Interstadial Rise and Younger Dryas Demise of Scotland's Last Ice Fields

Bromley, Gordon; Putnam, Aaron E.; Borns, Harold W.; Lowell, Thomas V.; Sandford, Thomas C.; Barrell, David

doi:10.1002/2018pa003341

Cited by 38 publications

(48 citation statements)

References 117 publications

(182 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results demonstrate that FIS melting during HSs preceded and contributed to the AMOC disruption that led to HEs during both the last and penultimate glacial periods. Enhanced surface melting of the FIS prior to HEs is consistent with summertime warming in Europe during stadials (Schenk et al, 2018;Bromley et al, 2018).…”

Section: Introductionmentioning

confidence: 56%

“…2B; Jonkers and Kučera, 2015), do not preclude heightened seasonality such as increased summer temperatures in the North Atlantic and Europe. High-resolution climate simulations and proxy evidence, including the disintegration of the Scottish ice cap, support the occurrence of warm European summers during the Younger Dryas stadial (Schenk et al, 2018;Bromley et al, 2018). Although increased aridity could partially explain FIS margin retreat and melting via reduced snow accumulation and increased albedo (i.e., "dirty ice") at the FIS surface, such evidence is presently lacking.…”

Section: Enhanced Surface Melting Of the Fis During North Atlantic Stmentioning

confidence: 99%

“…Warm European summers in response to ocean cooling (e.g., Schenk et al, 2018;Bromley et al, 2018) are likely a recurring feature of North Atlantic stadials. During MIS 6, precursor discharge of meltwaters to the North Atlantic ca.…”

Section: Enhanced Surface Melting Of the Fis During North Atlantic Stmentioning

confidence: 99%

See 2 more Smart Citations

Enhanced surface melting of the Fennoscandian Ice Sheet during periods of North Atlantic cooling

Boswell

Toucanne

Pitel-Roudaut

et al. 2019

Geology

View full text Add to dashboard Cite

Heinrich events (HEs) are dramatic episodes of marine-terminating ice discharge and sediment rafting during periods of cold North Atlantic climate. However, the causal chain of events leading to their occurrence is unresolved. Here, we demonstrate that enhanced surface melting of land-terminating margins of the southern Fennoscandian Ice Sheet (FIS) is a recurring feature of Heinrich stadials (HSs), the cold periods during which HEs occur. We use neodymium isotopes to show that the Channel River transported detrital sediments from the interior of eastern Europe to the Bay of Biscay in the northeast Atlantic Ocean at ca. 158-154 ka. Based on similar evidence from the last glacial period, we infer that this interval corresponds to the melting and retreat of the southern FIS margin despite contemporaneous cooling in the North Atlantic and central Europe. The FIS melting episode occurred just prior to a HE, consistent with findings from the more recent HSs 1, 2, and 3. Based on this evidence, we clarify a sequence of events that precedes HEs. Precursor melting of North Atlantic-adjacent ice sheets induces an initial Atlantic meridional overturning circulation (AMOC) slowdown. Atmospheric changes during the resulting HS cause summertime warming in northern Europe that drives enhanced FIS melting. Subsequent meltwater discharge to the North Atlantic further weakens the AMOC and warms the intermediate water masses that contribute to HEs.

show abstract

Section: Introductionmentioning

confidence: 56%

Section: Enhanced Surface Melting Of the Fis During North Atlantic Stmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced surface melting of the Fennoscandian Ice Sheet during periods of North Atlantic cooling

Boswell

Toucanne

Pitel-Roudaut

et al. 2019

Geology

View full text Add to dashboard Cite

show abstract

“…These issues are interlinked with ongoing debate surrounding the timing of the Younger Dryas maximum, which remains unresolved (cf. Golledge et al, 2008;Palmer et al, 2010Palmer et al, , 2012MacLeod et al, 2011;Ballantyne, 2012;Bromley et al, 2014Bromley et al, , 2016Bromley et al, , 2018Small and Fabel, 2016a, b). Although the above analysis is presented based on the use of neutral-type precipitation values, uncertainties regarding the appropriateness of the specific precipitation values shown in Table 6 (i.e.…”

Section: Regional Palaeoclimatic Inferencesmentioning

confidence: 99%

“…The alternative scenario of a Younger Dryas maximum in the early part of the stadial (cf. Bromley et al, 2014Bromley et al, , 2016Bromley et al, , 2018 would imply that glacier mass balance and thus geometry was dominantly influenced by summer precipitation, i.e. a summer precipitation bias (cf.…”

Section: Regional Palaeoclimatic Inferencesmentioning

confidence: 99%

A spatially-restricted Younger Dryas plateau icefield in the Gaick, Scotland: Reconstruction and palaeoclimatic implications

