scholarly journals Climate changes recorded by Hani Peat in Northeast China over the past 13.8 cal ka BP

2019 ◽  
Author(s):  
Ge Shi ◽  
Hong Yan ◽  
Wenchao Zhang ◽  
Haobai Fei ◽  
Shuanshuan Cao ◽  
...  
Keyword(s):  
North Atlantic ◽  
Northeast China ◽  
Chemical Weathering ◽  
Climate Changes ◽  
Organic Matter Content ◽  
Organic Content ◽  
Qinghai Lake ◽  
Weathering Index ◽  
The Holocene ◽  
The Past

Abstract. The Hani peatland is one of the few that remain well-preserved in northeast China, which makes it a valuable site for paleoclimate research. Here, two sediment cores, which cover the past 13.8 ka, were collected, and loss on Ignition (LOI550°C) and X-ray Fluorescence Scanning (XRF) were carried out to build organic matter content and Rb/Sr ratio profiles, in order to assess the climate changes and associated East Asian Summer Monsoon (EASM) evolution since the last deglaciation. The results show that organic content and the chemical weathering index increased from the early to mid Holocene, possibly reflecting increased precipitation and an enhanced EASM. During the mid to late Holocene, the organic content and the chemical weathering index values decreased, implying that the EASM weakened. The variations of monsoon intensity during the Holocene derived from the Hani peat are consistent with the EASM reconstructions from the Gonghai, Daihai, Qinghai Lake, Hexiazi Island and the Yulin loess-paleosol section. Thus the Hani and other published EASM records from northern China demonstrate that the evolution of EASM during the Holocene was likely to be dominated by the combination of the influences from changing solar insolation and northern hemisphere ice volumes. In addition, a 0.5–2 ka band filtering analysis of LOI550°C data show that millennial scale climate changes in northeast China were teleconnected with the North Atlantic ice-rafted debris and solar irradiance records, indicating that both North Atlantic climate changes and solar activity probably affected EASM variations.

Centennial to millennial-scale variability of Holocene climate and environmental dynamics in the western Mediterranean (Lake Sidi Ali, Middle Atlas, Morocco)

2021 ◽  
Author(s):  
Johannes Schmidt ◽  
Cathleen Kertscher ◽  
Markus Reichert ◽  
Helen Ballasus ◽  
Birgit Schneider ◽  
...  
Keyword(s):  
North Atlantic ◽  
Climate Changes ◽  
Western Mediterranean ◽  
Future Climate ◽  
Holocene Climate ◽  
The Holocene ◽  
The North ◽  
Middle Atlas ◽  
Environmental Responses

<p>The Western Mediterranean region including the North African desert margin is considered one of the most sensitive areas to future climate changes. In order to refine long-term scenarios for hydrological and environmental responses to future climate changes in this region, it is important to improve our knowledge about past environmental responses to climatic variability at centennial to millennial timescales. During the last two decades, the recovery and compilation of Holocene records from the subtropical North Atlantic and the Mediterranean Sea have improved our knowledge about millennial-scale variability of the Western Mediterranean palaeoclimate. The variabilities appear to affect regional precipitation patterns and environmental systems in the Western Mediterranean, but the timescales, magnitudes and forcing mechanisms remain poorly known. To compare the changes in Holocene climate variability and geomorphological processes across temporal scales, we analysed a 19.63-m long sediment record from Lake Sidi Ali (33°03’ N, 5°00’ W, 2080 m a.s.l.) in the sub-humid Middle Atlas that spans the last 12,000 years (23 pollen-based radiocarbon dates accompanied with <sup>210</sup>Pb results). We use calibrated XRF core scanning records with an annual to sub-decadal resolution to disentangle the complex interplay between climate changes and environmental dynamics during the Holocene. Data exploration techniques and time series analysis (Redfit, Wavelet) revealed long-term changes in lake behaviour. Three main proxy groups were identified (temperature proxies: 2ky, 1ky and 0.7ky cycles; sediment dynamic proxies: 3.5ky, 1.5ky cycles; hydrological proxies: 1.5ky, 1.2ky, 0.17ky cycles). For example, redox sensitive elements Fe and Mn show 1ky cycles and higher values in the Early Holocene and 1.5ky cycles and lower values in the Mid- to Late Holocene. All groups show specific periodicities throughout the Holocene, demonstrating their particular climatic and geomorphological dependencies. Furthermore, we discuss these periodicities relating to global and hemispheric drivers, such as the North Atlantic Oscillation (NAO), El-Niño Southern Oscillation (ENSO), Innertropical Convergence Zone variability (ITCZ) and North Atlantic cold relapses (Bond events).</p>

