A paleotemperature reconstruction inferred from subfossil chironomid (non-biting midge) assemblages in a 13-meter, 14,500-yr lake sediment record from a montane forest in the Pacific Northwest is compared to existing quantitative temperature reconstructions from the Pacific Northwest. With updated temperatures, a regional training set was used to develop a midge-based mean July air temperature (MJAT) inference model (r2jack = 0.71, root mean square error of prediction = 1.09°C). The average inferred MJAT varied between 9.4°C and 13.2°C. During the late-glacial period, MJAT ranged between 9.4°C and 10.8°C, and the lowest MJAT (9.4°C) is inferred at ca. 12.7 ka during the Younger Dryas. The transition into the Early Holocene was marked by an increase from 11°C at 11 ka to 12°C at 9.2 ka. Following deposition of the Mazama tephra, chironomid concentration decreased rapidly, and MJAT rose to 12.3°C at ca. 7.6 ka. This change in chironomid assemblage may be due to the direct effects of the tephra on the surface energy balance. The reconstructed temperature did not track decreasing Holocene summer insolation but instead revealed Late Holocene warming, which is similar to a chironomid reconstruction in the eastern Sierra Nevada and a sea-surface temperature reconstruction from northern California.

Throughout the Pleistocene, valley glaciers repeatedly advanced into the forelands of the European Alps. However, the corresponding geological record is highly fragmentary and the regional glaciation history, especially prior to the last glacial maximum, is still poorly documented. We explored the archives of the Lower Aare Valley in the confluence area of the Aare river with Reuss and Limmat, focusing on the overdeepened Gebenstorf-Stilli Trough. In four scientific boreholes, ∼350 m of drill cores were recovered, and complemented with investigations of outcrops and reflection seismics in the nearby glaciofluvial Habsburg-Rinikerfeld Palaeochannel. The integrative interpretation of these data provides new insights into the local landscape evolution: We identified two generations of glacial basin infill in the Gebenstorf-Stilli Trough that are overlain by glaciofluvial gravels, and two distinct glaciofluvial gravel bodies in the neighboring paleochannel. In this specific local setting, gravel petrographic compositions and their statistical analysis prove to be powerful tools to identify inputs from the confluent catchments, to aid in lithostratigraphic classification, and to interpret the depositional and landscape histories. We suggest that it is mainly the penultimate glaciation, characterized by three separate ice advances, that shaped the present-day study area, and whose deposits are preserved in the Middle Pleistocene archives.

Terrestrial proxies of wind direction spanning the last deglaciation suggest easterly winds were present near the Laurentide Ice Sheet margin in the North American midcontinent. However, the existence and spatial extent of such easterly winds have not been investigated with transient paleoclimate model simulations, which could provide improved dynamical context for interpreting the causes of these winds. Here we assess near-surface winds near the retreating southern Laurentide Ice Sheet margin using iTRACE, a transient simulation of deglacial climate from 20–11 ka. Near the south-central margin, simulated near-surface winds are northeasterly to easterly through the deglaciation, due to katabatic flow off the ice sheet and anticyclonic circulation. As the ice sheet retreats and the Laurentide High moves northeastward and weakens, near-surface northeasterly winds weaken. Meltwater fluxes also influence temperature and sea level pressure over the North Atlantic, leading to easterly wind anomalies over eastern to midwestern North America. The agreement between proxy and model wind directions is promising, although simulated easterly to northeasterly winds extend too far south in iTRACE relative to the proxy data. Agreement is also strongest in winter, spring, and fall, suggesting these may have been seasons with greater aeolian activity.

River terraces serve as excellent indicators of the landform evolution of the Guizhou Plateau. This paper presents the results of terrace investigation and optically stimulated luminescence (OSL) dating focused on five sections along the Liujiang River of the southeastern Guizhou Plateau. The OSL ages of the terraces range from 0.21 ± 0.02 to 16.0 ± 1.4 ka for the first terraces (T1) and from 3.5 ± 0.3 to 26.5 ± 3.3 ka for the second terraces (T2), which are much younger than those of other basins on the Guizhou Plateau. These ages, considered in tandem with the results of previous investigations, enhance our understanding of the fluvial landform evolution of the Guizhou Plateau since the Late Pleistocene. On the Guizhou Plateau platform, terraces are considered to be the response of river evolution to tectonic uplift, indicating a relatively slow geomorphic process. In the slope zone, climate change has had a significant impact on the fluvial landform processes, driving the formation of the younger terraces along the Liujiang River. In the platform–slope transition zone, the evolution of terraces was driven by both tectonic uplift and climate change, where the landform processes were dominated by strong headward erosion.

Loess–paleosol outcrops were logged and dated to trace loess cover during the Pleistocene in a low-elevation mountainous area. The exposed successions were a maximum of 15 m thick and stratigraphically fragmentary. Still, results suggest that loess was deposited in all climatically suitable periods within the limits of the dating methods (ca. 400 ka), and probably also beyond this. Luminescence measurements provided numerical ages from ca. 18 ka to ca. 200 ka and minimum ages of up to >267 ka. Loess accumulation was also active during the relatively mild MIS 3. A new occurrence of a well-preserved Quaternary tephra was documented, correlative with the middle Pleistocene Bag Tephra (ca. 340 or 368 ka). The dating of loess successions provided valuable data on geomorphic evolution as well, identifying hydrological changes and constraining a maximum incision and uplift rate of 0.008–0.035 mm/yr for the western part of the area. The low thickness of loess–paleosol successions and the stratigraphic gaps seem to be a consequence of repeated erosion during the Pleistocene rather than a result of non-deposition. The mountains probably have been covered with loess for most of the time during the past 1 Ma. This should be taken into consideration in studies influenced by the loess cover of an area.

