scholarly journals Late Glacial and Early Holocene human demographic responses to climatic and environmental change in Atlantic Iberia

2020 ◽  
Vol 376 (1816) ◽  
pp. 20190724 ◽  
Author(s):  
T. Rowan McLaughlin ◽  
Magdalena Gómez-Puche ◽  
João Cascalheira ◽  
Nuno Bicho ◽  
Javier Fernández-López de Pablo
Keyword(s):  
Population Growth ◽  
Quantitative Methods ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Early Holocene ◽  
Food Sources ◽  
Resource Base ◽  
Temporal Models ◽  
Spatio Temporal ◽  
Successive Generations

Successive generations of hunter–gatherers of the Late Glacial and Early Holocene in Iberia had to contend with rapidly changing environments and climatic conditions. This constrained their economic resources and capacity for demographic growth. The Atlantic façade of Iberia was occupied throughout these times and witnessed very significant environmental transformations. Archaeology offers a perspective on how past human population ecologies changed in response to this scenario. Archaeological radiocarbon data are used here to reconstruct demographics of the region over the long term. We introduce various quantitative methods that allow us to develop palaeodemographic and spatio-temporal models of population growth and density, and compare our results to independent records of palaeoenvironmental and palaeodietary change, and growth rates derived from skeletal data. Our results demonstrate that late glacial population growth was stifled by the Younger Dryas stadial, but populations grew in size and density during the Early to Middle Holocene transition. This growth was fuelled in part by an increased dependence on marine and estuarine food sources, demonstrating how the environment was linked to demographic change via the resource base, and ultimately the carrying capacity of the environment. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

2019 ◽  
Vol 15 (2) ◽  
pp. 713-733 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
The Past ◽  
Natural Climate

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled δ<sup>2</sup>H-δ<sup>18</sup>O biomarker paleohygrometer, applied to the Lake Gemündener Maar sediments, Western Eifel, Germany

2018 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Vegetation Period ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
Natural Climate

Abstract. The Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in Central Europe during the Late Glacial, are considered crucial for understanding rapid natural climate change in the past. The sediments from Maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from Lake Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf wax-derived lipid biomarkers (n-alkanes C27 and C29) and hemicellulose-derived sugar biomarkers (arabinose), respectively. Both δ2H and δ18O are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. This enables the coupling of the results via a δ2H-δ18O biomarker paleohygrometer approach and allows calculating past relative air humidity values, which is the major advantage of the applied approach. Fundamental was the finding that the isotopic enrichment of leaf water due to evapotranspiration depends mainly on relative humidity. We hence use the coupled δ2H-δ18O biomarker approach to reconstruct the deuterium-excess of leaf water and in turn relative air humidity values corresponding to the vegetation period and daytime (RHdv). Most importantly, the results of the coupled δ2H-δ18O biomarker paleohygrometer approach (i) support a two-phasing of the Younger Dryas, i.e. a relative wet phase (on Allerød level) followed by a drier Younger Dryas ending, (ii) do not corroborate overall drier climatic conditions characterising the Younger Dryas or a two-phasing with regard to a first dry and cold Younger Dryas phase followed by a warmer period along with increasing precipitation amounts, and (iii) suggest that the amplitude of RHdv changes during the Early Holocene was more pronounced compared to the Younger Dryas. One possible driver for the unexpected Lake Gemündener Maar RHdv variations could be the solar activity.

The transition from the Late Glacial to the Early Holocene and its expression in moraine records of the Silvretta Massif

2021 ◽  
Author(s):  
Sandra M. Braumann ◽  
Joerg M. Schaefer ◽  
Stephanie M. Neuhuber ◽  
Markus Fiebig
Keyword(s):  
Roman Empire ◽  
Northern Hemisphere ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Meridional Overturning Circulation ◽  
Early Holocene ◽  
Age Dating ◽  
Ice Age ◽  
Mountain Glaciers ◽  
Exposure Dating

