Glacial Isostatic Adjustment Modelling of the Coast Mountains of British Columbia and Southeastern Alaska

2021 ◽  
Author(s):  
Maximilian Lauch ◽  
Thomas James ◽  
Lucinda Leonard ◽  
Yan Jiang ◽  
Joseph Henton ◽  
...  
Keyword(s):  
British Columbia ◽  
Mass Loss ◽  
Thermal Emission ◽  
Tectonic Setting ◽  
Ice Age ◽  
High Mass ◽  
Cascadia Subduction Zone ◽  
Climate Projections ◽  
Coast Mountains ◽  
Crustal Motion

<p>The Coast Mountains in British Columbia and southeastern Alaska contain around 9040 km<sup>2 </sup>of glaciers and ice fields at present. While these glaciers have followed an overall trend of mass loss since the Little Ice Age (or LIA around 300 years before present), the past decade has seen a significant increase in melting rate that is likely to continue due to the effects of climate change. The region is home to a complex tectonic setting, having proximity to the Queen Charlotte-Fairweather transform plate boundary in the northern region and the Cascadia subduction zone (CSZ) in the southern region, which has an associated active volcanic arc underlying the glaciated area. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) glacier melt data collected between 2000 and 2019 represent a melt rate that is averaged between periods of relatively low mass loss (2000-2009) and high mass loss (2010-2019). As a preliminary test, this average melt rate was assumed to be constant back to the LIA. A history of gridded ice thicknesses was calculated to create an ice loading model for input to a series of forward modelling calculations to determine the crustal response. Predictions of vertical crustal motion are compared to available Global Navigation Satellite System (GNSS) measurements of uplift rate to constrain Earth rheology. The results using this simplified loading model favour a thin lithosphere (around 20-40 km thick) and asthenospheric viscosities on the order of 10<sup>19</sup> Pa s. These values are significantly lower than those of rheological profiles used in extant global GIA models, but are in general agreement with previous GIA modelling of the forearc region of the CSZ. To improve the glacial history model, the Open Global Glacier Model (OGGM), driven by historic climate data and statistically downscaled climate projections, is being employed to create a more accurate loading model and refine our estimates of Earth rheology and regional crustal motion. The best-fitting models will be employed to separate GIA and tectonic components of crustal motion and to generate improved regional sea-level projections.</p>

Glacier fluctuations during the past millennium in Garibaldi Provincial Park, southern Coast Mountains, British Columbia

2007 ◽  
Vol 44 (9) ◽  
pp. 1215-1233 ◽  
Author(s):  
Johannes Koch ◽  
John J Clague ◽  
Gerald D Osborn
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Ice Age ◽  
Southern Coast ◽  
Coast Mountains ◽  
The Past ◽  
Glacier Fluctuations ◽  
Garibaldi Provincial Park ◽  
Provincial Park ◽  
Past Millennium

The Little Ice Age glacier history in Garibaldi Provincial Park (southern Coast Mountains, British Columbia) was reconstructed using geomorphic mapping, radiocarbon ages on fossil wood in glacier forefields, dendrochronology, and lichenometry. The Little Ice Age began in the 11th century. Glaciers reached their first maximum of the past millennium in the 12th century. They were only slightly more extensive than today in the 13th century, but advanced at least twice in the 14th and 15th centuries to near their maximum Little Ice Age positions. Glaciers probably fluctuated around these advanced positions from the 15th century to the beginning of the 18th century. They achieved their greatest extent between A.D. 1690 and 1720. Moraines were deposited at positions beyond present-day ice limits throughout the 19th and early 20th centuries. Glacier fluctuations appear to be synchronous throughout Garibaldi Park. This chronology agrees well with similar records from other mountain ranges and with reconstructed Northern Hemisphere temperature series, indicating global forcing of glacier fluctuations in the past millennium. It also corresponds with sunspot minima, indicating that solar irradiance plays an important role in late Holocene climate change.

Late Holocene glacial activity in Manatee Valley, southern Coast Mountains, British Columbia, Canada

2011 ◽  
Vol 48 (3) ◽  
pp. 603-618 ◽  
Author(s):  
Lindsey Koehler ◽  
Dan J. Smith
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
18Th Century ◽  
Ice Age ◽  
Coast Mountains ◽  
Mountain Glaciers ◽  
Subsequent Episode ◽  
Glacial Expansion ◽  
Insight Into ◽  
Lichen Growth

