scholarly journals South African speleothems reveal influence of high- and lowlatitude forcing over the past 113.5 k.y.

Geology ◽  
2021 ◽  
Author(s):  
Brian Chase ◽  
Chris Harris ◽  
Maarten J. de Wit ◽  
Jan Kramers ◽  
Sean Doel ◽  
...  
Keyword(s):  
South African ◽  
High Latitude ◽  
Austral Summer ◽  
Summer Rainfall ◽  
Last Glacial ◽  
Change Dynamics ◽  
The Past ◽  
Stage 4 ◽  
Insolation Forcing ◽  
The Last Glacial

Variation in δ18O and δ13C values in a speleothem from the Cango Caves in southernmost South Africa enable the construction of coherent regional composite records spanning the past 113,500 yr. Novel for the region in terms of both their length and detail, these records indicate environmental and climatic changes that both are consistent with records from the wider region and show a clear evolution from low- to high-latitude forcing dominance across the last glacial period. Prior to ca. 70 ka, the influence of direct low-latitude insolation forcing is expressed through increases in summer rainfall during austral summer insolation maxima. With the onset of Marine Isotope Stage 4, cooler global conditions and the development of high-latitude ice sheets appear to have supplanted direct insolation forcing as the dominant driver pacing patterns of environmental change, with records from the Southern and Northern Hemisphere tropics exhibiting a positive relationship until after the Last Glacial Maximum. These results highlight the complexity of South African climate change dynamics as a response to changing global boundary conditions and provide a critical reference for regional and global comparisons.

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

High-Latitude Forcing of the South American Summer Monsoon During the Last Glacial

Science ◽  
2012 ◽  
Vol 335 (6068) ◽  
pp. 570-573 ◽  
Author(s):  
L. C. Kanner ◽  
S. J. Burns ◽  
H. Cheng ◽  
R. L. Edwards
Keyword(s):  
Summer Monsoon ◽  
High Latitude ◽  
South American ◽  
The South ◽  
Last Glacial ◽  
The Last Glacial

Climatic Record of the Past 130,000 Years in North Atlantic Deep-Sea Core V23-82: Correlation with the Terrestrial Record

1973 ◽  
Vol 3 (1) ◽  
pp. 110-116 ◽  
Author(s):  
Constance Sancetta ◽  
John Imbrie ◽  
N.G. Kipp
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
Planktonic Foraminifera ◽  
Linear Interpolation ◽  
Stratigraphic Correlation ◽  
Last Glacial ◽  
The Past ◽  
The North ◽  
The North Atlantic ◽  
The Last Glacial

AbstractQuantitative paleo-environmental analyses of planktonic foraminifera in 182 samples covering the past 130,000 years in North Atlantic deep-sea core V23-82 yield time series interpreted in terms of changing surface-water conditions. An absolute chronology is estimated by linear interpolation between levels dated by 14C or by stratigraphic correlation with other radiometrically dated climatic records. Significant events include: (1) rapid warming at 127,000 YBP, marking the start of the penultimate North Atlantic and European interglacial; (2) 124,000 YBP temperature maximum (Eemian); (3) 109,000 YBP cooling, correlated with the beginning of the last European glaciation (Würm), and representing a temporary cooling of the North Atlantic; (4) severe cooling 73,000 YBP, marking the start of the last full glacial regime in the North Atlantic; (5) short warm intervals within the last glacial regime dated at 59,000 YBP, 48,000 YBP, and 31,000 YBP; (6) rapid termination of the last glacial interval at 11,000 YBP; (7) a 6000 YBP hypsi-saline, followed by lowering salinity values presumably associated with decreasing flux of Gulf Stream waters over the core site.

