Key publications
Barnett RL, Bernatchez P, Garneau M, Brain MJ, Charman DJ, Stephenson DB, Haley S, Sanderson N (2018). Supplementary Material to Late Holocene sea-level changes in eastern Québec and potential drivers, Barnett et al. JQSR.
Abstract:
Supplementary Material to Late Holocene sea-level changes in eastern Québec and potential drivers, Barnett et al. JQSR
This dataset contains Supplementary Material linked to the article: "Late Holocene sea-level changes in eastern Québec and potential drivers" by Barnett et al. in the journal of Quaternary Science Reviews. It contains transfer function performance results and data metrics for core SimVII including: sample specific transfer function derived palaeo-marsh surface estimates, age-depth solutions, relative sea level reconstruction solutions, LOI and bulk density measurements, geotechnical property solutions, post-depositional lowering estimates and foraminifera counts.
Abstract.
Full text.
Maezumi SY, Alves D, Robinson M, de Souza JG, Levis C, Barnett RL, Almeida de Oliveira E, Urrego D, Schaan D, Iriarte J, et al (2018). The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon.
Nat Plants,
4(8), 540-547.
Abstract:
The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon.
The legacy of pre-Columbian land use in the Amazonian rainforest is one of the most controversial topics in the social1-10 and natural sciences11,12. Until now, the debate has been limited to discipline-specific studies, based purely on archaeological data8, modern vegetation13, modern ethnographic data3 or a limited integration of archaeological and palaeoecological data12. The lack of integrated studies to connect past land use with modern vegetation has left questions about the legacy of pre-Columbian land use on the modern vegetation composition in the Amazon, unanswered11. Here, we show that persistent anthropogenic landscapes for the past 4,500 years have had an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. We found an abrupt enrichment of edible plant species in fossil lake and terrestrial records associated with pre-Columbian occupation. Our results demonstrate that, through closed-canopy forest enrichment, limited clearing for crop cultivation and low-severity fire management, long-term food security was attained despite climate and social changes. Our results suggest that, in the eastern Amazon, the subsistence basis for the development of complex societies began ~4,500 years ago with the adoption of polyculture agroforestry, combining the cultivation of multiple annual crops with the progressive enrichment of edible forest species and the exploitation of aquatic resources. This subsistence strategy intensified with the later development of Amazonian dark earths, enabling the expansion of maize cultivation to the Belterra Plateau, providing a food production system that sustained growing human populations in the eastern Amazon. Furthermore, these millennial-scale polyculture agroforestry systems have an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. Together, our data provide a long-term example of past anthropogenic land use that can inform management and conservation efforts in modern Amazonian ecosystems.
Abstract.
Author URL.
Full text.
Barnett RL, Bernatchez P, Garneau M, Juneau M-N (2017). Reconstructing late Holocene relative sea-level changes at the Magdalen Islands (Gulf of St. Lawrence, Canada) using multi-proxy analyses. Journal of Quaternary Science, 32(3), 380-395.
Barnett RL, Newton TL, Charman DJ, Roland Gehrels W (2017). Salt-marsh testate amoebae as precise and widespread indicators of sea-level change.
Earth-Science Reviews,
164, 193-207.
Abstract:
Salt-marsh testate amoebae as precise and widespread indicators of sea-level change
© 2016 Elsevier B.V. Salt-marsh sediments are routinely used to reconstruct sea-level changes over past millennia. These reconstructions bridge an important gap between geological and instrumental sea-level records, and provide insights into the role of atmospheric, oceanic, climatic and anthropogenic sea-level drivers, thereby improving understanding of contemporary and future sea-level changes. Salt-marsh foraminifera, diatoms and testate amoebae are three of the proxies capable of accurately reconstructing former sea level over decadal to millennial timescales. Datasets of surface assemblages are collated along elevational gradients to provide modern analogues that can be used to infer former marsh-surface elevations from fossil assemblages. Testate amoebae are the most recently developed proxy and existing studies suggest that they are at least as precise as the two other proxies. This study provides a synthesis of sea-level research using testate amoebae and collates and analyses existing surface datasets of intertidal salt-marsh testate amoebae from sites throughout the North Atlantic. We test the hypothesis that intertidal testate amoebae demonstrate cosmopolitan intertidal zonation across wide geographical areas in a way that is unique to this proxy. Testate amoebae assemblages are harmonised under a unified taxonomy and standardised into a single basin-wide training set suitable for reconstructing sea-level changes from salt-marsh sediments across the North Atlantic. Transfer functions are developed using regression modelling and show comparable performance values to published local training sets of foraminifera, diatoms and testate amoebae. When used to develop recent (last 100 years) sea-level reconstructions for sites in Norway and Quebec, Canada, the testate amoebae-based transfer function demonstrated prediction uncertainties of ± 0.26 m and ± 0.10 m respectively. These uncertainties equate to 10% and 11% of the tidal ranges at each site, which is of comparable precision to other published sea-level reconstructions based on foraminifera or diatoms. There is great scope for further developing intertidal testate amoebae as precise sea-level indicators and their application should be tested at sites beyond the North Atlantic.