The dendroglaciologic and lichenometric research methodologies employed in this study provide a perspective of glaciological conditions from 5 ka to present in a remote headwater area of the British Columbia Coast Mountains. Since Holocene ice fronts of four glaciers at this site periodically extended below treeline, previous glacier advances overrode and buried forests beneath till deposits. This study suggests that glaciers were expanding into standing forests at 4.76 and 3.78 ka. Following glacier expansion at 3.78 ka, a period of recession ensued when glaciers withdrew upvalley long enough for the development of deep pedogenic surfaces and the growth of trees exceeding 300 years. Investigations at Beluga and Manatee glaciers benchmark a subsequent episode of significant glacial expansion at 2.42 ka referred to as the “Manatee Advance”. This advance has regional correlatives and is distinguished from the Tiedemann Advance at Manatee Glacier by documentation of substantive ice front retreat between the two episodes. Examination of Little Ice Age (LIA) deposits in the study area allowed for presentation and application of a revised Rhizocarpon spp. lichen growth curve. Lichenometric surveys of lateral moraines associated with Beluga, Manatee, and Oluk glaciers provided limited insight into their early LIA behaviour but record advances during the 15th and 16th centuries. Locally, glaciers achieved their maximum LIA size prior to an early to mid 18th century moraine-building event. This reconstruction of Holocene glacial history offers insights consistent with the emerging record of glacier activity described for other southern British Columbia Coast Mountain glaciers.

Little Ice Age glacial activity in the Mt. Waddington area, British Columbia Coast Mountains, Canada

2003 ◽  
Vol 40 (10) ◽  
pp. 1413-1436 ◽  
Author(s):  
S J Larocque ◽  
D J Smith
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Ice Age ◽  
Climate Forcing ◽  
Medium Size ◽  
Coast Mountains ◽  
Mountain Ranges ◽  
Relative Age ◽  
History Of ◽  
Forcing Mechanisms

The establishment of fourteen Little Ice Age (LIA) glacier chronologies in the Mt. Waddington area led to the development of an extended history of glacial activity in this portion of the southern British Columbia Coast Mountains, Canada. The glaciers were located within four different mountain ranges, and were of varying size and aspect. Dendrochronological and lichenometric techniques were used to provide relative age estimates of moraines formed as glacier termini retreated from advanced positions. Evidence for pre-LIA glacial events is best preserved at Tiedemann Glacier, where the oldest glacial advances date to A.D. 620 and 925–933. Soil-covered and well-vegetated moraines built at Cathedral, Pagoda, and Siva glaciers date to between A.D. 1203 and 1226. Following this event, moraines constructed at Ragnarok, Siva, and Cathedral glaciers in the mid-14th century suggest glaciers in the region underwent a period of downwasting and retreat before readvancing. The majority of moraines recorded in the Mt. Waddington area describe late-LIA glacial events shown to have constructed moraines that date to A.D. 1443–1458, 1506–1524, 1562–1575, 1597–1621, 1657–1660, 1767–1784, 1821–1837, 1871–1900, 1915–1928, and 1942–1946. Over the last 500 years, these moraine-building episodes were shown to occur on average every 65 years and suggest there has been prolonged synchronicity in the glaciological response to persistent climate-forcing mechanisms. Nevertheless, our analysis suggests that local factors, such as aspect and size, play an important role in individual glacial response. Notably, ice termini of medium-size glaciers facing eastwards showed a quicker response to climatically induced mass balance changes.

Late Holocene glacial history of Scimitar Glacier, Mt. Waddington area, British Columbia Coast Mountains, Canada

2013 ◽  
Vol 50 (12) ◽  
pp. 1195-1208 ◽  
Author(s):  
Jessica A. Craig ◽  
Dan J. Smith
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Regional Climate ◽  
Ice Age ◽  
Climate Trends ◽  
Glacier Surface ◽  
Coast Mountains ◽  
Standing Trees ◽  
History Of ◽  
Glacial Expansion

Scimitar Glacier originates below the northeast face of Mt. Waddington in the southern British Columbia Coast Mountains and flows 18 km down valley to calve into a proglacial lake. At several locations, downwasting of the glacier surface has exposed stacked till units separated by wood-bearing horizons in the proximal slopes of lateral moraines flanking the glacier. Historical moraine collapse and erosional breaching has also revealed the remains of standing trees buried in moraine-dammed lake sediments. Radiocarbon and tree-ring dating show that Scimitar Glacier expanded down valley at least three times in the late Holocene. The earliest evidence found for ice expansion indicates Scimitar Glacier was advancing in 3167–2737 cal years BP in association with the regional Tiedemann Advance. Following this advance, the glacier downwasted prior to expanding in 1568–1412 cal years BP during the First Millennial Advance. A final period phase of moraine construction was initiated during late Little Ice Age glacial expansion before A.D. 1742 and extended until at least A.D. 1851, after which Scimitar Glacier began to recede and downwaste. This record is comparable to that recorded at other glaciers in the southern British Columbia Coast Mountains and confirms the long-term relationship between regional climate trends and glacier behaviour in this setting.

