A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and >/=33,500 carbon-14 years before present ((14)C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000(14)C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720(14)C yr B.P., and at the beginning of the Younger Dryas at 11,050 (14)C yr B. P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges.
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http://dx.doi.org/10.1126/science.269.5230.1541 | DOI Listing |
Sci Rep
December 2024
Department of Geology, R R Lalan College, Bhuj, India.
The Great Rann of Kachchh is a sabkha terrain with a thick succession of Quaternary to Late Holocene sediments, deposited during high sea level after the Last Glacial Maxima. Geomorphologically, the Great Rann of Kachchh is subdivided into Bet Zone, Linear Trench Zone, Great Barren Zone, and Banni Plain. The Bet zone is a slightly elevated flat surface comprising a complex network of bets and interbet channels-the geomorphic entities developed as complex interplay of sea level and coseismic tectonic activity during the Holocene.
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November 2024
Alfred Jahn Cold Regions Research Centre, Institute of Geography and Regional Development, University of Wrocław, Wroclaw, Poland.
The Arctic is rapidly losing its sea ice cover while the region warms faster than anywhere else on Earth. As larger areas become ice-free for longer, winds strengthen and interact more with open waters. Ensuing higher waves also increase coastal erosion and flooding, threatening communities and releasing permafrost carbon.
View Article and Find Full Text PDFNPJ Biodivers
September 2024
Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA.
The refugia hypothesis, often used to explain Amazonia's high biodiversity, initially received ample support but has garnered increasing criticism over time. Palynological, phylogenetic, and vegetation model reconstruction studies have been invoked to support the opposing arguments of extensive fragmentation versus a stable Amazonian Forest during Pleistocene glacial maxima. Here, we test the past existence of forest fragments and savanna connectivity by bias-correcting vegetation distributions from a Dynamic Vegetation Model (DVM) driven by paleoclimate simulations for South America during the Last Glacial Maximum (LGM).
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August 2024
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Bremerhaven, Germany.
Reconstructing rainfall variability and moisture sources is a critical aspect to understand past and future hydroclimate dynamics. Here, we use changes in the deuterium content of land-plant leaf waxes from two marine sediment cores located off Chile to reconstruct changes in rainfall amount and variation in moisture sources over the last ~50 ka. The records indicate increased moisture in central Chile during precession maxima, but an obliquity modulation is evident in southern Chile.
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February 2024
School of Archaeology, University of Oxford, Oxford, OX1 3TG, UK.
The timing of the initial peopling of the Americas is unresolved. Because the archaeological record necessitates discussion of human entry from Beringia into southern North America during the last glaciation, addressing this problem routinely involves evaluating environmental parameters then targeting areas suitable for human settlement. Vertebrate remains indicate landscape quality and are a key dataset for assessing coastal migration theories and the viability of coastal routes.
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