Centennial‐ and Orbital‐Scale Erosion Beneath the Greenland Ice Sheet Near Jakobshavn Isbræ

Balter-Kennedy, Alexandra; Young, Nicolás E.; Briner, Jason P.; Graham, Brandon L.; Schaefer, Joerg M.

doi:10.1029/2021jf006429

Cited by 6 publications

(1 citation statement)

References 89 publications

(195 reference statements)

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“…These proglacial regions have been studied extensively, and are characterised by dense mapping and numerous geochronological constraints (e.g. Donner & Jungne, 1975;Long et al, 1999;Weidick & Bennike, 2007;Briner et al, 2010;Carlson et al, 2014;Cronauer et al, 2016;Balter-Kennedy et al, 2021). This enables a high density of mid-to-high confidence isochrones to be drawn.…”

Section: Disko Baymentioning

confidence: 99%

A Greenland-wide empirical reconstruction of paleo ice-sheet retreat informed by ice extent markers: PaleoGrIS version 1.0

Leger,

Clark,

Huynh

et al. 2023

Preprint

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Abstract. The Greenland Ice Sheet is a large contributor to global sea-level rise, and current mass losses are projected to accelerate. However, model projections of future ice-sheet evolution are limited by the fact that the ice sheet is not in equilibrium with present-day climate, but is still adjusting to past changes that occurred over thousands of years. Whilst the influence of such committed adjustments on future ice-sheet evolution remains unquantified, it could be addressed by calibrating numerical ice sheet models over larger timescales and, importantly, against empirical data on ice margin positions. To enable such paleo data-model interactions, we need Greenland-wide empirical reconstructions of past ice-sheet extent that combine geomorphological and geochronological evidence. Despite an increasing number of field studies producing new chronologies, such a reconstruction is currently lacking in Greenland. Furthermore, a time-slice reconstruction can help: i) answer open questions regarding the rate and pattern of ice margin evolution in Greenland since the glacial maximum, ii) develop a standardised record of empirical data, and iii) identify understudied sites for new field campaigns. Based on these motivations, we here present PaleoGrIS 1.0, the first Greenland-wide isochrone reconstruction of ice-sheet extent evolution through the Late-Glacial and early-to-mid Holocene informed by both geomorphological and geochronological markers. Our isochrones have a temporal resolution of 500 years and span ~7.5 kyr from approximately 14 to 6.5 kyr BP. We here describe the resulting reconstruction of the shrinking ice sheet and conduct a series of ice-sheet wide and regional analyses to quantify retreat rates, areal extent change, and their variability across space and time. During the Late-Glacial and early-to-mid Holocene, we find the Greenland Ice Sheet has lost about one third of its areal extent (0.89 million km2). Between ~14 and ~8.5 kyr BP, it experienced a near constant rate of areal extent loss of 170 ± 27 km2 yr-1. We find the ice-sheet-scale pattern of margin retreat is well correlated to atmospheric and oceanic temperature variations, which implies a high sensitivity of the ice sheet to deglacial warming. However, during the Holocene, we observe inertia in the ice-sheet system that likely caused a centennial to millennial-scale time lag in ice-extent response. At the regional scale, we observe highly heterogeneous deglacial responses in ice-extent evident in both magnitude and rate of retreat. We hypothesise that non-climatic factors, such as the asymmetrical nature of continental shelves and onshore bed topographies, play important roles in determining the regional-to-valley scale dynamics. PaleoGrIS 1.0 is an open-access database designed to be used by both the empirical and numerical modelling communities. It should prove a useful basis for improved future versions of the reconstruction when new geomorphological and geochronological data become available.