Abstract.
Full text.
Barnett RL, Garneau M, Bernatchez P (2016). Salt-marsh sea-level indicators and transfer function development for the Magdalen Islands in the Gulf of St. Lawrence, Canada. Marine Micropaleontology, 122, 13-26.
Barnett RL, Gehrels WR, Charman DJ, Saher MH, Marshall WA (2015). Late Holocene sea-level change in Arctic Norway.
Quaternary Science Reviews,
107, 214-230.
Abstract:
Late Holocene sea-level change in Arctic Norway
© 2014 Elsevier Ltd. Relative sea-level data from the pre-industrial era are required for validating geophysical models of glacio-isostatic adjustment as well as for testing models used to make sea-level predictions based on future climate change scenarios. We present the first late Holocene (past ~3300 years) relative sea-level reconstruction for northwestern Norway based on investigations in South Hinnøya in the Vesterålen - Lofoton archipelago. Sea-level changes are reconstructed from analyses of salt-marsh and estuarine sediments and the micro-organisms (foraminifera and testate amoebae) preserved within. The 'indicative meaning' of the microfauna is established from their modern distributions. Records are dated by radiocarbon, 201Pb, 137Cs and chemostratigraphical analyses. Our results show a continuous relative sea-level decline of 0.7-0.9mmyr-1 for South Hinnøya during the late Holocene. The reconstruction extends the relative sea-level trend recorded by local tide gauge data which is only available for the past ~25 years. Our reconstruction demonstrates that existing models of shoreline elevations and GIA overpredict sea-level positions during the late Holocene. We suggest that models might be adjusted in order to reconcile modelled and reconstructed sea-level changes and ultimately improve understanding of GIA in Fennoscandia.
Abstract.
Publications by category
Journal articles
Dalton AS, Margold M, Stokes CR, Tarasov L, Dyke AS, Adams RS, Allard S, Arends HE, Atkinson N, Attig JW, et al (2020). An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex.
Quaternary Science Reviews,
234Abstract:
An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex
© 2020 Elsevier Ltd the North American Ice Sheet Complex (NAISC; consisting of the Laurentide, Cordilleran and Innuitian ice sheets) was the largest ice mass to repeatedly grow and decay in the Northern Hemisphere during the Quaternary. Understanding its pattern of retreat following the Last Glacial Maximum is critical for studying many facets of the Late Quaternary, including ice sheet behaviour, the evolution of Holocene landscapes, sea level, atmospheric circulation, and the peopling of the Americas. Currently, the most up-to-date and authoritative margin chronology for the entire ice sheet complex is featured in two publications (Geological Survey of Canada Open File 1574 [Dyke et al. 2003]; ‘Quaternary Glaciations – Extent and Chronology, Part II’ [Dyke, 2004]). These often-cited datasets track ice margin recession in 36 time slices spanning 18 ka to 1 ka (all ages in uncalibrated radiocarbon years) using a combination of geomorphology, stratigraphy and radiocarbon dating. However, by virtue of being over 15 years old, the ice margin chronology requires updating to reflect new work and important revisions. This paper updates the aforementioned 36 ice margin maps to reflect new data from regional studies. We also update the original radiocarbon dataset from the 2003/2004 papers with 1541 new ages to reflect work up to and including 2018. A major revision is made to the 18 ka ice margin, where Banks and Eglinton islands (once considered to be glacial refugia) are now shown to be fully glaciated. Our updated 18 ka ice sheet increased in areal extent from 17.81 to 18.37 million km2, which is an increase of 3.1% in spatial coverage of the NAISC at that time. Elsewhere, we also summarize, region-by-region, significant changes to the deglaciation sequence. This paper integrates new information provided by regional experts and radiocarbon data into the deglaciation sequence while maintaining consistency with the original ice margin positions of Dyke et al. (2003) and Dyke (2004) where new information is lacking; this is a pragmatic solution to satisfy the needs of a Quaternary research community that requires up-to-date knowledge of the pattern of ice margin recession of what was once the world's largest ice mass. The 36 updated isochrones are available in PDF and shapefile format, together with a spreadsheet of the expanded radiocarbon dataset (n = 5195 ages) and estimates of uncertainty for each interval.
Abstract.
Full text.
Barnett RL, Charman DJ, Johns C, Ward SL, Bevan A, Bradley SL, Camidge K, Fyfe RM, Gehrels WR, Gehrels MJ, et al (2020). Nonlinear landscape and cultural response to sea-level rise.
Science Advances,
6(45), eabb6376-eabb6376.
Abstract:
Nonlinear landscape and cultural response to sea-level rise
Rising sea levels have been associated with human migration and behavioral shifts throughout prehistory, often with an emphasis on landscape submergence and consequent societal collapse. However, the assumption that future sea-level rise will drive similar adaptive responses is overly simplistic. While the change from land to sea represents a dramatic and permanent shift for preexisting human populations, the process of change is driven by a complex set of physical and cultural processes with long transitional phases of landscape and socioeconomic change. Here, we use reconstructions of prehistoric sea-level rise, paleogeographies, terrestrial landscape change, and human population dynamics to show how the gradual inundation of an island archipelago resulted in decidedly nonlinear landscape and cultural responses to rising sea levels. Interpretation of past and future responses to sea-level change requires a better understanding of local physical and societal contexts to assess plausible human response patterns in the future.
