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Distinct moraine complexes are well-preserved at the headwaters of the Requ River valley on the southern slope of Bujia Gangri, the largest center of modern glaciation in the eastern Tanggula Mountains in western China. Dating these moraines is an important step in understanding glacial history, palaeoclimate, and landscape evolution in this region. Surface exposure dating using 10Be was done on twenty-three rock samples from large granitic boulders embedded in moraine crests were collected from the Yongqu River valley and the Daxiong River valley, two glaciated valleys at the headwaters of the Requ River valley. The moraines (M W1 and M E1) closest to the current glaciers in the west (main) and east (hanging) valleys of the Yongqu River valley were dated to 203 ± 51 a (n = 4) and 162 ± 58 a (n = 3); the inner four end moraines (M W3 – 1) and outer ones (M W3 – 2) of the third moraine complex (M W3) in the main valley date to 16.8 ± 1.8 ka (n = 3) and 20.7 ± 1.3 ka (n = 2); end moraines (M E2) near the mouth of the east valley and a high lateral moraine (M EL) on its east side date to 18.9 ± 3.0 ka (n = 4); and a high lateral moraine in the Daxiong valley (M DXL) dates to 18.6 ± 1.3 ka (n = 3). The dating results indicate that these moraines were formed during the Little Ice Age (LIA), the Heinrich 1 (H1) event period, and the global Last Glacial Maximum (LGM G). These glacial events are synchronous with those across the Tibetan Plateau (TP) and its surrounding mountains. Combining the palaeoclimatic and palaeoenvironmental proxies in the TP and its surroundings, we infer that the cooling during the LIA, H1, and LGM G was a main control for these glacial advances. • A preliminary 10Be chronological framework since LGM G has been established in the eastern Tanggula Mountains. • Cooling during LIA, Heinrich 1 and LGM G glacial periods is the main determinant for palaeoglacier fluctuations. • A teleconnection between the North Atlantic cooling and palaeoglaciations since LGM G in the TP has been established. [ABSTRACT FROM AUTHOR]

Glacial landforms on Mount Taibai, the main peak of the Qinling Mountains, China, are investigated to improve understanding of Quaternary palaeoclimate evolution in this key region of China's geographical north and south junction. Cosmogenic radionuclide 10Be exposure dating and glacier-climate modeling are used to reconstruct glacier evolution during the last glaciation in the Eryehai Valley, on the slopes of Mount Taibai. Chronological results indicate that the earliest initiation of the Mount Taibai glaciation was earlier than the global Last Glacial Maximum (gLGM). The glacier subsequently advanced further reaching its greatest extent during the gLGM between ∼23.50 ka and 21.76 ka. After this time, the glacier receded rapidly, before disappearing completely between ∼17.9 ka and 17.7 ka. We also analyzed a compilation of 229 recalculated 10Be exposure ages from the mountain ranges on the eastern Tibetan Plateau (TP), as well as in the Jaggang Mountains on the south-central TP, and found that a few mountain ranges on the eastern TP experienced two distinct millennial-scale moraine building events during the gLGM. Using glacier-climate modeling, temperature was calculated to have fallen from between ∼9.0 and 9.4 °C during the gLGM, with precipitation being 60–80% of the present-day value. If precipitation during the rapid retreat of the glacier between ∼21.76 ka and 18.10 ka were to be consistent with present trends, then the temperature would have needed to increase by a total of ∼1.3 °C during this period, with a mean rate of increase of 0.4 °C/ka. Combining our findings with other paleoclimate proxies, we infer that the main reason that there was no further glacial advance after the gLGM on Mount Taibai was the lower altitude of its peak relative to the Equilibrium-line Altitude (ELA). Our results provide the paleoclimatic conditions of the last glaciation in this critical area of China's geographical north and south junction, and deepen the understanding of how the East Asian Summer Monsoon (EASM) influences glaciers on the TP. • New CRN 10Be exposure age results elucidate the glacial evolutionary process since the last glaciation on Mount Taibai. • The earliest initiation of the Mount Taibai glaciation was earlier than the global Last Glacial Maximum. • The East Asian summer monsoonal was an important factor influencing the fluctuations in paleoglaciers of eastern China. • Some mountains on the eastern TP may have experienced two millennial-scale moraine building events during the gLGM. [ABSTRACT FROM AUTHOR]