scholarly journals Glacier response to North Atlantic climate variability during the Holocene

2015 ◽  
Vol 11 (3) ◽  
pp. 2009-2036 ◽  
Author(s):  
N. L. Balascio ◽  
W. J. D'Andrea ◽  
R. S. Bradley
Keyword(s):  
Climate Variability ◽  
20Th Century ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Late Holocene ◽  
North Atlantic Ocean ◽  
The Holocene ◽  
The Past ◽  
Summer Insolation ◽  
Geochemical Parameters

Abstract. Small glaciers and ice caps respond rapidly to climate variations and records of their past extent provide information on the natural envelope of past climate variability. Millennial-scale trends in Holocene glacier size are well documented and correspond with changes in Northern Hemisphere summer insolation. However, there is only sparse and fragmentary evidence for higher frequency variations in glacier size because in many Northern Hemisphere regions glacier advances of the past few hundred years were the most extensive and destroyed the geomorphic evidence of ice growth and retreat during the past several thousand years. Thus, most glacier records have been of limited use for investigating centennial scale climate forcing and feedback mechanisms. Here we report a continuous record of glacier activity for the last 9.5 ka from southeast Greenland, derived from high-resolution measurements on a proglacial lake sediment sequence. Physical and geochemical parameters show that the glaciers responded to previously documented Northern Hemisphere climatic excursions, including the "8.2 ka" cooling event, the Holocene Thermal Maximum, Neoglacial cooling, and 20th Century warming. In addition, the sediments indicate centennial-scale oscillations in glacier size during the late Holocene. Beginning at 4.1 ka, a series of abrupt glacier advances occurred, each lasting ~100 years and followed by a period of retreat, that were superimposed on a gradual trend toward larger glacier size. Thus, while declining summer insolation caused long-term cooling and glacier expansions during the late Holocene, climate system dynamics resulted in repeated episodes of glacier expansion and retreat on multi-decadal to centennial timescales. These episodes coincided with ice rafting events in the North Atlantic Ocean and periods of regional ice cap expansion, which confirms their regional significance and indicates that considerable glacier activity on these timescales is a normal feature of the cryosphere. The data provide a longer-term perspective on the rate of 20th century glacier retreat and indicate that recent anthropogenic-driven warming has already impacted the regional cryosphere in a manner outside the natural range of Holocene variability.

scholarly journals Sedimentary Responses to Climate Changes and Human Activities Over the Past 7400 Years in the Western Sunda Shelf

2021 ◽  
Vol 9 ◽  
Author(s):  
Kaikai Wu ◽  
Xuefa Shi ◽  
Zhanghua Lou ◽  
Bin Wu ◽  
Jingrui Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Human Activities ◽  
Chemical Weathering ◽  
Climate Changes ◽  
Sediment Supply ◽  
Initial Time ◽  
Sunda Shelf ◽  
The Past ◽  
Terrigenous Input ◽  
Erosion Processes