Abstract.
Full text.
Kemp AC, Wright AJ, Edwards RJ, Barnett RL, Brain MJ, Kopp RE, Cahill N, Horton BP, Charman DJ, Hawkes AD, et al (2018). Relative sea-level change in Newfoundland, Canada during the past ∼3000 years.
Quaternary Science Reviews,
201, 89-110.
Abstract:
Relative sea-level change in Newfoundland, Canada during the past ∼3000 years
© 2018 Elsevier Ltd Several processes contributing to coastal relative sea-level (RSL) change in the North Atlantic Ocean are observed and/or predicted to have distinctive spatial expressions that vary by latitude. To expand the latitudinal range of RSL records spanning the past ∼3000 years and the likelihood of recognizing the characteristic fingerprints of these processes, we reconstructed RSL at two sites (Big River and Placentia) in Newfoundland from salt-marsh sediment. Bayesian transfer functions established the height of former sea level from preserved assemblages of foraminifera and testate amoebae. Age-depth models constrained by radiocarbon dates and chronohorizons estimated the timing of sediment deposition. During the past ∼3000 years, RSL rose by ∼3.0 m at Big River and by ∼1.5 m at Placentia. A locally calibrated geotechnical model showed that post-depositional lowering through sediment compaction was minimal. To isolate and quantify contributions to RSL from global, regional linear, regional non-linear, and local-scale processes, we decomposed the new reconstructions (and those in an expanded, global database) using a spatio-temporal statistical model. The global component confirms that 20th century sea-level rise occurred at the fastest, century-scale rate in over 3000 years (P > 0.999). Distinguishing the contributions from local and regional non-linear processes is made challenging by a sparse network of reconstructions. However, only a small contribution from local-scale processes is necessary to reconcile RSL reconstructions and modeled RSL trends. We identified three latitudinally-organized groups of sites that share coherent regional non-linear trends and indicate that dynamic redistribution of ocean mass by currents and/or winds was likely an important driver of sea-level change in the North Atlantic Ocean during the past ∼3000 years.
Abstract.
Barnett RL, Bernatchez P, Garneau M, Brain MJ, Charman DJ, Stephenson DB, Haley S, Sanderson N (2018). Supplementary Material to Late Holocene sea-level changes in eastern Québec and potential drivers, Barnett et al. JQSR.
Abstract:
Supplementary Material to Late Holocene sea-level changes in eastern Québec and potential drivers, Barnett et al. JQSR
This dataset contains Supplementary Material linked to the article: "Late Holocene sea-level changes in eastern Québec and potential drivers" by Barnett et al. in the journal of Quaternary Science Reviews. It contains transfer function performance results and data metrics for core SimVII including: sample specific transfer function derived palaeo-marsh surface estimates, age-depth solutions, relative sea level reconstruction solutions, LOI and bulk density measurements, geotechnical property solutions, post-depositional lowering estimates and foraminifera counts.
Abstract.
Full text.
Maezumi SY, Alves D, Robinson M, de Souza JG, Levis C, Barnett RL, Almeida de Oliveira E, Urrego D, Schaan D, Iriarte J, et al (2018). The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon.
Nat Plants,
4(8), 540-547.
Abstract:
The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon.
The legacy of pre-Columbian land use in the Amazonian rainforest is one of the most controversial topics in the social1-10 and natural sciences11,12. Until now, the debate has been limited to discipline-specific studies, based purely on archaeological data8, modern vegetation13, modern ethnographic data3 or a limited integration of archaeological and palaeoecological data12. The lack of integrated studies to connect past land use with modern vegetation has left questions about the legacy of pre-Columbian land use on the modern vegetation composition in the Amazon, unanswered11. Here, we show that persistent anthropogenic landscapes for the past 4,500 years have had an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. We found an abrupt enrichment of edible plant species in fossil lake and terrestrial records associated with pre-Columbian occupation. Our results demonstrate that, through closed-canopy forest enrichment, limited clearing for crop cultivation and low-severity fire management, long-term food security was attained despite climate and social changes. Our results suggest that, in the eastern Amazon, the subsistence basis for the development of complex societies began ~4,500 years ago with the adoption of polyculture agroforestry, combining the cultivation of multiple annual crops with the progressive enrichment of edible forest species and the exploitation of aquatic resources. This subsistence strategy intensified with the later development of Amazonian dark earths, enabling the expansion of maize cultivation to the Belterra Plateau, providing a food production system that sustained growing human populations in the eastern Amazon. Furthermore, these millennial-scale polyculture agroforestry systems have an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. Together, our data provide a long-term example of past anthropogenic land use that can inform management and conservation efforts in modern Amazonian ecosystems.
Abstract.
Author URL.
Full text.