The study investigates sequential evolution of glacial-landforms in relation to paleo-climate by establishing glacial chronology in Zemu and East-Rathong Glaciers valleys, Sikkim, Eastern Himalaya during the Late-Quaternary. This region is dominated by the Indian summer monsoon, followed by winter rain from the NE-monsoon and Westerlies which influence the glaciers. The study relies on field-based geomorphological mapping and geospatial datasets. The Toe-to-Headwall Altitude Ratio, Toe-to-Summit Altitude Method, and Maximum Elevation of Lateral Moraines methods have been used to calculate the equilibrium line altitudes (ELA) to assess magnitudes of glacial changes over time. OSL dating is used to assess the timing of glacial stages. Additionally, a comparison is made with ELA changes, the distance of moraines from the present glacier snouts, and established glacial chronologies in neighboring areas. The existing landscape depicts the dominant role of the region's present and past glacial processes. The region is also modified by periglacial, paraglacial, and fluvial processes. Four glacial stages have been identified in the region during the late-Quaternary period, contemporaneous to the Last Glacial Maximum, Younger Dryas, Late-Holocene, and Little Ice Age. The first stage (Sikkim-I), marked by dissected trimlines up to ∼16 km downstream, appears to belong to the global Last Glacial Maximum and dated to ∼18.276 ± 0.589 ka with a change of −519.5 m and − 3.4 °C in ELAs and temperature, respectively. The second stage, Sikkim-II is represented by lateral moraines running up to ∼5 km downstream in U-shaped valleys and seems to coincides with the Younger Dryas with ELAs depression of −261.8 m along with a − 1.7 °C drop in temperature. The third Stage (Sikkim-III), marked by small pairs of stable lateral moraines covered with shrubs within ∼3 km downstream, probably belongs to the late Holocene when ELAs and temperature dropped by −177.3 m and − 1.2 °C, respectively. The fourth stage (Sikkim-IV) is notified by a dumped heap of end moraines within ∼2 km downstream, possibly occurred during the LIA with a depression of −72.4 m in ELAs and − 0.5 °C in temperature. These glacial stages are synchronous with the glaciations in the neighboring regions of Thangu in north-Sikkim, Bhutan, and eastern Himalaya syntax. However, the findings of the study differ from the westerly dominated NW Himalayas, broadly. • It is the first study to explore the Late-Quaternary glaciation history in Zemu and East Rathong glacial valleys, Sikkim Himalaya. • Studied glacial valleys have experienced four contemporaneous glacial stages. • OSL date of the first glacial stage coincides with the timing of the global LGM. • The four glacial stages coincide with the LGM, Younger Dryas, Late Holocene, and LIA. [ABSTRACT FROM AUTHOR]

Areas of Quaternary refugia for tree species have been mainly delineated based on fossil records and phylogeography, but niche modelling can provide useful complementary information. Here we use palaeodistribution modelling to test the main hypotheses about the distribution of Castanea sativa in the Last Glacial Maximum (LGM) and the mid-Holocene in Europe. We computed distribution models for current climatic conditions using different methods, and projected them onto three climatic scenarios for the LGM and the mid-Holocene. The projections were validated with pollen and charcoal records. LGM refugia were suggested in the north of the Iberian, Italian and Balkan Peninsulas, and in northern Anatolia. The projections for the mid-Holocene indicated high climatic suitability and geographic expansion of the species range across southern Europe, including some areas where the species is nowadays considered as non-native. In general, our models are consistent with the patterns proposed with pollen and charcoal records, and partially also with phylogeographic information inferred from genetic data, suggesting that the most suitable areas for C. sativa were extended significantly during the mid-Holocene, but declined afterwards and lost connectivity. The projected patterns were compatible with existing palaeobotanical records of C. sativa and provide a spatially-explicit picture of the species past distribution. [ABSTRACT FROM AUTHOR]