&lt;p&gt;Mountain glaciers and their preserved moraine records provide important insights into periods when climate conditions favored glacier advance or stabilization. Comprehensive mapping of moraines in glacier forefields elucidates the &lt;em&gt;spatial distribution&lt;/em&gt; of former ice margins. Numerical age dating of moraines, in turn, constrains the &lt;em&gt;timing &lt;/em&gt;of moraine formation intervals. A combination of both methods allows reconstructing the evolution of mountain glaciers across time and space and links today&amp;#8217;s alpine geomorphology with climate of the past.&lt;/p&gt;&lt;p&gt;Here, we present glacier reconstructions from two adjacent valleys in the northern Silvretta Massif (Austrian Alps). Both, the Jamtal and the Laraintal, exhibit multiple prominent moraine ridges outboard the Little Ice Age (LIA) moraine and inboard presumable Late Glacial ice margins. By applying &lt;sup&gt;10&lt;/sup&gt;Be surface exposure dating to these moraines, we decipher the response of Silvretta glaciers to the transition from glacial to interglacial climatic conditions.&lt;/p&gt;&lt;p&gt;Pronounced double-ridge structures in lateral and terminal positions outside the LIA moraines were dated and yield landform ages of 11.3 &amp;#177;0.8 kyrs (n=12) and 10.8 &amp;#177;0.8 kyrs (n=9). This age pattern is consistent across both valleys and implies two significant moraine formation intervals during the earliest Holocene that overlap within uncertainties. Additional samples (n=6) were collected along presumable LIA ice margins. Four of them indeed produced LIA ages with three of them suggesting a culmination in the second half of the 18&lt;sup&gt;th&lt;/sup&gt; century CE (mean age: 260 &amp;#177;25 yrs). This result is in good agreement with &lt;sup&gt;10&lt;/sup&gt;Be ages from a recent study at an adjacent site, which indicate a LIA advance around 260 &amp;#177;30 yrs. The remaining two ages coincide with a phase of cooler temperatures and increased precipitation in Europe from the 4&lt;sup&gt;th&lt;/sup&gt; to 6&lt;sup&gt;th&lt;/sup&gt; century, a climate episode, which is often associated with the fall of the Roman Empire and with the migration period in Europe.&lt;/p&gt;&lt;p&gt;We interpret the sets of Early Holocene moraines as evidence of brief cold lapses, which punctuated the general warming trend at the beginning of the Holocene, with the Preboreal Oscillation (PBO; c. 11,300 to 11,150 cal BP) being the most prominent one. Moraine formation intervals during the Early Holocene have been reported in the wider Alpine region and at other places in the northern hemisphere (e.g. North America, Scandinavia, Greenland). Annual mean temperatures certainly differed at each of these places, but synchronous phases of glacier advances or stabilization are recorded across the northern hemisphere during the Early Holocene. We suggest that freshwater input into the Atlantic Ocean caused phases of temporary weakening of the Atlantic Meridional Overturning Circulation (AMOC), which lead to episodes of relative cooling in the northern hemisphere. This cooling phases are preserved in the Early Holocene moraine sets that we mapped and dated in the Silvretta region.&lt;/p&gt;

scholarly journals Late Glacial–Holocene climatic transition record at the Argentinian Andean piedmont between 33 and 34° S

2014 ◽  
Vol 10 (2) ◽  
pp. 863-875 ◽  
Author(s):  
A. E. Mehl ◽  
M. A. Zárate
Keyword(s):  
Late Pleistocene ◽  
Late Quaternary ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Early Holocene ◽  
South American ◽  
Aeolian Deposits ◽  
The Andes ◽  
Climatic Transition ◽  
Flooding Events

Abstract. The Arroyo La Estacada (~ 33°28' S, 69°02' W), eastern Andean piedmont of Argentina, cuts through an extensive piedmont aggradational unit composed of a dominant Late Pleistocene–early Holocene (LP–EH) alluvial sequence that includes several paleosols. One of these paleosols developed affecting the topmost part of likely Late Glacial aeolian deposits aggraded into a floodplain environment by the end of the Late Pleistocene. The paleosol shows variable grade of development along the arroyo outcrops. Organic matter humification, carbonate accumulation and redox processes were the dominant processes associated with paleosol formation. By the early Holocene, when the formation of the paleosol ended, renewed alluvial aggradation and high magnitude flooding events affected the arroyo's floodplain environment. Accordignly, a period of relative landscape stability in the Arroyo La Estacada basin is inferred from the paleosol developed by the LP–EH transition in response to the climatic conditions in the Andes cordillera piedmont after the Late Glacial arid conditions. The analyzed Late Glacial–Holocene alluvial record of the Andean piedmont constitutes a suitable record of the LP–EH climatic transition in the extra-Andean region of Argentina. It is in agreement with regional paleoclimatic evidence along the southern tip of the South American continent, where other pedosedimentary sequences record similar late Quaternary paleoenvironmental changes over both fluvial and interfluvial areas.

Environmental changes in southeastern Amazonia during the last 25,000 yr revealed from a paleoecological record

2012 ◽  
Vol 77 (1) ◽  
pp. 138-148 ◽  
Author(s):  
Barbara Hermanowski ◽  
Marcondes Lima da Costa ◽  
Hermann Behling
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Environmental Changes ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Early Holocene ◽  
Tropical Atlantic ◽  
Inter Tropical Convergence Zone ◽  
Savanna Vegetation ◽  
Dry Seasons

New pollen, micro-charcoal, sediment and mineral analyses of a radiocarbon-dated sediment core from the Serra Sul dos Carajás (southeast Amazonia) indicate changes between drier and wetter climatic conditions during the past 25,000 yr, reflected by fire events, expansion of savanna vegetation and no-analog Amazonian forest communities. A cool and dry last glacial maximum (LGM) and late glacial were followed by a wet phase in the early Holocene lasting for ca. 1200 yr, when tropical forest occurred under stable humid conditions. Subsequently, an increasingly warm, seasonal climate established. The onset of seasonality falls within the early Holocene warm period, with possibly longer dry seasons from 10,200 to 3400 cal yr BP, and an explicitly drier phase from 9000 to 3700 cal yr BP. Modern conditions with shorter dry seasons became established after 3400 cal yr BP. Taken together with paleoenvironmental evidence from elsewhere in the Amazon Basin, the observed changes in late Pleistocene and Holocene vegetation in the Serra Sul dos Carajás likely reflect large-scale shifts in precipitation patterns driven by the latitudinal displacement of the Inter-Tropical Convergence Zone and changes in sea-surface temperatures in the tropical Atlantic.

