The deglaciation of the Americas during the Last Glacial Termination

Palacios, David; Stokes, Chris R.; Phillips, Fred M.; Clague, John J.; Alcalá-Reygosa, Jesús; Andrés, Nuria; Angel, Isandra; Blard, Pierre Henri; Briner, Jason P.; Hall, Brenda L.; Dahms, Dennis; Hein, Andrew S.; Jomelli, Vincent; Mark, Bryan G.; Martini, Mateo A.; Moreno, Patricio I.; Riedel, Jon; Sagredo, Esteban A.; Stansell, Nathan D.; Vázquez-Selem, Lorenzo; Vuille, Mathias; Ward, David B.

doi:10.1016/j.earscirev.2020.103113

Cited by 80 publications

(49 citation statements)

References 531 publications

(934 reference statements)

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“…This is likely due to the successful exploration and colonization of diverse and uncontested niches by early human societies [36,52,57] resulting in typical spread dynamics [56]. At 14.6 kyr BP, the Antarctic Cold Reversal (ACR) began, resulting in colder conditions that were similar to those attributed to the North Atlantic Younger Dryas (YD) stadial [58][59][60][61]. This colder climate was accompanied by glacial advances throughout South America and higher lake levels in the Altiplano, which, based on palynological and glacial geological studies, appear to be a result of precipitation increase over the Altiplano [62,63].…”

Section: Discussionmentioning

confidence: 99%

Directly modelling population dynamics in the South American Arid Diagonal using ¹⁴ C dates

Timpson

Barberena

Thomas

et al. 2020

Phil. Trans. R. Soc. B

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Large anthropogenic 14 C datasets are widely used to generate summed probability distributions (SPDs) as a proxy for past human population levels. However, SPDs are a poor proxy when datasets are small, bearing little relationship to true population dynamics. Instead, more robust inferences can be achieved by directly modelling the population and assessing the model likelihood given the data. We introduce the R package ADMUR which uses a continuous piecewise linear (CPL) model of population change, calculates the model likelihood given a 14 C dataset, estimates credible intervals using Markov chain Monte Carlo, applies a goodness-of-fit test, and uses the Schwarz Criterion to compare CPL models. We demonstrate the efficacy of this method using toy data, showing that spurious dynamics are avoided when sample sizes are small, and true population dynamics are recovered as sample sizes increase. Finally, we use an improved 14 C dataset for the South American Arid Diagonal to compare CPL modelling to current simulation methods, and identify three Holocene phases when population trajectory estimates changed from rapid initial growth of 4.15% per generation to a decline of 0.05% per generation between 10 821 and 7055 yr BP, then gently grew at 0.58% per generation until 2500 yr BP. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

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Section: Discussionmentioning

confidence: 99%

Directly modelling population dynamics in the South American Arid Diagonal using ¹⁴ C dates

Timpson

Barberena

Thomas

et al. 2020

Phil. Trans. R. Soc. B

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“…This advance could be related to the moraines dated close to Bogota (Fig. 1) between 18 000 and 14 500 cal a BP (Palacios et al, 2020), and the hiatus in Fúquene recorded between 15 570 and 12 140 cal BP ( 14 C 13 110-8680; Vélez et al 2003). The HS1 in Frontino (Velásquez-R and Hooghiemstra, 2013) and Belmira (Velásquez, 2013) was initially warm and dry until 16 200 cal a BP (inferred from pollen records), and then turned cold and wet.…”

Section: Climatic Interpretationmentioning

confidence: 94%

“…In the Eastern Cordillera glaciers had their maximum advance during this time reaching 3100 masl on the wet eastern slope and to about 3750 masl on the drier western slope (Helmens, 2011). According to Palacios et al (2020), temperature decreased by about 8°C. In Colombia, the LGM has been reported as dry and cold in sites at lower elevations (relative to Vahos) such as Fúquene (2580 masl) (Bogotá-A et al, 2011) and El Piñal (Behling and Hooghiemstra, 1999), and as humid in the Belmira Paramo (3300 masl) (Velásquez, 2013).…”

Section: Climatic Interpretationmentioning

confidence: 99%

“…The simultaneous occurrence of wet events in Colombia around 14 000-11 000 a BP indicates that overall the BA and YD were wet events. During the BA, Antarctica cooled and the ITCZ moved northwards bringing wet conditions to Central America (Escobar et al, 2012) and northern South America, including Colombia, where precipitation increased by up to 10% (Palacios et al, 2020;Stansell et al, 2010). The YD recorded at most sites in Colombia (except for Fúquene where a possible hiatus is recorded between 12 140 and 9750 cal a BP; Vélez et al, 2003) indicates wet conditions even though during this time the ITCZ was positioned southwards, as suggested by inferred dry climates in Cariaco and the Venezuelan Andes (Peterson and Haug, 2006;Stansell et al 2010), and wetter conditions in the Peruvian Altiplano and the Amazon region (Baker and Fritz, 2015;Cheng et al, 2013) (SI Fig.…”