Pollen data recovered from the sedimentary record of western Amazonia is still inadequate to fully address climate changes over the Last Glaciation in this region. The present work focuses vegetation dynamics from an area of southwestern Amazonia during the past 42,000 cal yr B.P. based on the integration of previous and new pollen data. Sediment cores were sampled from two sites covered by tropical rainforest in fluvial terraces of the Madeira River, a major southern Amazonian tributary. The results indicated a significant proportion of cold-adapted Andean tree species, represented by Alnus (0–20%), Hedyosmum (1–15%), Podocarpus (0–5%), Illex (1–11%) and Weinmannia (0–1%) at least between > 43,163–42,018 cal yr B.P. and 10,394–10,240 cal yr B.P. During the Holocene, only pollen representative of herbs and modern Amazonian vegetation persisted. The new pollen record confirmed previous documented results that vegetation communities presently restricted to Andean areas at altitudes higher than 2000–3000 m, occupied this region of the Amazonian lowlands close to the onset and probably also during the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]

It is generally assumed that during the global Last Glacial Maximum (gLGM, i.e. 18–24 ka BP) dry climatic conditions in NE Russia inhibited the growth of large ice caps and restricted glaciers to mountain ranges. However, recent evidence has been found to suggest that glacial summers in NE Russia were as warm as at present while glaciers were more extensive than today. As a result, we hypothesize that precipitation must have been relatively high in order to compensate for the high summer temperatures and the resulting glacial ablation. We estimate precipitation abundance by mass balance calculations for the palaeo-glaciers on Kamchatka and in the Kankaren Range using a degree-day-modelling (DDM) approach, and find that precipitation during the gLGM was likely comparable to, or even exceeded, the modern average. We suggest that stronger than present southerly winds over the Northwest Pacific may have accounted for the abundant precipitation. The DDM-results imply that summer temperature, rather than aridity, limited glacier extent in the southern Pacific Sector of NE Russia during the gLGM. [ABSTRACT FROM AUTHOR]

Insular Southeast Asia is of critical importance to global biodiversity, climate, and socioeconomics. Past environmental histories are a crucial factor influencing contemporary patterns and, in this region, fluctuating sea-level and climate change during the Last Glacial Period (LGP) resulted in drastic changes in both land extent and vegetation cover. However, understanding the past environments of this tropical region is hampered by its sheer size and relative lack of traditional continental proxy records, such as lake sediments. To provide further insight into the response of vegetation to the changing environmental conditions, we use the stable carbon isotope composition (δ 13C) of a bat guano sequence from Liang Mbelen Cave in North Sumatra, to determine whether tropical grass (C 4 vegetation) or forest (C 3 vegetation) was present in the area from c. 30 to 10 cal kyr BP. Our results confirm the presence of C 4 vegetation during the LGP; however, we find that the timing of grass expansion was just prior to the Last Glacial Maximum (LGM; 23–19 kyr BP). Comparing Liang Mbelen with the other evidence from across the region, we find a generally consistent pattern of peak tropical grasses often occurring prior to the LGM in Sundaland, with the timing of forest encroachment variable, although beginning at c. 25 cal kyr BP. We find that the timing of the shift from savanna to forest systems in Sundaland is similar to changes in obliquity, likely resulting in a decrease or elimination of the dry season that favoured forest expansion. Understanding past vegetation history will help the management and protection of the fragile and ecologically valuable ecosystems of SE Asia. • The carbon isotope composition of bat guano records changes tropical vegetation. • Tropical vegetation changed over 40,000 yrs. BP in northern Sumatra. • Grasses were abundant prior to the Last Glacial Maximum. • Changes in grass abundance appear to coincide with obliquity throughout Sundaland. [ABSTRACT FROM AUTHOR]