Strachan KL, Hill TR, Finch JM, Barnett RL, Frenzel P (2017). Distribution of Salt-Marsh Foraminifera in Two South African Estuaries and the Application as Sea-Level Indicators.
Journal of Coastal Research,
33(3), 619-619.
Full text.
Barnett RL, Bernatchez P, Garneau M, Juneau M-N (2017). Reconstructing late Holocene relative sea-level changes at the Magdalen Islands (Gulf of St. Lawrence, Canada) using multi-proxy analyses. Journal of Quaternary Science, 32(3), 380-395.
Barnett RL, Newton TL, Charman DJ, Roland Gehrels W (2017). Salt-marsh testate amoebae as precise and widespread indicators of sea-level change.
Earth-Science Reviews,
164, 193-207.
Abstract:
Salt-marsh testate amoebae as precise and widespread indicators of sea-level change
© 2016 Elsevier B.V. Salt-marsh sediments are routinely used to reconstruct sea-level changes over past millennia. These reconstructions bridge an important gap between geological and instrumental sea-level records, and provide insights into the role of atmospheric, oceanic, climatic and anthropogenic sea-level drivers, thereby improving understanding of contemporary and future sea-level changes. Salt-marsh foraminifera, diatoms and testate amoebae are three of the proxies capable of accurately reconstructing former sea level over decadal to millennial timescales. Datasets of surface assemblages are collated along elevational gradients to provide modern analogues that can be used to infer former marsh-surface elevations from fossil assemblages. Testate amoebae are the most recently developed proxy and existing studies suggest that they are at least as precise as the two other proxies. This study provides a synthesis of sea-level research using testate amoebae and collates and analyses existing surface datasets of intertidal salt-marsh testate amoebae from sites throughout the North Atlantic. We test the hypothesis that intertidal testate amoebae demonstrate cosmopolitan intertidal zonation across wide geographical areas in a way that is unique to this proxy. Testate amoebae assemblages are harmonised under a unified taxonomy and standardised into a single basin-wide training set suitable for reconstructing sea-level changes from salt-marsh sediments across the North Atlantic. Transfer functions are developed using regression modelling and show comparable performance values to published local training sets of foraminifera, diatoms and testate amoebae. When used to develop recent (last 100 years) sea-level reconstructions for sites in Norway and Quebec, Canada, the testate amoebae-based transfer function demonstrated prediction uncertainties of ± 0.26 m and ± 0.10 m respectively. These uncertainties equate to 10% and 11% of the tidal ranges at each site, which is of comparable precision to other published sea-level reconstructions based on foraminifera or diatoms. There is great scope for further developing intertidal testate amoebae as precise sea-level indicators and their application should be tested at sites beyond the North Atlantic.
Abstract.
Full text.
Kemp AC, Wright AJ, Barnett RL, Hawkes AD, Charman DJ, Sameshima C, King AN, Mooney HC, Edwards RJ, Horton BP, et al (2017). Utility of salt-marsh foraminifera, testate amoebae and bulk-sediment δ<sup>13</sup>C values as sea-level indicators in Newfoundland, Canada.
Marine Micropaleontology,
130, 43-59.
Abstract:
Utility of salt-marsh foraminifera, testate amoebae and bulk-sediment δ13C values as sea-level indicators in Newfoundland, Canada
© 2016 Elsevier B.V. We investigated the utility of foraminifera, testate amoebae and bulk-sediment δ13C measurements for reconstructing Holocene relative sea level from sequences of salt-marsh sediment in Newfoundland, Canada. Modern, surface sediment was collected along transects from low to supra-tidal elevations in eastern (at Placentia) and western (at Hynes Brook and Big River) Newfoundland. Consistent with previous work, low-diversity assemblages of foraminifera display an almost binary division into a higher salt-marsh assemblage dominated by Jadammina macrescens and Balticammina pseudomacrescens and a lower salt-marsh assemblage comprised of Miliammina fusca. This pattern and composition resembles those identified at other high latitude sites with cool climates and confirms that foraminifera are sea-level indicators. The lowest occurrence of testate amoebae was at approximately mean higher high water. The composition of high salt-marsh testate amoebae assemblages (Centropyxis cassis type, Trinema spp. Tracheleuglypha dentata type, and Euglypha spp.) in Newfoundland was similar to elsewhere in the North Atlantic, but preservation bias favors removal of species with idiosomic tests over those with xenosomic tests. The mixed high salt-marsh plant community in Newfoundland results in bulk surface-sediment δ13C values that are typical of C3 plants, making them indistinguishable from freshwater sediment. Therefore we propose that the utility of this proxy for reconstructing RSL in eastern North America is restricted to the coastline between Chesapeake Bay and southern Nova Scotia. Using a simple, multi-proxy approach to establish that samples in three radiocarbon-dated sediment cores formed between the lowest occurrence of testate amoebae and the highest occurrence of foraminifera, we generated three example late Holocene sea-level index points at Hynes Brook.
Abstract.
Full text.
Barnett RL, Garneau M, Bernatchez P (2016). Salt-marsh sea-level indicators and transfer function development for the Magdalen Islands in the Gulf of St. Lawrence, Canada. Marine Micropaleontology, 122, 13-26.