Chandler

Boston

Lukas

2019

Quaternary Science Reviews

View full text Add to dashboard Cite

Considerable research has been conducted in Scotland to reconstruct Younger Dryas glaciers and palaeoclimatic conditions, but our understanding remains incomplete. In this contribution, we examine the Gaick, a dissected plateau that extends over ~520 km 2 in the Central Grampians, Scotland. The extent and style of Younger Dryas glaciation in the Gaick has been repeatedly contested, although a model of extensive plateau icefield glaciation has become generally accepted. This is despite well-documented issues with key elements of the plateau icefield reconstruction. We synthesise the results of recent geomorphological mapping in the Gaick and recognise a distinct morphostratigraphic signature in the upper parts of the western catchments. This differs markedly from sediment-landform associations in other parts of the area, and we argue this provides a strong indication of spatially-restricted Younger Dryas (~12.9-11.7 ka) glaciation in the Gaick. Our interpretation is independently supported by glacierisation threshold analysis, which implies that the eastern Gaick was unable to nourish Younger Dryas ice. We therefore contest the accepted paradigm of extensive Younger Dryas glaciation in this area. Based on the geomorphological evidence and glacier surface profile modelling, we reconstruct a ~42 km 2 plateau icefield that yields an equilibrium line altitude of 751 ± 46 m. Using this value, a sea-level precipitation value of 826 ± 331 mm a-1 is inferred for the Younger Dryas, which suggests considerably drier conditions than at present. Using recalculated glacier-derived precipitation estimates from Scotland, we present regional climate analysis that corroborates arguments for a strong west-east precipitation gradient across Scotland.

show abstract

Pattern, style and timing of British–Irish Ice Sheet advance and retreat over the last 45 000 years: evidence from NW Scotland and the adjacent continental shelf

Bradwell

Fabel

Clark

et al. 2021

J Quaternary Science

View full text Add to dashboard Cite

Predicting the future response of ice sheets to climate warming and rising global sea level is important but difficult. This is especially so when fast‐flowing glaciers or ice streams, buffered by ice shelves, are grounded on beds below sea level. What happens when these ice shelves are removed? And how do the ice stream and the surrounding ice sheet respond to the abruptly altered boundary conditions? To address these questions and others we present new geological, geomorphological, geophysical and geochronological data from the ice‐stream‐dominated NW sector of the last British–Irish Ice Sheet (BIIS). The study area covers around 45 000 km2 of NW Scotland and the surrounding continental shelf. Alongside seabed geomorphological mapping and Quaternary sediment analysis, we use a suite of over 100 new absolute ages (including cosmogenic‐nuclide exposure ages, optically stimulated luminescence ages and radiocarbon dates) collected from onshore and offshore, to build a sector‐wide ice‐sheet reconstruction combining all available evidence with Bayesian chronosequence modelling. Using this information we present a detailed assessment of ice‐sheet advance/retreat history, and the glaciological connections between different areas of the NW BIIS sector, at different times during the last glacial cycle. The results show a highly dynamic, partly marine, partly terrestrial, ice‐sheet sector undergoing large size variations in response to sub‐millennial‐scale climatic (Dansgaard–Oeschger) cycles over the last 45 000 years. Superimposed on these trends we identify internally driven instabilities, operating at higher frequency, conditioned by local topographic factors, tidewater dynamics and glaciological feedbacks during deglaciation. Specifically, our new evidence indicates extensive marine‐terminating ice‐sheet glaciation of the NW BIIS sector during Greenland Stadials 12 to 9 – prior to the main ‘Late Weichselian’ ice‐sheet glaciation. After a period of restricted glaciation, in Greenland Interstadials 8 to 6, we find good evidence for rapid renewed ice‐sheet build‐up in NW Scotland, with the Minch ice‐stream terminus reaching the continental shelf edge in Greenland Stadial 5, perhaps only briefly. Deglaciation of the NW sector took place in numerous stages. Several grounding‐zone wedges and moraines on the mid‐ and inner continental shelf attest to significant stabilizations of the ice‐sheet grounding line, or ice margin, during overall retreat in Greenland Stadials 3 and 2, and to the development of ice shelves. NW Lewis was the first substantial present‐day land area to deglaciate, in the first half of Greenland Stadial 3 at a time of globally reduced sea‐level c. 26 kabp, followed by Cape Wrath at c. 24 kabp. The topographic confinement of the Minch straits probably promoted ice‐shelf development in early Greenland Stadial 2, providing the ice stream with additional support and buffering it somewhat from external drivers. However, c. 20–19 kabp, as the grounding‐line migrated into shoreward deepening water, co...

show abstract

Interstadial Rise and Younger Dryas Demise of Scotland's Last Ice Fields

Cited by 38 publications

References 117 publications

Enhanced surface melting of the Fennoscandian Ice Sheet during periods of North Atlantic cooling

Enhanced surface melting of the Fennoscandian Ice Sheet during periods of North Atlantic cooling

A spatially-restricted Younger Dryas plateau icefield in the Gaick, Scotland: Reconstruction and palaeoclimatic implications

Pattern, style and timing of British–Irish Ice Sheet advance and retreat over the last 45 000 years: evidence from NW Scotland and the adjacent continental shelf

Contact Info

Product

Resources

About