Abstract: Proxy records from high-altitude locations predating the Last Glacial Maximum are rare but could provide invaluable insights into the response of alpine catchments to the rapid climate fluctuations which characterized the last glacial period. Here we present a detrital-rich flowstone record from Entrische Kirche Cave, an inneralpine cave situated close to the accumulation area of the Pleistocene ice-stream network of the European Alps that expanded repeatedly into the lowlands during glacial maxima. U–Th dating of this calcite is challenging due to high detrital Th. However, petrographic and stable isotope analyses in conjunction with associated clastic cave sediments provide useful insights into the climatic boundary conditions during speleothem formation and into the paleoenvironmental processes which operated in the ~2000m-high catchment above the cave. Our data show that millennial-scale temperature fluctuations had a first-order control on the periglacial activity and vegetation in the catchment which strongly influenced the formation and infiltration of detritus into the karst aquifer. The brown laminated and brown dendritic fabrics that compose much of the detrital-rich flowstone succession reflect these environmental processes. The temperature-dependence of periglacial and permafrost processes allows to constrain the amount of cooling relative to the present-day mean annual air temperature that is required to initiate detrital-rich calcite formation in Entrische Kirche Cave, i.e. −2.5°C (minimum) to −6°C (maximum), respectively. White inclusion-poor calcite that is intercalated with the detrital-rich calcite indicates warm (interstadial) conditions and geomorphological stability in the catchment area. One such phase has been U–Th dated to 88.3±6.9ka (i.e. Greenland Interstadial 21 or 22). [Copyright &y& Elsevier]

Abstract: Some researchers have suggested that Phanerozoic land-based ice sheets extended occasionally into the tropical realm. If true, the tropical ocean at those times must have been distinctly colder than at the Last Glacial Maximum (LGM) when northern hemisphere ice sheets did not extend below 38° latitude. Low-latitude ocean temperatures derived from oxygen isotopes of brachiopod shells test this hypothesis by comparing the temperature regime for Paleozoic and early Mesozoic low-latitude settings to the tropical temperature regime of the modern interstadial ocean, and to mean temperatures estimated for the tropical ocean at LGM. A running mean of pH-adjusted brachiopod habitat temperatures (BHTs) shows that Paleozoic low-latitude oceans were, on average, cool to cold relative to the modern interstadial tropical ocean. At times during Pennsylvanian, Serpukhovian, Tournaisian and Ordovician–Silurian glaciations, these tropical seas were indeed significantly colder on average than at the LGM. Ice-sheets within tropical latitudes can be reasonably predicted at those times. Abundant and diverse Paleozoic brachiopod communities reflect these cool tropical oceans, consistent with modern brachiopod ecological preference for colder waters. Amplified Paleozoic temperature oscillations suggest recurring global warming events which episodically drove these cold tropical oceans to temperatures significantly higher than the warmest modern tropical ocean. [Copyright &y& Elsevier]

Abstract: In this paper, we make an inventory of geomorphic remnants of past glaciations, especially glacial stages that occurred just after the Last Glacial Maximum (LGM). More than 35 terrestrial cosmogenic radionuclide (TCR) ages were obtained, providing new chronological benchmarks for defining the transition between the LGM and the Holocene, thus answering some remaining questions in the southern French Alps (upper Durance catchment). TCR ages fit very well with the scenario defined in other parts of the European Alps: two main generations of post-LGM moraines were identified, highlighting a synchronicity of glacial responses during the Younger Dryas and the Preboreal. Indeed, the first generation we identified corresponds to the Younger Dryas period, while the second generation was shaped during the Preboreal period. They suggest that a relatively thick glacier tongue (300m thick) occupied the upper catchment until the end of the Lateglacial period. The glacier tongue disappeared at the very beginning of the Holocene, before a short glacial re-advance during the Preboreal period. This scenario is linked to a very low equilibrium line altitude (ELA) during the Younger Dryas and the Preboreal: located respectively 340 and 150m below the Little Ice Age (LIA) ELA. Collectively, the results highlight a significant west–east gradient in ELA, probably in relation to westerly and northwesterly winds. Finally, the deglaciation pattern in this area is similar to that of the western and northern Alps, and appears significantly different from the patterns found in the inner and eastern Alps (such as the Ubaye and Maritime Alps patterns). [Copyright &y& Elsevier]