Didier D, Bernatchez P, Boucher-Brossard G, Lambert A, Fraser C, Barnett R, Van-Wierts S (2015). Coastal Flood Assessment Based on Field Debris Measurements and Wave Runup Empirical Model. Journal of Marine Science and Engineering, 3(3), 560-590.
Strachan KL, Finch JM, Hill TR, Barnett RL, Morris CD, Frenzel P (2015). Environmental controls on the distribution of salt-marsh foraminifera from the southern coastline of South Africa. Journal of Biogeography, 43(5), 887-898.
Barnett RL, Gehrels WR, Charman DJ, Saher MH, Marshall WA (2015). Late Holocene sea-level change in Arctic Norway.
Quaternary Science Reviews,
107, 214-230.
Abstract:
Late Holocene sea-level change in Arctic Norway
© 2014 Elsevier Ltd. Relative sea-level data from the pre-industrial era are required for validating geophysical models of glacio-isostatic adjustment as well as for testing models used to make sea-level predictions based on future climate change scenarios. We present the first late Holocene (past ~3300 years) relative sea-level reconstruction for northwestern Norway based on investigations in South Hinnøya in the Vesterålen - Lofoton archipelago. Sea-level changes are reconstructed from analyses of salt-marsh and estuarine sediments and the micro-organisms (foraminifera and testate amoebae) preserved within. The 'indicative meaning' of the microfauna is established from their modern distributions. Records are dated by radiocarbon, 201Pb, 137Cs and chemostratigraphical analyses. Our results show a continuous relative sea-level decline of 0.7-0.9mmyr-1 for South Hinnøya during the late Holocene. The reconstruction extends the relative sea-level trend recorded by local tide gauge data which is only available for the past ~25 years. Our reconstruction demonstrates that existing models of shoreline elevations and GIA overpredict sea-level positions during the late Holocene. We suggest that models might be adjusted in order to reconcile modelled and reconstructed sea-level changes and ultimately improve understanding of GIA in Fennoscandia.
Abstract.
Strachan KL, Hill TR, Finch JM, Barnett RL (2015). VERTICAL ZONATION OF FORAMINIFERA ASSEMBLAGES IN GALPINS SALT MARSH, SOUTH AFRICA. The Journal of Foraminiferal Research, 45(1), 29-41.
Strachan KL, Finch JM, Hill T, Barnett RL (2014). A late Holocene sea-level curve for the east coast of South Africa. South African Journal of Science, 110(1/2), 1-9.
Barnett RL, Charman DJ, Gehrels WR, Saher MH, Marshall WA (2013). Testate Amoebae as Sea-level Indicators in Northwestern Norway: Developments in Sample Preparation and Analysis.
ACTA PROTOZOOLOGICA,
52(3), 115-128.
Author URL.
Publications by year
2020
Dalton AS, Margold M, Stokes CR, Tarasov L, Dyke AS, Adams RS, Allard S, Arends HE, Atkinson N, Attig JW, et al (2020). An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex.
Quaternary Science Reviews,
234Abstract:
An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex
© 2020 Elsevier Ltd the North American Ice Sheet Complex (NAISC; consisting of the Laurentide, Cordilleran and Innuitian ice sheets) was the largest ice mass to repeatedly grow and decay in the Northern Hemisphere during the Quaternary. Understanding its pattern of retreat following the Last Glacial Maximum is critical for studying many facets of the Late Quaternary, including ice sheet behaviour, the evolution of Holocene landscapes, sea level, atmospheric circulation, and the peopling of the Americas. Currently, the most up-to-date and authoritative margin chronology for the entire ice sheet complex is featured in two publications (Geological Survey of Canada Open File 1574 [Dyke et al. 2003]; ‘Quaternary Glaciations – Extent and Chronology, Part II’ [Dyke, 2004]). These often-cited datasets track ice margin recession in 36 time slices spanning 18 ka to 1 ka (all ages in uncalibrated radiocarbon years) using a combination of geomorphology, stratigraphy and radiocarbon dating. However, by virtue of being over 15 years old, the ice margin chronology requires updating to reflect new work and important revisions. This paper updates the aforementioned 36 ice margin maps to reflect new data from regional studies. We also update the original radiocarbon dataset from the 2003/2004 papers with 1541 new ages to reflect work up to and including 2018. A major revision is made to the 18 ka ice margin, where Banks and Eglinton islands (once considered to be glacial refugia) are now shown to be fully glaciated. Our updated 18 ka ice sheet increased in areal extent from 17.81 to 18.37 million km2, which is an increase of 3.1% in spatial coverage of the NAISC at that time. Elsewhere, we also summarize, region-by-region, significant changes to the deglaciation sequence. This paper integrates new information provided by regional experts and radiocarbon data into the deglaciation sequence while maintaining consistency with the original ice margin positions of Dyke et al. (2003) and Dyke (2004) where new information is lacking; this is a pragmatic solution to satisfy the needs of a Quaternary research community that requires up-to-date knowledge of the pattern of ice margin recession of what was once the world's largest ice mass. The 36 updated isochrones are available in PDF and shapefile format, together with a spreadsheet of the expanded radiocarbon dataset (n = 5195 ages) and estimates of uncertainty for each interval.