High-resolution records of grain size, major and trace elements, and Sr-Nd isotopes of Core K17 from the western Sunda Shelf were investigated to evaluate the response of weathering and terrigenous input to climatic changes and human activities over the past 7400 years. Sr-Nd isotopic results indicate that the Kelantan River is the main source of sedimentary material in the study core since the mid-Holocene. Chemical weathering levels are represented by the chemical index of alteration (CIA), αAlNa, and K2O/Al2O3 ratios; and geochemical and grain size proxies (including TiO2/CaO, Rb/Sr ratios, and grain size end-member) were used to establish variations of terrigenous input into the study core since 7400 cal yr BP. Based on these records, the evolution of weathering and terrigenous input processes in the western Sunda Shelf can be divided into four stages. During stage 1 (7400–3700 cal yr BP), increasing precipitation and decreasing temperature jointly balanced the relatively stable weathering and terrigenous sediment supply. Dramatically decreasing weathering rates were consistent with less rainfall and lower temperatures during stage 2 (3700–2600 cal yr BP). Heavy rainfall played a more important role than low temperature in controlling weathering and erosion, leading to increasing terrigenous input in stage 3 (2700–1600 cal yr BP). Because of the decoupling between weathering, erosion, and climate in the late Holocene (stage 4, since 1600 cal yr BP), increasing agriculture and related human activities likely dominated weathering and erosion relative to climate changes. Furthermore, the initial time at which human activity overwhelmed natural processes in the southern South China Sea (SCS) is similar to that in the northern SCS. Our results highlight that human activities during the past 1600 years have gradually overwhelmed natural climatic controls on weathering and erosion processes in the western Sunda Shelf.

Luminescence age constraints on the Pleistocene-Holocene transition recorded in loess sequences

2020 ◽  
Author(s):  
Daniela Constantin ◽  
Stefana-Madalina Sacaciu ◽  
Viorica Tecsa ◽  
Anca Avram ◽  
Robert Begy ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
North Atlantic ◽  
Ice Core ◽  
Soil Formation ◽  
Luminescence Dating ◽  
The Holocene ◽  
The Past ◽  
The North ◽  
The North Atlantic ◽  
The Last Glacial

<p>Here we investigate the timing of the last glacial loess - Holocene soil transition recorded in loess-paleosol sequences across the Chinese Loess Plateau, the SE European loess belt and the Central Great Plains, Nebraska, USA by applying comparative luminescence dating techniques on quartz and feldspars. Equivalent dose measurements were carried out using the single-aliquot regenerative-dose (SAR) protocol on silt (4–11 μm) and sand-sized (63–90 μm and coarser fraction when available) quartz. Feldspar infrared stimulated luminescence (IRSL) emitted by 4–11 μm polymineral grains was measured using the post IR-IRSL<sub>290</sub> technique.</p><p>The paleoenvironmental transition from the last glacial loess to the current interglacial soil was characterized using magnetic susceptibility and its frequency dependence. Based on the OSL ages and the threshold of the magnetic signal enhancement the onset of soil formation started around Termination 1 (~17 ka in the North Atlantic) as observed in radiocarbon-dated regional benthic δ<sup>18</sup>O stacks (Stern and Lisiecki, 2014) but before the stratigraphic Pleistocene/Holocene transition dated at 11.7 ka in ice core records (Svensson et al., 2008).</p><p>No major hiatuses in ages are identified in the investigated sites. A change in the sedimentation rate is generally observed at the Pleistocene-Holocene transition and no significant sedimentation change during the Holocene. Sedimentation rates of around 6 cm/ka are determined for the Holocene soil in most of the sites investigated.</p><p>The magnetic susceptibility indicates a gradual increase in pedogenesis after Termination 1 (∼17 ka in the North Atlantic). Based on this, we infer that the upbuilding soil formation prevailed over topdown soil formation during the Pleistocene-Holocene transition in the investigated sites (Roberts, 2008).</p><p> </p><p>References</p><p>Roberts, H.M., 2008. The development and application of luminescence dating to loess deposits: a perspective on the past, present and future. Boreas 37, 483-507.</p><p>Svensson, A., Andersen, K.K., Bigler, M., Clausen, H.B., Dahl-Jensen, D., Davies, S.M., Johnsen, S.J., Muscheler, R., Parrenin, F., Rasmussen, S.O., Röthlisberger, R., Seierstad, I., Steffensen, J.P., Vinther, B.M., 2008.A 60 000 year Greenland stratigraphic ice core chronology. Climate of the Past 4, 47-57.</p><p>Stern, J.V., Lisiecki, L.E., 2014. Termination 1 timing in radiocarbon-dated regional benthic δ18O stacks. Paleoceanography 29, 1127-1142.</p><p> </p><p>This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme ERC-2015-STG (grant agreement No [678106]).</p>