The leaf wax biomarker record of a Namibian salt pan reveals enhanced summer rainfall during the Last Glacial-Interglacial Transition

2020 ◽  
Vol 543 ◽  
pp. 109561
Author(s):  
Lukas Belz ◽  
Irka Schüller ◽  
Achim Wehrmann ◽  
Jürgen Köster ◽  
Heinz Wilkes
Keyword(s):  
Summer Rainfall ◽  
Last Glacial ◽  
Leaf Wax ◽  
Salt Pan ◽  
The Last Glacial

scholarly journals Northern Iberian abrupt climate change dynamics during the last glacial cycle: A view from lacustrine sediments

2012 ◽  
Vol 36 ◽  
pp. 139-153 ◽  
Author(s):  
Ana Moreno ◽  
Penélope González-Sampériz ◽  
Mario Morellón ◽  
Blas L. Valero-Garcés ◽  
William J. Fletcher
Keyword(s):  
Climate Change ◽  
Lacustrine Sediments ◽  
Abrupt Climate Change ◽  
Glacial Cycle ◽  
Last Glacial ◽  
Change Dynamics ◽  
The Last Glacial

scholarly journals Multi-millennial-scale solar activity and its influences on continental tropical climate: empirical evidence of recurrent cosmic and terrestrial patterns

2015 ◽  
Vol 6 (2) ◽  
pp. 1237-1260
Author(s):  
J. Sánchez-Sesma
Keyword(s):  
Solar Activity ◽  
Empirical Evidence ◽  
Tropical Climate ◽  
Solar Oscillations ◽  
Empirical Modelling ◽  
Last Glacial ◽  
The Past ◽  
Astronomical Forcing ◽  
The Last Glacial ◽  
Millennial Scale

Abstract. Solar activity (SA) oscillations over the past millennia are analyzed and extrapolated based on reconstructed solar-related records. Here, simple recurrent models of SA signal are applied and tested. The consequent results strongly suggest: (a) the existence of multi-millennial (~ 9500 years) scale solar oscillations, and (b) their persistence, over at least the last glacial–interglacial cycle. This empirical modelling of solar recurrent oscillations has also provided a consequent multi-millennial-scale experimental forecast, suggesting a solar decreasing trend toward Grand (Super) Minimum conditions for the upcoming period, AD 2050–2250 (AD 3750–4450). Also, a recurrent linear influence of solar variation on continental tropical climate (CTC) has been assessed for the last 20 kyr, and extrapolated for the next centuries. Taking into account the importance of these estimated SA scenarios a comparison is made with other SA forecasts, and their possible associated astronomical forcing and influences on past and future CTC discussed.

scholarly journals Major diversification of caribou shaped by glacial cycles before the Last Glacial Maximum

2020 ◽  
Author(s):  
Rebecca S. Taylor ◽  
Micheline Manseau ◽  
Cornelya F. C. Klütsch ◽  
Jean L. Polfus ◽  
Audrey Steedman ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
High Latitude ◽  
Glacial Maximum ◽  
Effective Population ◽  
Glacial Cycles ◽  
Last Glacial ◽  
Genetic Patterns ◽  
Population Sizes ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractPleistocene glacial cycles influenced the diversification of high-latitude wildlife species through recurrent periods of range contraction, isolation, divergence, and expansion from refugia and subsequent admixture of refugial populations. For many taxa, research has focused on genetic patterns since the Last Glacial Maximum (LGM), however glacial cycles before the LGM likely impacted genomic variation which may influence contemporary genetic patterns. We investigate diversification and the introgressive history of caribou (Rangifer tarandus) in western Canada using 33 high-coverage whole genomes coupled with larger-scale mitochondrial data. Contrary to the well-established paradigm that caribou ecotypes and contemporary genetic diversity arose from two major lineages in separate refugia during the LGM, a Beringian-Eurasian (BEL) and a North American (NAL) lineage, we found that the major diversifications of caribou occurred much earlier at around 110 kya, the start of the last glacial period. Additionally, we found effective population sizes of some caribou reaching ~700,000 to 1,000,000 individuals, one of the highest recorded historical effective population sizes for any mammal species thus far. Mitochondrial analyses dated introgression events prior to the LGM dating to 20-30 kya and even more ancient at 60 kya, coinciding with colder periods with extensive ice coverage, further demonstrating the importance of glacial cycles and events prior to the LGM in shaping demographic history. Reconstructing the origins and differential introgressive history has implications for predictions on species responses under climate change. Our results highlight the need to investigate pre-LGM demographic patterns to fully reconstruct the origin of species diversity, especially for high-latitude species.

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