The sedimentary record and Neoglacial history of Tide Lake, northwestern British Columbia

1992 ◽  
Vol 29 (11) ◽  
pp. 2383-2396 ◽  
Author(s):  
John J. Clague ◽  
William H. Mathews
Keyword(s):  
Twentieth Century ◽  
British Columbia ◽  
Ice Age ◽  
Second Phase ◽  
Northern Coast ◽  
Coast Mountains ◽  
Fine Sediments ◽  
Early Twentieth Century ◽  
Outburst Floods ◽  
History Of

Tide Lake was the largest glacier-dammed lake in British Columbia before its demise in the early twentieth century. Situated in the northern Coast Mountains, the lake was impounded by Frank Mackie Glacier and its Neoglacial end moraine. A study of Tide Lake has provided information on styles of glaciolacustrine sedimentation and the chronology of the Neoglacial interval.Much of the sediment underlying the floor of Tide Lake was transported by subglacial and proglacial meltwater streams flowing from nearby glaciers. During the last phase of the lake, large subaqueous fans were built in front of Berendon and Frank Mackie glaciers, and deltas formed on the east side of the basin. Rhythmically bedded fine sediments, which cover much of the lake floor but are almost completely lacking on the slopes above, were deposited from underflows originating on deltas and subaqueous fans and by fallout from interflows and overflows.Three major and one minor lake phases are recognized from stratigraphic, geomorphic, radiocarbon, and dendrochronological data: the earliest phase is undated, but older than 3000 BP (1300 B.C.); the second phase has yielded radiocarbon ages of 2600–2700 BP (800–1000 B.C.); a third, minor phase, during which Tide Lake was restricted to the northern part of the basin, began before 1600 BP (A.D. 350–550) and probably ended a few hundred years later; the last phase may have begun as early as 1000 BP (A.D. 1000–1150), peaked in the seventeenth century, and ended in the early twentieth century. During each of the four phases, Tide Lake fluctuated in a complex fashion and at times was empty. The second phase corresponds to a widely recognized middle Neoglacial advance in western North America; the last phase is coincident with the Little Ice Age. Outburst floods from Tide Lake in the nineteenth and early twentieth centuries devastated Bowser River valley as far downstream as Bowser Lake. The last of the floods occurred around A.D. 1930 when the Frank Mackie moraine was breached and the lake emptied for the last time.

scholarly journals Mass balance in the Glacier Bay area of Alaska, USA, and British Columbia, Canada, 1995–2011, using airborne laser altimetry

2013 ◽  
Vol 59 (216) ◽  
pp. 632-648 ◽  
Author(s):  
Austin J. Johnson ◽  
Christopher F. Larsen ◽  
Nathaniel Murphy ◽  
Anthony A. Arendt ◽  
S. Lee Zirnheld
Keyword(s):  
British Columbia ◽  
Mass Loss ◽  
Mass Balance ◽  
Mass Loss Rate ◽  
Ice Age ◽  
Center Line ◽  
Laser Altimetry ◽  
Average Mass ◽  
Glacier Bay ◽  
Airborne Laser

AbstractThe Glacier Bay region of southeast Alaska, USA, and British Columbia, Canada, has undergone major glacier retreat since the Little Ice Age (LIA). We used airborne laser altimetry elevation data acquired between 1995 and 2011 to estimate the mass loss of the Glacier Bay region over four time periods (1995–2000, 2000–05, 2005–09, 2009–11). For each glacier, we extrapolated from center-line profiles to the entire glacier to estimate glacier-wide mass balance, and then averaged these results over the entire region using three difference methods (normalized elevation, area-weighted method and simple average). We found that there was large interannual variability of the mass loss since 1995 compared with the long-term (post-LIA) average. For the full period (1995–2011) the average mass loss was 3.93 ± 0.89 Gt a−1 (0.6 ± 0.1 m w.e. a−1), compared with 17.8 Gt a−1 for the post-LIA (1770–1948) rate. Our mass loss rate is consistent with GRACE gravity signal changes for the 2003–10 period. Our results also show that there is a lower bias due to center-line profiling than was previously found by a digital elevation model difference method.