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Section: Disko Baymentioning

confidence: 99%

A Greenland-wide empirical reconstruction of paleo ice-sheet retreat informed by ice extent markers: PaleoGrIS version 1.0

Leger,

Clark,

Huynh

et al. 2023

Preprint

View full text Add to dashboard Cite

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Shifting sediment depocenters track ice-margin retreat in Baffin Bay

Okuma,

Titschack,

Weiser

et al. 2024

Commun Earth Environ

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Reconstructing the depositional history of Baffin Bay allows insights into the deglacial retreat of the Laurentide, Innuitian, and Greenland ice sheets from their maximum extent during the Last Glacial Maximum. Here, we present radiocarbon-controlled sedimentation rates from Baffin Bay based on 79 sediment cores to assess spatio-temporal variabilities in sediment deposition since the Last Glacial Maximum. This comprehensive dataset reveals that until ~15,000 years ago the deep basin and slopes were the dominant active sediment depocenters along most margins of Baffin Bay, suggesting prolonged ice-margin stability near the shelf edge, much longer than previously suggested. Between 13,000-11,000 years ago, most depocenters shifted quickly from the slope to the inner shelf, evidencing a very rapid landward ice-sheet retreat. The sedimentation rate-based mean erosion rates (0.17 and 0.08 millimeters/year) derived from the West Greenland Shelf underscore the high erosion capacity of the western Greenland Ice Sheet draining into Baffin Bay.

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A Greenland-wide empirical reconstruction of paleo ice sheet retreat informed by ice extent markers: PaleoGrIS version 1.0

Leger,

Clark,

Huynh

et al. 2024

Clim. Past

View full text Add to dashboard Cite

Abstract. The Greenland Ice Sheet is a large contributor to global sea level rise, and current mass losses are projected to accelerate. However, model projections of future ice sheet evolution are limited by the fact that the ice sheet is not in equilibrium with present-day climate but is still adjusting to past changes that occurred over thousands of years. While the influence of such committed adjustments on future ice sheet evolution remains unquantified, it could be addressed by calibrating numerical ice sheet models over larger timescales and, importantly, against empirical data on ice margin positions. To enable such paleo data–model interactions, we need Greenland-wide empirical reconstructions of past ice sheet extent that combine geomorphological and geochronological evidence. Despite an increasing number of field studies producing new chronologies, such a reconstruction is currently lacking in Greenland. Furthermore, a time slice reconstruction can help to (i) answer open questions regarding the rate and pattern of ice margin evolution in Greenland since the glacial maximum, (ii) develop a standardised record of empirical data, and (iii) identify new sites for future field campaigns. Based on these motivations, we here present PaleoGrIS 1.0, a new Greenland-wide isochrone reconstruction of ice sheet extent evolution through the Late Glacial and early- to mid-Holocene informed by both geomorphological and geochronological markers. Our isochrones have a temporal resolution of 500 years and span ∼ 7.5 kyr from approximately 14 to 6.5 kyr BP. We describe the resulting reconstruction of the shrinking ice sheet and conduct a series of ice-sheet-wide and regional analyses to quantify retreat rates, areal extent change, and their variability across space and time. During the Late Glacial and early- to mid-Holocene, we find the Greenland Ice Sheet has lost about one-third of its areal extent (0.89 million km2). Between ∼ 14 and ∼ 8.5 kyr BP, it experienced a near-constant rate of areal extent loss of 170 ± 27 km2 yr−1. We find that the ice-sheet-scale pattern of margin retreat is well correlated to atmospheric and oceanic temperature variations, which implies a high sensitivity of the ice sheet to deglacial warming. However, during the Holocene, we observe inertia in the ice sheet system that likely caused a centennial- to millennial-scale time lag in ice extent response. At the regional scale, we observe highly heterogeneous deglacial responses in ice extent evident in both the magnitude and rate of retreat. We hypothesise that non-climatic factors, such as the asymmetrical nature of continental shelves and onshore bed topographies, play important roles in determining the regional- to valley-scale dynamics. PaleoGrIS 1.0 is an open-access database designed to be used by both the empirical and numerical modelling communities. It should prove a useful basis for improved future versions of the reconstruction when new geomorphological and geochronological data become available.

show abstract

Centennial‐ and Orbital‐Scale Erosion Beneath the Greenland Ice Sheet Near Jakobshavn Isbræ

Cited by 6 publications

References 89 publications

A Greenland-wide empirical reconstruction of paleo ice-sheet retreat informed by ice extent markers: PaleoGrIS version 1.0

A Greenland-wide empirical reconstruction of paleo ice-sheet retreat informed by ice extent markers: PaleoGrIS version 1.0

Shifting sediment depocenters track ice-margin retreat in Baffin Bay

A Greenland-wide empirical reconstruction of paleo ice sheet retreat informed by ice extent markers: PaleoGrIS version 1.0

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