Section: Climatic Interpretationmentioning

confidence: 99%

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Late Pleistocene–Holocene environmental and climatic history of a freshwater paramo ecosystem in the northern Andes

Patiño

Vélez

Weber

et al. 2020

J Quaternary Science

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This study presents the first multi-proxy palaeoenvironmental and palaeoclimatic history for northern South America based on the palaeolimnological reconstruction of a pond located in a dry paramo at 3570 masl. During the Last Glacial Maximum (LGM), the study area was under glacial conditions, then during global events Heinrich Stadial 1 (HS1), Bølling-Allerød (BA), and the Younger Dryas (YD), the pond expanded, accumulation rates and proxies for erosion reached the highest values, indicative of humid conditions, with maxima in humidity during the BA and YD. Dry conditions and pond desiccation occurred in the Greenlandian-Northgrippian and by 6010 cal a BP the area was transformed into the mire of today. Comparisons with records from other sites in South America indicate that changes in humidity are most likely controlled by the Intertropical Convergence Zone, mainly during the glacial and postglacial, and by changes in the Pacific Ocean, more pronounced after the YD.

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“…Repeated and complex ice-marginal oscillations during deglaciation characterize the retreat dynamics of the adjacent and linked marine-terminating western extension of this ice mass called the Irish Sea Ice Stream (McCabe et al, 1998;Thomas et al, 2004;Thomas and Chiverrell, 2007;McCabe, 2008;Livingstone et al, 2010Livingstone et al, , 2012Smedley et al, 2017aSmedley et al, , 2017bChiverrell et al, 2018). The timing in which many glaciers and ice sheets reached their maximum extent in the last glacial cycle was out of phase, but broadly form a time window 27.5-19 ka termed the 'Last Glacial Maximum' (LGM) (Clark et al, 2009;Hughes et al, 2013;Hughes and Gibbard, 2015;Palacios et al, 2020) that coincides with the time of minimum sea levels (Lambeck and Purcell, 2001;Lambeck et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation

Chiverrell¹,

Thomas²,

Burke³

et al. 2020

Preprint

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<p>Comprehensive mapping and the Briticechrono geochronology provides a reconstruction of the last advance and retreat of the only land-terminating ice lobe of the western British Irish Ice Sheet. The Irish Sea Glacier was fed by ice from Lake District, Irish Sea and Wales, and extended to maximum limits in the English Midlands. During ice retreat after 27 kyrs, a series of reverse bedrock slopes rendered proglacial lakes endemic in the land-system. Not resembling the more extensive definitions of the classical &#8216;Glacial Lake Lapworth&#8217;, these ice contact lakes were smaller time transgressive moraine- and bedrock-dammed basins that evolved with ice marginal retreat. Combining, for the first time on glacial sediments, OSL bleaching profiles for cobbles with single grain and small aliquot OSL measurements on sands, has produced a coherent chronology from these heterogeneously bleached samples, and constrained for the Irish Sea Glacier a post 30ka ice maximum advance, 26.5&#177;1.8ka maximum extent, and 25.3&#177;1.6 to 20.6&#177;2.2ka retreat vacating the region. With retreat of the Irish Sea Glacier an opportunistic Welsh re-advance 19.7&#177;2.5ka took advantage of the vacated space and rode over Irish Sea Glacier moraines. Our geomorphological chronosequence shows a glacial system forced by climate, but mediated by piracy of ice sources shared with the larger and marine terminating Irish Sea Ice Stream to the west. The Irish Sea Glacier underwent changes flow regime and fronting environments driven by stagnation and decline as the primary impetus to advance was diverted. Ultimately, the glacier of the English Midlands display complex uncoupling and realignment during deglaciation and ice margin retreat towards upland hinterlands ~17.8 kyrs (Lake District and Pennines) and asynchronous behaviour as individual adjacent ice lobes became increasingly important in driving the landform record.</p>

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The deglaciation of the Americas during the Last Glacial Termination

Cited by 80 publications

References 531 publications

Directly modelling population dynamics in the South American Arid Diagonal using ¹⁴ C dates

Directly modelling population dynamics in the South American Arid Diagonal using ¹⁴ C dates

Late Pleistocene–Holocene environmental and climatic history of a freshwater paramo ecosystem in the northern Andes

The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation

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The deglaciation of the Americas during the Last Glacial Termination

Cited by 80 publications

References 531 publications

Directly modelling population dynamics in the South American Arid Diagonal using 14 C dates

Directly modelling population dynamics in the South American Arid Diagonal using 14 C dates

Late Pleistocene–Holocene environmental and climatic history of a freshwater paramo ecosystem in the northern Andes

The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation

Contact Info

Product

Resources

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Directly modelling population dynamics in the South American Arid Diagonal using ¹⁴ C dates

Directly modelling population dynamics in the South American Arid Diagonal using ¹⁴ C dates