Holocene Interglacial Migrations of Mammals and Other Vettebrates

1972 ◽  
Vol 2 (3) ◽  
pp. 337-340 ◽  
Author(s):  
C.Bertrand Schultz
Keyword(s):  
Great Plains ◽  
Climate Changes ◽  
Blood System ◽  
Cold Climates ◽  
Dasypus Novemcinctus ◽  
The Holocene ◽  
The Past ◽  
The 1950S

The nine-banded armadillos (Dasypus novemcinctus) have been moving northward in the Great Plains region from the late 1800s to the 1950s but now seem to be retreating from their lately acquired northern range. The armadillos have a nontypical homoiothermic blood system which makes them fairly vulnerable to cold climates. Many other adjustments of animal ranges have taken place in the Holocene, even during the past few centuries and evidence indicates that in many cases climate changes played an important role.

scholarly journals Glacier response to North Atlantic climate variability during the Holocene

2015 ◽  
Vol 11 (12) ◽  
pp. 1587-1598 ◽  
Author(s):  
N. L. Balascio ◽  
W. J. D'Andrea ◽  
R. S. Bradley
Keyword(s):  
Climate Variability ◽  
20Th Century ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Late Holocene ◽  
North Atlantic Ocean ◽  
The Holocene ◽  
The Past ◽  
Summer Insolation ◽  
Geochemical Parameters

Abstract. Small glaciers and ice caps respond rapidly to climate variations, and records of their past extent provide information on the natural envelope of past climate variability. Millennial-scale trends in Holocene glacier size are well documented and correspond with changes in Northern Hemisphere summer insolation. However, there is only sparse and fragmentary evidence for higher-frequency variations in glacier size because in many Northern Hemisphere regions glacier advances of the past few hundred years were the most extensive and destroyed the geomorphic evidence of ice growth and retreat during the past several thousand years. Thus, most glacier records have been of limited use for investigating centennial-scale climate forcing and feedback mechanisms. Here we report a continuous record of glacier activity for the last 9.5 ka from southeast Greenland derived from high-resolution measurements on a proglacial lake sediment sequence. Physical and geochemical parameters show that the glaciers responded to previously documented Northern Hemisphere climatic excursions, including the "8.2 ka" cooling event, the Holocene Thermal Maximum, Neoglacial cooling, and 20th century warming. In addition, the sediments indicate centennial-scale oscillations in glacier size during the late Holocene. Beginning at 4.1 ka, a series of abrupt glacier advances occurred, each lasting ~100 years and followed by a period of retreat, that were superimposed on a gradual trend toward larger glacier size. Thus, while declining summer insolation caused long-term cooling and glacier expansion during the late Holocene, climate system dynamics resulted in repeated episodes of glacier expansion and retreat on multi-decadal to centennial timescales. These episodes coincided with ice rafting events in the North Atlantic Ocean and periods of regional ice cap expansion, which confirms their regional significance and indicates that considerable glacier activity on these timescales is a normal feature of the cryosphere. The data provide a longer-term perspective on the rate of 20th century glacier retreat and indicate that recent anthropogenic-driven warming has already impacted the regional cryosphere in a manner outside the natural range of Holocene variability.

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