D., Kokelj, S. V., Sladen, W. E., and Smith, S. L.

Abstract

Permafrost thaw can destabilize terrain, initiate thermokarst processes that alter landscapes, and create geohazards for communities and infrastructure. A robust, standardized methodology was developed to map indicators of thaw-sensitive permafrost terrain, including mass wasting and periglacial features. The method was applied to a 10-km wide corridor centred on the Dempster and Inuvik-Tuktoyaktuk Highways, which are constructed over a wide range of terrain and permafrost conditions. Here we use random forest models, trained and validated with mass movement and ice-wedge polygon inventories, to develop thaw-susceptibility models for two regions along the corridor, Peel Plateau, and Anderson Plain and Tuktoyaktuk Coastlands. Geomorphological and hydrological variables were used as predictors providing insights into the characteristics constraining the distribution of thaw-sensitive terrain. In the Peel region, mass movements have a higher potential of occurring on concave, moderate to steep slopes (7 to 18°) in fluvially-incised valleys. In uplands of Anderson Plain and Tuktoyaktuk Coastlands, mass movements occur on moderate slopes (5 to 15°) adjacent to incised stream channels, and along lakeshores. The ice-wedge polygon model across the forest tundra transition north of Inuvik highlights the northward increase in polygonal terrain with decreasing ground temperatures. [ABSTRACT FROM AUTHOR]

Published
2019

24. Thermal Regime of Stream Channels in Continuous Permafrost, Western Canadian Arctic.

Author

Ensom, T., Kokelj, S. V., and Marsh, P.

Abstract

In permafrost regions, the movement of water during winter has important implications for hydrology, land use, and infrastructure. Knowledge of winter hydrothermal dynamics in small, extensive tundra stream networks is limited. Climate warming, changing precipitation regimes, and increases in tundra vegetation coverage may delay active layer freeze-back, potentially increasing winter water movement. The primary goals of this research are to improve knowledge of the thermal regime of small stream channels in continuous permafrost, explore the implications of a changing climate and runoff, and describe the influence of infrastructure on channel thermal regime. A program of temperature monitoring in stream channel beds and riparian margins between Inuvik and Tuktoyaktuk is presented here. Preliminary results, if representative of several years, suggest that permafrost is not present at depths shallower than 3.5 m below the bed of a small stream with a contributing area of ~30 km2, and that this layer does not likely re-freeze during winter. This thermal regime may be modified by highway crossings that reduce or eliminate stream snow cover, and the degree of thermal disturbance may be a function of contributing watershed size. This research and further related work have the potential to provide new insight on channel thermal regime and winter hydrology in permafrost regions, offer projections of change in the context of a warming climate, and help inform the design, operation, and mitigation of hydrological issues associated with linear infrastructure in permafrost. [ABSTRACT FROM AUTHOR]

Published
2019

34. The Occurrence and Thermal Disequilibrium State of Permafrost in Forest Ecotopes of the Great Slave Region, Northwest Territories, Canada.

Author

Morse, P. D., Wolfe, S. A., Kokelj, S. V., and Gaanderse, A. J. R.

Subjects
PERMAFROST, LATENT heat, EARTH temperature, PEATLANDS
Abstract

ABSTRACT Permafrost underlies peatlands of the Great Slave region, Northwest Territories, Canada, but permafrost relations beneath other ecotopes of black spruce ( Picea mariana), white birch ( Betula papyrifera) and mixed forests remain unknown. Permafrost-ecotope relations examined over a 3 year period (2010-13) establish the occurrence and thermal state of permafrost under these different types of forest. Air temperatures and snow depths are regionally consistent. Ground temperature variation primarily reflects latent heat effects during the freezing season, with the duration of season-normalised active-layer freezeback explaining 76% of 1 m ground temperature variation among all sites except xeric peatland. Low apparent thermal diffusivities from substantial latent heat effects strongly attenuate ground temperature variation with depth, and yield zero annual amplitude depths of 7 m or less where annual mean ground temperatures range among sites from -1.4 °C to 0.0 °C. Extensive discontinuous permafrost conditions, related to the extent of forested ecotopes, are commonly in thermal disequilibrium. Whereas permafrost in peatlands may be ecosystem-protected, this represents only about 2% of the area of the region. Permafrost in other forested ecotopes, occurring in ice-rich unconsolidated sediments, is climate-driven and ecosystem-protected because of latent heat effects. Though the rate of permafrost degradation may be reduced, an eventual transition to isolated permafrost retained primarily within ecosystem-driven peatlands implies substantial reductions of permafrost extent in this region. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

46. Factors influencing permafrost temperatures across tree line in the uplands east of the Mackenzie Delta, 2004-2010.

Author

Palmer, M. J., Burn, C. R., and Kokelj, S. V.

Subjects
PERMAFROST, EARTH temperature, TIMBERLINE, UPLANDS, THERMAL analysis, WINTER
Abstract

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2012
Full Text
View/download PDF

47. Lake- and channel-bottom temperatures in the Mackenzie Delta, Northwest Territories.

Author

Ensom, T. P., Burn, C. R., and Kokelj, S. V.

Subjects
EARTH temperature, HYDROLOGY, FORESTS & forestry, DISTRIBUTION (Probability theory)
Abstract

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2012
Full Text
View/download PDF

48. Influence of snow on near-surface ground temperatures in upland and alluvial environments of the outer Mackenzie Delta, Northwest Territories.

Author

Morse, P. D., Burn, C. R., and Kokelj, S. V.

Subjects
EARTH temperature, SNOW, UPLANDS, ALLUVIAL plains, SOIL moisture
Abstract

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2012
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results