The paleopedology of the world’s largest retrogressive thaw slump, Batagay, is understudied. Micromorphological and geochemical analysis reveal the properties of th host sediments and major pedogenic features. Epigenetic soil profiles of Marine Oxygen Isotope Stage (MIS) 7 (or older) and 5e are clearly distinguished and well developed due to favorable bioclimatic conditions for pedogenesis, probably similar to modern ones. The oldest unit contains a paleosol similar to a Histic Reductaquic Cryosol, indicating a peat-covered, boggy environment. The MIS 5e unit contains organic-rich Histic Spodic Cryosol with well-developed structure, formed during the interglacial optimum, which was relatively warm and presumably resembled modern bioclimatic conditions. MIS 4–3 deposits contains soil-like bodies enriched in coarse organogenic material resembling incipient Histic Reductaquic Cryosols. Interglacial/interstadial units contain micromorphological evidence of aggregate and pore formation, Fe-oxide and organic matter redistribution and clay accumulation. Stadial deposits show weakly expressed soil structure with uneven aggregates, cryogenic disintegration of plant detritus and rare evidence of accumulation of humic substances. Major elemental ratios indicate intensification of biochemical weathering in paleosols and soil-like bodies. Pedogenically reworked material of stadial sedimentary units with sporadic and incipient soil-like bodies provide a significant source for paleoenvironmental reconstruction of harsh Late Pleistocene environments.

We synthesized pre-last glacial maximum pollen records to reconstruct North American pollen diversity since ca. 130 ka. Using taxonomic diversity (a measure of the number and abundance of taxa) and functional diversity (a measure of the number and abundance of different phenotypes) we identified temporal and spatial diversity trends for six North American bioregions: Arctic, Intermountain West, Mexico, Pacific Northwest, Southeast, and Yucatán. Reconstructed taxonomic temporal and spatial trends vary among bioregions, with regional diversity patterns captured in the functional metric, suggesting shifts in species composition coincide with shifts in ecosystem function. However, significant shifts in taxonomic pollen diversity differed in frequency, magnitude, and timing from their functional counterparts. Variations in both regional taxonomic and functional diversity response to global and regional temperature trends were evident, suggesting temperature alone does not fully explain changes in species composition. Regional richness estimates exhibited higher stability relative to the weighted diversity estimates indicating low levels of species turnover through Late Quaternary warming–cooling phases. Shifts in regional diversity did not predictably respond to stadial and interstadial transitions. Instead, North American patterns of plant diversity over the last ca. 130 ka differ geographically, likely responding to regional rather than global climate change.

The central European loess-paleosol sequence (Marine Oxygen Isotope Stage (MIS) 6–2) at three sites located in northwestern Ukraine, in the transitional area between the oceanic and continental climates, has been studied using micromorphological, grain-size, pollen, and magnetic methods. The sequence is characterized by a well-developed pedocomplex S1 (correlative of MIS 5), comprising four soils, and three interstadial soils within loess L1 (MIS 4–2). The soils of S1 are synsedimentary, indicating a dynamic depositional environment with pulses of aeolian sand sedimentation from late MIS 6 to MIS 5a. From various cryogenic features, the permafrost aggradation for MIS 6, 4, and 2, and deep seasonal freezing for MIS 5d and 5b were reconstructed. Distinct redoximorphic features of the loess units, widespread solifluction, well-developed periglacial phenomena, and very low magnetic susceptibility values for the loess-paleosol sequence of northwestern Ukraine reveal its similarity to those of the central European loess subdomain of the northern European loess belt. The low concentration of ferrimagnetic minerals in the parent material and intensive processes of physical and chemical weathering are reflected in the specific model of magnetic enhancement of the studied sequence, which is transitional between the “Chinese” (pedogenic) and “Alaskan” (reducing-pedogenic) models.

We studied a 2200-year-old sediment core from Lake Zapovednoye, a small, deep, freshwater lake near the site of the 1908 Tunguska impact event. Analysis of the sediment core for geochemistry, pollen, chironomids, Cladocera, and diatoms revealed traces of climatic fluctuations during the investigated time period during which a cool climate before 1000 CE was replaced by the Medieval Climatic Optimum, the Little Ice Age, and finally the modern warming. An increased content of terrigenous elements was identified at the depth corresponding to ca. 1908 CE. This layer presumably resulted from erosion of the soil cover after the tree fall caused by the Tunguska impact event (the largest recorded in history). For the first time, the reaction of lake biota to an impact event has been detected. Our study has demonstrated that the taxonomic diversity of hydrobionts (chironomids and cladocerans) significantly declined after the catastrophe, probably due to increased turbidity, and recovered in 6–10 years. The pollen and diatom assemblages, however, demonstrated weaker compositional shifts.