Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada
ABSTRACT Annual and seasonal surface velocities measured continuously from 1960 to 1970 at White Glacier, a 14 km long polythermal valley glacier spanning ~100–1800 m a.s.l., provide the most comprehensive early record of ice dynamics in the Canadian Arctic. Through comparison with differential GPS-...
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Language: | English |
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2017
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Online Access: | http://dx.doi.org/10.1017/jog.2017.3 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301700003X |
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crcambridgeupr:10.1017/jog.2017.3 2023-06-11T04:09:13+02:00 Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada THOMSON, LAURA I. COPLAND, LUKE 2017 http://dx.doi.org/10.1017/jog.2017.3 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301700003X en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Journal of Glaciology volume 63, issue 239, page 450-463 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 2017 crcambridgeupr https://doi.org/10.1017/jog.2017.3 2023-05-01T18:21:27Z ABSTRACT Annual and seasonal surface velocities measured continuously from 1960 to 1970 at White Glacier, a 14 km long polythermal valley glacier spanning ~100–1800 m a.s.l., provide the most comprehensive early record of ice dynamics in the Canadian Arctic. Through comparison with differential GPS-derived velocity data spanning 2012–16, we find reductions in mean annual velocity by 31 and 38% at lower elevations (600 and 400 m a.s.l.). These are associated with decreased internal ice deformation due to ice thinning and reduced basal motion likely due to increased hydraulic efficiency in recent years. At higher elevation (~850 m a.s.l.) there is no detectable change in annual velocity and the expected decrease in internal deformation rates due to ice thinning is offset by increased basal motion in both summer and winter, likely attributable to supraglacial melt accessing a still inefficient subglacial drainage system. Decreases in mass flux at lower elevations since the 1960s cannot explain the observed elevation loss of ~20 m, meaning that ice thinning along the glacier trunk is primarily a function of downwasting rather than changing ice dynamics. The current response of the glacier exemplifies steady thinning, velocity slowdown and upstream retreat of the ELA but, because the glacier has an unstable geometry with considerable mass in the 1300–1500 m elevation range, a retreat of the ELA to >1300 plausible within 25–40 years, could trigger runaway wastage. Article in Journal/Newspaper Arctic glacier* Journal of Glaciology Cambridge University Press (via Crossref) Arctic Canada Ela ENVELOPE(9.642,9.642,63.170,63.170) White Glacier ENVELOPE(-90.667,-90.667,79.447,79.447) Journal of Glaciology 63 239 450 463 |
institution |
Open Polar |
collection |
Cambridge University Press (via Crossref) |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes THOMSON, LAURA I. COPLAND, LUKE Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada |
topic_facet |
Earth-Surface Processes |
description |
ABSTRACT Annual and seasonal surface velocities measured continuously from 1960 to 1970 at White Glacier, a 14 km long polythermal valley glacier spanning ~100–1800 m a.s.l., provide the most comprehensive early record of ice dynamics in the Canadian Arctic. Through comparison with differential GPS-derived velocity data spanning 2012–16, we find reductions in mean annual velocity by 31 and 38% at lower elevations (600 and 400 m a.s.l.). These are associated with decreased internal ice deformation due to ice thinning and reduced basal motion likely due to increased hydraulic efficiency in recent years. At higher elevation (~850 m a.s.l.) there is no detectable change in annual velocity and the expected decrease in internal deformation rates due to ice thinning is offset by increased basal motion in both summer and winter, likely attributable to supraglacial melt accessing a still inefficient subglacial drainage system. Decreases in mass flux at lower elevations since the 1960s cannot explain the observed elevation loss of ~20 m, meaning that ice thinning along the glacier trunk is primarily a function of downwasting rather than changing ice dynamics. The current response of the glacier exemplifies steady thinning, velocity slowdown and upstream retreat of the ELA but, because the glacier has an unstable geometry with considerable mass in the 1300–1500 m elevation range, a retreat of the ELA to >1300 plausible within 25–40 years, could trigger runaway wastage. |
format |
Article in Journal/Newspaper |
author |
THOMSON, LAURA I. COPLAND, LUKE |
author_facet |
THOMSON, LAURA I. COPLAND, LUKE |
author_sort |
THOMSON, LAURA I. |
title |
Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada |
title_short |
Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada |
title_full |
Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada |
title_fullStr |
Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada |
title_full_unstemmed |
Multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal White Glacier, Arctic Canada |
title_sort |
multi-decadal reduction in glacier velocities and mechanisms driving deceleration at polythermal white glacier, arctic canada |
publisher |
Cambridge University Press (CUP) |
publishDate |
2017 |
url |
http://dx.doi.org/10.1017/jog.2017.3 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301700003X |
long_lat |
ENVELOPE(9.642,9.642,63.170,63.170) ENVELOPE(-90.667,-90.667,79.447,79.447) |
geographic |
Arctic Canada Ela White Glacier |
geographic_facet |
Arctic Canada Ela White Glacier |
genre |
Arctic glacier* Journal of Glaciology |
genre_facet |
Arctic glacier* Journal of Glaciology |
op_source |
Journal of Glaciology volume 63, issue 239, page 450-463 ISSN 0022-1430 1727-5652 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/jog.2017.3 |
container_title |
Journal of Glaciology |
container_volume |
63 |
container_issue |
239 |
container_start_page |
450 |
op_container_end_page |
463 |
_version_ |
1768382984646295552 |