Geomorphic reconstructions of the East Antarctic Ice Sheet history across Antarctica suggest diachronous and varying retreat patterns with changing climate. However, little is known of how terrestrial environments responded to these climate changes because the continental ice sheet covered most Antarctic coastal oases during the Last Glacial Maximum (LGM), eliminating terrestrial records. In this study, the environmental history spanning the last 25,400 years was reconstructed using geochronology, lithology, rock magnetism and geochemistry to understand the effect of glacial–deglacial climate variations on surface processes and Mochou Lake ecology. During the last glacial period (25.4 to 18.8 cal. kyr BP), intensified winds and the freeze-thaw action of ice actively weathered the high elevation western catchment that was a dominant sediment source to the lake. The glacial environmental conditions induced a persistent perennial lake ice-cover resulting in anoxia, low sedimentation, primary production and weak brackish conditions. Progressively, as deglacial conditions augmented around 18.8 cal. kyr BP, increased catchment meltwater flow enhanced sediment transport and also transformed the lake into a freshwater basin, although perennial ice-cover still prevailed. Further, the biotic development of the lake began later in the Mid-Holocene as compared to other lakes in the region, wherein the seasonal lake ice cycle and/or ice moat developed. Weak chemical weathering and pedogenesis also commenced in the catchment in response to the warming climate trend. This delayed response to the Holocene warming was possibly due to the local cooling effect of the Dälk Glacier's discharge that also led to sea-ice persistence in the Prydz Bay. This study also provides further evidence that parts of the Larsemann Hills remained free of erosive grounded ice during the LGM and subsequent deglaciation. The Mirror Peninsula, specifically, escaped ice overriding despite being enclosed by the Dälk Glacier, Lake Nella ice lobe and Amery Ice Shelf. [Display omitted] • A multi-proxy record of glacial-deglacial environment change from lake sediments. • The regional weathering changes are due to geomorphic and atmospheric factors. • Variations in lake ice cover across warming phases limited biogenic productivity. [ABSTRACT FROM AUTHOR]

The strong glacial–interglacial similarity between the magnetic susceptibility (MS) of Southern Ocean sediments and Antarctic ice core dust records has often been used to reconstruct Southern Hemisphere atmospheric variability. Although evaluation of various magnetic properties is essential for identifying the magnetic carriers linked to sedimentological variation, detailed magnetic studies are not sufficient in the Scotia Sea. Here we investigate the bulk and particle-size dependent magnetic properties of Scotia Sea sediments over the past ~22 kyr, to determine the main sediment transport mechanism driving bulk magnetic proxies including MS. In bulk sediments, MS is highest during the last glacial period and is accompanied by an increase in the concentration and grain size of ferrimagnetic and antiferromagnetic minerals. For magnetic mineral assemblages, coarse detrital magnetite is dominant. Of three particle-size fractions (>63, 16–63, and <16 μm), the coarse silt fraction (16–63 μm) is responsible for the magnetic properties of bulk glacial sediments. Such dominant contribution of coarse silts rules out a major input of dust, which is expected as finer silt and clay. The silt fraction exhibits a co-varying magnetic mineral concentration with that of the sand fraction (>63 μm) throughout the last deglaciation, indicating a close linkage between their input mechanisms. Thus, the sediment particles ranging from sand to coarse silt, which control the bulk glacial magnetic proxies, are most plausibly transported by iceberg-rafted debris (IRD). As hematite is relatively concentrated in the sand fraction, the hematite contribution in the bulk sediment can highlight IRD-related magnetic signals rather than magnetite. The bulk hematite contribution simultaneously varies with the deglacial influx of coarse IRD particles (>1 mm) in Scotia Sea sediments, although their glacial inconsistency possibly suggests a different IRD input mechanism during the advancement and retreat of the ice sheet. Consequently, the glacial increase in the bulk magnetic concentration indicates vigorous iceberg calving activity in the Scotia Sea and further suggests the coupled cryosphere–atmosphere system. • Glacial MS increases with coarse detrital magnetite enrichment in silts. • Magnetic concentration in sands and silts indicates the same transport mechanism. • IRD input is the most plausible mechanism for glacial magnetic enrichment. • Bulk hematite contribution highlights IRD input signal during the glacial period. [ABSTRACT FROM AUTHOR]