Abstract.
Full text.
Barnett R, Charman DJ, Johns C, Ward SL, Bevan A, Bradley SL, Camidge K, Fyfe RM, Gehrels WR, Gehrels MJ, et al (2020). Datasets for: Non-linear landscape and cultural response to sea-level rise.
Abstract:
Datasets for: Non-linear landscape and cultural response to sea-level rise
Rising sea levels have been associated with human migration and behavioral shifts throughout prehistory, often with an emphasis on landscape submergence and consequent societal collapse. However, the assumption that future sea-level rise will drive similar adaptive responses is overly simplistic. Whilst the change from land to sea represents a dramatic and permanent shift for pre-existing human populations, the process of change is driven by a complex set of physical and cultural processes with long transitional phases of landscape and socio-economic change. Here we use reconstructions of prehistoric sea-level rise, paleogeographies, terrestrial landscape change and human population dynamics to show how the gradual inundation of an island archipelago resulted in decidedly non-linear landscape and cultural responses to rising sea-levels. Interpretation of past and future responses to sea-level change requires a better understanding of local physical and societal contexts to assess plausible human response patterns in the future.
Abstract.
Full text.
Barnett RL, Charman DJ, Johns C, Ward SL, Bevan A, Bradley SL, Camidge K, Fyfe RM, Gehrels WR, Gehrels MJ, et al (2020). Nonlinear landscape and cultural response to sea-level rise.
Science Advances,
6(45), eabb6376-eabb6376.
Abstract:
Nonlinear landscape and cultural response to sea-level rise
Rising sea levels have been associated with human migration and behavioral shifts throughout prehistory, often with an emphasis on landscape submergence and consequent societal collapse. However, the assumption that future sea-level rise will drive similar adaptive responses is overly simplistic. While the change from land to sea represents a dramatic and permanent shift for preexisting human populations, the process of change is driven by a complex set of physical and cultural processes with long transitional phases of landscape and socioeconomic change. Here, we use reconstructions of prehistoric sea-level rise, paleogeographies, terrestrial landscape change, and human population dynamics to show how the gradual inundation of an island archipelago resulted in decidedly nonlinear landscape and cultural responses to rising sea levels. Interpretation of past and future responses to sea-level change requires a better understanding of local physical and societal contexts to assess plausible human response patterns in the future.
Abstract.
Full text.
2018
Kemp AC, Wright AJ, Edwards RJ, Barnett RL, Brain MJ, Kopp RE, Cahill N, Horton BP, Charman DJ, Hawkes AD, et al (2018). Relative sea-level change in Newfoundland, Canada during the past ∼3000 years.
Quaternary Science Reviews,
201, 89-110.
Abstract:
Relative sea-level change in Newfoundland, Canada during the past ∼3000 years
© 2018 Elsevier Ltd Several processes contributing to coastal relative sea-level (RSL) change in the North Atlantic Ocean are observed and/or predicted to have distinctive spatial expressions that vary by latitude. To expand the latitudinal range of RSL records spanning the past ∼3000 years and the likelihood of recognizing the characteristic fingerprints of these processes, we reconstructed RSL at two sites (Big River and Placentia) in Newfoundland from salt-marsh sediment. Bayesian transfer functions established the height of former sea level from preserved assemblages of foraminifera and testate amoebae. Age-depth models constrained by radiocarbon dates and chronohorizons estimated the timing of sediment deposition. During the past ∼3000 years, RSL rose by ∼3.0 m at Big River and by ∼1.5 m at Placentia. A locally calibrated geotechnical model showed that post-depositional lowering through sediment compaction was minimal. To isolate and quantify contributions to RSL from global, regional linear, regional non-linear, and local-scale processes, we decomposed the new reconstructions (and those in an expanded, global database) using a spatio-temporal statistical model. The global component confirms that 20th century sea-level rise occurred at the fastest, century-scale rate in over 3000 years (P > 0.999). Distinguishing the contributions from local and regional non-linear processes is made challenging by a sparse network of reconstructions. However, only a small contribution from local-scale processes is necessary to reconcile RSL reconstructions and modeled RSL trends. We identified three latitudinally-organized groups of sites that share coherent regional non-linear trends and indicate that dynamic redistribution of ocean mass by currents and/or winds was likely an important driver of sea-level change in the North Atlantic Ocean during the past ∼3000 years.
Abstract.
Barnett RL, Bernatchez P, Garneau M, Brain MJ, Charman DJ, Stephenson DB, Haley S, Sanderson N (2018). Supplementary Material to Late Holocene sea-level changes in eastern Québec and potential drivers, Barnett et al. JQSR.