scholarly journals Pyramidal Framework: Guidance for the Next Generation of GIS Spatial-Temporal Models

2021 ◽  
Vol 10 (3) ◽  
pp. 188
Author(s):  
Cyril Carré ◽  
Younes Hamdani
Keyword(s):  
Conceptual Models ◽  
Future Generations ◽  
Temporal Data ◽  
Temporal Modeling ◽  
Temporal Models ◽  
Gis Data ◽  
Spatio Temporal ◽  
New Interpretation ◽  
Conventional Literature

Over the last decade, innovative computer technologies and the multiplication of geospatial data acquisition solutions have transformed the geographic information systems (GIS) landscape and opened up new opportunities to close the gap between GIS and the dynamics of geographic phenomena. There is a demand to further develop spatio-temporal conceptual models to comprehensively represent the nature of the evolution of geographic objects. The latter involves a set of considerations like those related to managing changes and object identities, modeling possible causal relations, and integrating multiple interpretations. While conventional literature generally presents these concepts separately and rarely approaches them from a holistic perspective, they are in fact interrelated. Therefore, we believe that the semantics of modeling would be improved by considering these concepts jointly. In this work, we propose to represent these interrelationships in the form of a hierarchical pyramidal framework and to further explore this set of concepts. The objective of this framework is to provide a guideline to orient the design of future generations of GIS data models, enabling them to achieve a better representation of available spatio-temporal data. In addition, this framework aims at providing keys for a new interpretation and classification of spatio-temporal conceptual models. This work can be beneficial for researchers, students, and developers interested in advanced spatio-temporal modeling.

scholarly journals Effect of Different Salinity Levels on Population Dynamics and Growth of the Cyclopoid Copepod Oithona nana

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 190
Author(s):  
Fawzy I. Magouz ◽  
Mohamed A. Essa ◽  
Mustafa Matter ◽  
Abdallah Tageldein Mansour ◽  
Ahmed Gaber ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Transition Period ◽  
Salinity Level ◽  
Food Sources ◽  
Cyclopoid Copepod ◽  
Population Composition ◽  
Optimal Salinity ◽  
Marine Copepod ◽  
Salinity Levels

Copepods are one of the most abundant and diverse live food sources for mesopelagic and bathypelagic fishes and crustaceans. They could contribute to the overlap of the transition period from live feed to an artificial weaning diet in marine larvae production. However, the culture conditions still need optimization to provide sufficient production to cover the increasing demand for marine hatcheries. Therefore, the present study investigated the effects of different salinity levels (5, 10, 15, 20, 25, and 30 ppt) on the population growth, growth rate, and population composition (males, females, copepodite, and nauplii ratio) of the marine copepod, Oithona nana. The experiment continued for 15 days, under laboratory-controlled conditions of temperature (27 ± 1 °C), pH (7.7 ± 0.15), and continuous gentle aeration in 30 L glass aquaria. The copepod culture aquaria were supplemented with a mixture of soybean and yeast (0.5 g 10−6 individual−1 24-h−1) as a feed source. The highest significant population growth and population growth rate of O. nana were achieved with a salinity level of 20 ppt. Regarding population composition, O. nana cultured at the salinity level of 20 ppt recorded the highest significant percentages of copepodite and nauplii. The results concluded that copepod, O. nana, is capable of withstanding abrupt changes in the salinity, but there are limits to their tolerance, with an optimal salinity level of 20 ppt. This salinity level achieved the highest population growth and the highest percentages of copepodite and nauplii of marine Copepoda, O. nana.

scholarly journals Spatio-temporal expectile regression models

2019 ◽  
Vol 20 (4) ◽  
pp. 386-409
Author(s):  
Elmar Spiegel ◽  
Thomas Kneib ◽  
Fabian Otto-Sobotka
Keyword(s):  
Tensor Product ◽  
Least Squares Regression ◽  
Expectile Regression ◽  
Specific Distribution ◽  
Weighted Means ◽  
Temporal Models ◽  
Error Terms ◽  
Spatio Temporal ◽  
Set Up ◽  
Main Effects

Spatio-temporal models are becoming increasingly popular in recent regression research. However, they usually rely on the assumption of a specific parametric distribution for the response and/or homoscedastic error terms. In this article, we propose to apply semiparametric expectile regression to model spatio-temporal effects beyond the mean. Besides the removal of the assumption of a specific distribution and homoscedasticity, with expectile regression the whole distribution of the response can be estimated. For the use of expectiles, we interpret them as weighted means and estimate them by established tools of (penalized) least squares regression. The spatio-temporal effect is set up as an interaction between time and space either based on trivariate tensor product P-splines or the tensor product of a Gaussian Markov random field and a univariate P-spline. Importantly, the model can easily be split up into main effects and interactions to facilitate interpretation. The method is presented along the analysis of spatio-temporal variation of temperatures in Germany from 1980 to 2014.

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