Tree-ring derived Little Ice Age temperature trends from the central British Columbia Coast Mountains, Canada

2012 ◽  
Vol 78 (3) ◽  
pp. 417-426 ◽  
Author(s):  
Kara J. Pitman ◽  
Dan J. Smith
Keyword(s):  
British Columbia ◽  
Coarse Woody Debris ◽  
Little Ice Age ◽  
Woody Debris ◽  
High Elevation ◽  
Ice Age ◽  
Climatic Fluctuations ◽  
Coast Mountains ◽  
Air Temperature Anomaly ◽  
June July

AbstractMost glaciers in the British Columbia Coast Mountains reached their maximum Holocene extent during the Little Ice Age. Early- and late-Little Ice Age intervals of expansion and retreat fluctuations describe a mass-balance response to changing climates. Although existing dendroclimatic records provide insights into these climatic fluctuations over the last 400 yr, their short durations prohibit evaluation of early-Little Ice Age climate variability. To extend the duration of these records, submerged coarse woody debris salvaged from a high-elevation lake was cross-dated to living chronologies. The resulting chronology provides the opportunity to reconstruct a regional June–July air-temperature anomaly record extending from AD 1225 to 2010. The reconstruction shows that the intervals AD 1350–1420, 1475–1550, 1625–1700 and 1830–1940 characterized distinct periods of below-average June–July temperature followed by periods of above-average temperature. Our reconstruction provides the first annually resolved insights into high-elevation climates spanning the Little Ice Age in this region and indicates that Little Ice Age moraine stabilization corresponds to persistent intervals of warmer-than-average temperatures. We conclude that coarse woody debris submerged in high-elevation lakes has considerable potential for developing lengthy proxy climate records, and we recommend that researchers focus attention on this largely ignored paleoclimatic archive.

Dendroglaciological evidence for Holocene glacial advances in the Todd Icefield area, northern British Columbia Coast Mountains

2008 ◽  
Vol 45 (1) ◽  
pp. 83-98 ◽  
Author(s):  
Scott I Jackson ◽  
Sarah C Laxton ◽  
Dan J Smith
Keyword(s):  
British Columbia ◽  
North America ◽  
Late Holocene ◽  
Ice Age ◽  
Abies Lasiocarpa ◽  
Two Phase ◽  
Increment Core ◽  
Coast Mountains ◽  
First Millennium ◽  
Subfossil Wood

Accelerated glacial recession and downwasting in Pacific North America is exposing land surfaces and features buried by glacial advances that, in many locations, predate the recent Little Ice Age (LIA). Dendrochronologic analyses of increment core samples from living trees (Abies lasiocarpa, Tsuga mertensiana) and samples of subfossil wood collected in the Todd Icefield area, Boundary Ranges, British Columbia Coast Mountains, provide the basis for a dendroglaciological and radiocarbon-based reconstruction of late Holocene glacier activity. Five intervals of glacier expansion were recorded by trees killed or buried by advancing glaciers: (1) an advance prior to ~3000 14C years BP; (2) an advance at ~3000 14C years BP that coincides with the regional Tiedemann advance; (3) an unattributed advance at 2300 14C years BP; (4) a two-phase advance at ~1700 and ~1450 14C years BP that corresponds with the regional First Millennium advance; (5) an advance with three phases of expansion that began prior to ~750 14C BP and is consistent with the regional early LIA interval and a two-phase interval of late LIA expansion culminating after ~240 and 100 years BP. This chronology of late Holocene glaciation matches that emerging from similar investigations in the coastal cordillera of Pacific North America and provides additional support for the regional significance of both the Tiedemann and the First Millennium advances.

scholarly journals Holocene glacier history of Frank Mackie Glacier, northern British Columbia Coast Mountains

2017 ◽  
Vol 54 (1) ◽  
pp. 76-87 ◽  
Author(s):  
Vikki M. St-Hilaire ◽  
Dan J. Smith
Keyword(s):  
British Columbia ◽  
Mass Balance ◽  
Little Ice Age ◽  
Radiocarbon Dating ◽  
Ice Age ◽  
Coast Mountains ◽  
The Holocene ◽  
History Of ◽  
Glacier Advance

Frank Mackie Glacier repeatedly advanced across the Bowser River valley in northwestern British Columbia to impound Tide Lake during the Holocene. The most recent infilling of Tide Lake was associated with a late Little Ice Age glacier advance and ended around 1930 when the lake catastrophically drained. Over the last century Frank Mackie Glacier has retreated and down wasted to reveal multiple glaciogenic sedimentary units within the proximal faces of prominent lateral moraines. The units are separated by buried in-situ tree stumps and laterally contiguous wood mats deposited on paleosols. Dendroglaciological and radiocarbon dating of these wood remains show that Frank Mackie Glacier expanded into standing forests at 3710–3300, 2700–2200, 1700–1290, 900–500, and 250–100 cal. years BP. These advances coincide closely in time with the previously established Tide Lake glacier dam chronology and with the Holocene history of other glaciers in the Bowser River watershed. The findings emphasize the likelihood that most glaciers within northwestern British Columbia underwent substantial size and mass balance changes over the last 4000 years, and often spent hundreds of years in advanced positions before retreating.

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