Abstract:
Supplementary Material to Late Holocene sea-level changes in eastern Québec and potential drivers, Barnett et al. JQSR
This dataset contains Supplementary Material linked to the article: "Late Holocene sea-level changes in eastern Québec and potential drivers" by Barnett et al. in the journal of Quaternary Science Reviews. It contains transfer function performance results and data metrics for core SimVII including: sample specific transfer function derived palaeo-marsh surface estimates, age-depth solutions, relative sea level reconstruction solutions, LOI and bulk density measurements, geotechnical property solutions, post-depositional lowering estimates and foraminifera counts.
Abstract.
Full text.
Maezumi SY, Alves D, Robinson M, de Souza JG, Levis C, Barnett RL, Almeida de Oliveira E, Urrego D, Schaan D, Iriarte J, et al (2018). The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon.
Nat Plants,
4(8), 540-547.
Abstract:
The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon.
The legacy of pre-Columbian land use in the Amazonian rainforest is one of the most controversial topics in the social1-10 and natural sciences11,12. Until now, the debate has been limited to discipline-specific studies, based purely on archaeological data8, modern vegetation13, modern ethnographic data3 or a limited integration of archaeological and palaeoecological data12. The lack of integrated studies to connect past land use with modern vegetation has left questions about the legacy of pre-Columbian land use on the modern vegetation composition in the Amazon, unanswered11. Here, we show that persistent anthropogenic landscapes for the past 4,500 years have had an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. We found an abrupt enrichment of edible plant species in fossil lake and terrestrial records associated with pre-Columbian occupation. Our results demonstrate that, through closed-canopy forest enrichment, limited clearing for crop cultivation and low-severity fire management, long-term food security was attained despite climate and social changes. Our results suggest that, in the eastern Amazon, the subsistence basis for the development of complex societies began ~4,500 years ago with the adoption of polyculture agroforestry, combining the cultivation of multiple annual crops with the progressive enrichment of edible forest species and the exploitation of aquatic resources. This subsistence strategy intensified with the later development of Amazonian dark earths, enabling the expansion of maize cultivation to the Belterra Plateau, providing a food production system that sustained growing human populations in the eastern Amazon. Furthermore, these millennial-scale polyculture agroforestry systems have an enduring legacy on the hyperdominance of edible plants in modern forests in the eastern Amazon. Together, our data provide a long-term example of past anthropogenic land use that can inform management and conservation efforts in modern Amazonian ecosystems.
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2017
Strachan KL, Hill TR, Finch JM, Barnett RL, Frenzel P (2017). Distribution of Salt-Marsh Foraminifera in Two South African Estuaries and the Application as Sea-Level Indicators.
Journal of Coastal Research,
33(3), 619-619.
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Barnett RL, Bernatchez P, Garneau M, Juneau M-N (2017). Reconstructing late Holocene relative sea-level changes at the Magdalen Islands (Gulf of St. Lawrence, Canada) using multi-proxy analyses. Journal of Quaternary Science, 32(3), 380-395.
Barnett RL, Newton TL, Charman DJ, Roland Gehrels W (2017). Salt-marsh testate amoebae as precise and widespread indicators of sea-level change.
Earth-Science Reviews,
164, 193-207.
Abstract:
Salt-marsh testate amoebae as precise and widespread indicators of sea-level change
© 2016 Elsevier B.V. Salt-marsh sediments are routinely used to reconstruct sea-level changes over past millennia. These reconstructions bridge an important gap between geological and instrumental sea-level records, and provide insights into the role of atmospheric, oceanic, climatic and anthropogenic sea-level drivers, thereby improving understanding of contemporary and future sea-level changes. Salt-marsh foraminifera, diatoms and testate amoebae are three of the proxies capable of accurately reconstructing former sea level over decadal to millennial timescales. Datasets of surface assemblages are collated along elevational gradients to provide modern analogues that can be used to infer former marsh-surface elevations from fossil assemblages. Testate amoebae are the most recently developed proxy and existing studies suggest that they are at least as precise as the two other proxies. This study provides a synthesis of sea-level research using testate amoebae and collates and analyses existing surface datasets of intertidal salt-marsh testate amoebae from sites throughout the North Atlantic. We test the hypothesis that intertidal testate amoebae demonstrate cosmopolitan intertidal zonation across wide geographical areas in a way that is unique to this proxy. Testate amoebae assemblages are harmonised under a unified taxonomy and standardised into a single basin-wide training set suitable for reconstructing sea-level changes from salt-marsh sediments across the North Atlantic. Transfer functions are developed using regression modelling and show comparable performance values to published local training sets of foraminifera, diatoms and testate amoebae. When used to develop recent (last 100 years) sea-level reconstructions for sites in Norway and Quebec, Canada, the testate amoebae-based transfer function demonstrated prediction uncertainties of ± 0.26 m and ± 0.10 m respectively. These uncertainties equate to 10% and 11% of the tidal ranges at each site, which is of comparable precision to other published sea-level reconstructions based on foraminifera or diatoms. There is great scope for further developing intertidal testate amoebae as precise sea-level indicators and their application should be tested at sites beyond the North Atlantic.
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Kemp AC, Wright AJ, Barnett RL, Hawkes AD, Charman DJ, Sameshima C, King AN, Mooney HC, Edwards RJ, Horton BP, et al (2017). Utility of salt-marsh foraminifera, testate amoebae and bulk-sediment δ<sup>13</sup>C values as sea-level indicators in Newfoundland, Canada.
Marine Micropaleontology,
130, 43-59.
Abstract:
Utility of salt-marsh foraminifera, testate amoebae and bulk-sediment δ13C values as sea-level indicators in Newfoundland, Canada
© 2016 Elsevier B.V. We investigated the utility of foraminifera, testate amoebae and bulk-sediment δ13C measurements for reconstructing Holocene relative sea level from sequences of salt-marsh sediment in Newfoundland, Canada. Modern, surface sediment was collected along transects from low to supra-tidal elevations in eastern (at Placentia) and western (at Hynes Brook and Big River) Newfoundland. Consistent with previous work, low-diversity assemblages of foraminifera display an almost binary division into a higher salt-marsh assemblage dominated by Jadammina macrescens and Balticammina pseudomacrescens and a lower salt-marsh assemblage comprised of Miliammina fusca. This pattern and composition resembles those identified at other high latitude sites with cool climates and confirms that foraminifera are sea-level indicators. The lowest occurrence of testate amoebae was at approximately mean higher high water. The composition of high salt-marsh testate amoebae assemblages (Centropyxis cassis type, Trinema spp. Tracheleuglypha dentata type, and Euglypha spp.) in Newfoundland was similar to elsewhere in the North Atlantic, but preservation bias favors removal of species with idiosomic tests over those with xenosomic tests. The mixed high salt-marsh plant community in Newfoundland results in bulk surface-sediment δ13C values that are typical of C3 plants, making them indistinguishable from freshwater sediment. Therefore we propose that the utility of this proxy for reconstructing RSL in eastern North America is restricted to the coastline between Chesapeake Bay and southern Nova Scotia. Using a simple, multi-proxy approach to establish that samples in three radiocarbon-dated sediment cores formed between the lowest occurrence of testate amoebae and the highest occurrence of foraminifera, we generated three example late Holocene sea-level index points at Hynes Brook.
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2016
Barnett RL, Garneau M, Bernatchez P (2016). Salt-marsh sea-level indicators and transfer function development for the Magdalen Islands in the Gulf of St. Lawrence, Canada. Marine Micropaleontology, 122, 13-26.
2015
Didier D, Bernatchez P, Boucher-Brossard G, Lambert A, Fraser C, Barnett R, Van-Wierts S (2015). Coastal Flood Assessment Based on Field Debris Measurements and Wave Runup Empirical Model. Journal of Marine Science and Engineering, 3(3), 560-590.
Strachan KL, Finch JM, Hill TR, Barnett RL, Morris CD, Frenzel P (2015). Environmental controls on the distribution of salt-marsh foraminifera from the southern coastline of South Africa. Journal of Biogeography, 43(5), 887-898.
Barnett RL, Gehrels WR, Charman DJ, Saher MH, Marshall WA (2015). Late Holocene sea-level change in Arctic Norway.
Quaternary Science Reviews,
107, 214-230.
Abstract:
Late Holocene sea-level change in Arctic Norway
© 2014 Elsevier Ltd. Relative sea-level data from the pre-industrial era are required for validating geophysical models of glacio-isostatic adjustment as well as for testing models used to make sea-level predictions based on future climate change scenarios. We present the first late Holocene (past ~3300 years) relative sea-level reconstruction for northwestern Norway based on investigations in South Hinnøya in the Vesterålen - Lofoton archipelago. Sea-level changes are reconstructed from analyses of salt-marsh and estuarine sediments and the micro-organisms (foraminifera and testate amoebae) preserved within. The 'indicative meaning' of the microfauna is established from their modern distributions. Records are dated by radiocarbon, 201Pb, 137Cs and chemostratigraphical analyses. Our results show a continuous relative sea-level decline of 0.7-0.9mmyr-1 for South Hinnøya during the late Holocene. The reconstruction extends the relative sea-level trend recorded by local tide gauge data which is only available for the past ~25 years. Our reconstruction demonstrates that existing models of shoreline elevations and GIA overpredict sea-level positions during the late Holocene. We suggest that models might be adjusted in order to reconcile modelled and reconstructed sea-level changes and ultimately improve understanding of GIA in Fennoscandia.
Abstract.
Strachan KL, Hill TR, Finch JM, Barnett RL (2015). VERTICAL ZONATION OF FORAMINIFERA ASSEMBLAGES IN GALPINS SALT MARSH, SOUTH AFRICA. The Journal of Foraminiferal Research, 45(1), 29-41.
2014
Strachan KL, Finch JM, Hill T, Barnett RL (2014). A late Holocene sea-level curve for the east coast of South Africa. South African Journal of Science, 110(1/2), 1-9.
2013
Barnett RL, Charman DJ, Gehrels WR, Saher MH, Marshall WA (2013). Testate Amoebae as Sea-level Indicators in Northwestern Norway: Developments in Sample Preparation and Analysis.
ACTA PROTOZOOLOGICA,
52(3), 115-128.
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