The Sahara was wetter and greener during multiple interglacial periods of the Quaternary, when some have suggested it featured very large (mega) lakes, ranging in surface area from 30,000 to 350,000 km2. In this paper, we review the physical and biological evidence for these large lakes, especially during the African Humid Period (AHP) 11–5 ka. Megalake systems from around the world provide a checklist of diagnostic features, such as multiple well-defined shoreline benches, wave-rounded beach gravels where coarse material is present, landscape smoothing by lacustrine sediment, large-scale deltaic deposits, and in places, tufas encrusting shorelines. Our survey reveals no clear evidence of these features in the Sahara, except in the Chad basin. Hydrologic modeling of the proposed megalakes requires mean annual rainfall ≥1.2 m/yr and a northward displacement of tropical rainfall belts by ≥1000 km. Such a profound displacement is not supported by other paleo-climate proxies and comprehensive climate models, challenging the existence of megalakes in the Sahara. Rather than megalakes, isolated wetlands and small lakes are more consistent with the Sahelo-Sudanian paleoenvironment that prevailed in the Sahara during the AHP. A pale-green and discontinuously wet Sahara is the likelier context for human migrations out of Africa during the late Quaternary.

Lichenometry accurately dates exposure times of glacial moraines and landslides when measuring the longest axis of the largest crustose lichen on many blocks, as demonstrated by numerous examples. In Sweden, the sizes of Rhizocarpon subgenus Rhizocarpon describe five pulses of glacial moraine creation in 120 yr. Six historic California earthquakes, between AD 1800 and 1906, caused many landslides that constrain lichen growth as linear with a dating accuracy of±0.5 yr. Crustose lichen sizes date earthquake-created additions to Sierra Nevada talus with an accuracy of±5 yr. The oldest lichen ages are 400 yr for Lecanora sierrae, 800 yr for Lecidea atrobrunnea, and 1100 yr for Acarospora chlorophana and Rhizocarpon subgenus Rhizocarpon. Lichen sizes also record differing spatial attenuation of ground shaking from the magnitude (Mw) ~7.9 San Andreas earthquake of AD 1857 and the more distant, smaller San Jacinto AD 1800 earthquake, which both caused Sierra Nevada rockfalls. AD 1800 seismic shaking was relatively stronger than that of AD 1857 farther north, perhaps expressing stronger Love and Rayleigh styles of surface waves from the north-trending AD 1800 surface rupture that were particularly efficient in causing rockfalls at greater distances.

Reconstruction of lake-level fluctuations from landform and outcrop evidence typically involves characterizing periods with relative high stands. We developed a new approach to provide water-level estimates in the absence of shoreline evidence for Owens Lake in eastern California by integrating landform, outcrop, and existing lake-core data with wind-wave and sediment entrainment modeling of lake-core sedimentology. We also refined the late Holocene lake-level history of Owens Lake by dating four previously undated shoreline features above the water level (1096.4 m) in AD 1872. The new ages coincide with wetter and cooler climate during the Neopluvial (~3.6 ka), Medieval Pluvial (~0.8 ka), and Little Ice Age (~0.35 ka). Dates from stumps below 1096 m also indicate two periods of low stands at ~0.89 and 0.67 ka during the Medieval Climatic Anomaly. The timing of modeled water levels associated with 22 mud and sand units in lake cores agree well with shoreline records of Owens Lake and nearby Mono Lake, as well as with proxy evidence for relatively wet and dry periods from tree-ring and glacial records within the watershed. Our integrated analysis provides a continuous 4000-yr lake-level record showing the timing, duration, and magnitude of hydroclimate variability along the south-central Sierra Nevada.

The woolly mammoth (Mammuthus primigenius) was widespread in almost all of Europe during the late Pleistocene. However, its distribution changed because of population fluctuations and range expansions and reductions. During Marine Oxygen Isotope Stage 2 (MIS 2), these processes were highly dynamic. Our analyses of 318 radiocarbon dates from 162 localities, obtained directly from mammoth material, confirmed important changes in mammoth range between ~28.6 and ~14.1 ka. The Greenland stadial 3 interval (27.5–23.3 ka) was the time of maximum expansion of the mammoth in Europe during MIS 2. The continuous range was soon fragmented and reduced, resulting in the disappearance of Mammuthus during the last glacial maximum from ~21.4 to ~19.2 ka in all parts of the North European Plain. It is not clear whether mammoths survived in the East European Plain. The mammoth returned to Europe soon after ~19.0 ka, and for the next 3–4 millennia played an important role in the lifeways of Epigravettian societies in eastern Europe. Mammoths became extinct in most of Europe by ~14.0 ka, except for core areas such as the far northeast of Europe, where they survived until the beginning of the Holocene. No significant correlation was found between the distribution of the mammoth in Europe and human activity.

Little is known about terrestrial climate dynamics in the Levant during the penultimate interglacial-glacial period. To decipher the palaeoclimatic history of the Marine Oxygen Isotope Stage (MIS) 6 glacial period, a well-dated stalagmite (~194 to ~154 ka) from Kanaan Cave on the Mediterranean coast in Lebanon was analyzed for its petrography, growth history, and stable isotope geochemistry. A resolved climate record has been recovered from this precisely U–Th dated speleothem, spanning the late MIS 7 and early MIS 6 at low resolution and the mid–MIS 6 at higher resolution. The stalagmite grew discontinuously from ~194 to ~163 ka. More consistent growth and higher growth rates between ~163 and ~154 ka are most probably linked to increased water recharge and thus more humid conditions. More distinct layering in the upper part of the speleothem suggests strong seasonality from ~163 ka to ~154 ka. Short-term oxygen and carbon isotope excursions were found between ~155 and ~163 ka. The inferred Kanaan Cave humid intervals during the mid–MIS 6 follow variations of pollen records in the Mediterranean basins and correlate well with the synthetic Greenland record and East Asian summer monsoon interstadial periods, indicating short warm/wet periods similar to the Dansgaard-Oeschger events during MIS 4–3 in the eastern Mediterranean region.

Schmidt hammer (SH) sampling of 54 10Be-dated granite surfaces from the Pyrenees reveals a clear relationship between exposure and weathering through time (n=52, R2=0.96, P<0.01) and permits the use of the SH as a numerical dating tool. To test this 10Be-SH calibration curve, 100 surfaces were sampled from five ice-front positions in the Têt catchment, eastern Pyrenees, with results verified against independent 10Be and 14C ages. Gaussian modelling differentiates Holocene (9.4±0.6 ka), Younger Dryas (12.6±0.9 ka), Oldest Dryas (16.1±0.5 ka), last glacial maximum (LGM; 24.8±0.9 ka) and Würmian maximum ice extent stages (MIE; 40.9±1.1 ka). These data confirm comparable glacier lengths during the LGM and MIE (~300 m difference), in contrast to evidence from the western Pyrenees (≥15 km), reflecting the relative influence of Atlantic and Mediterranean climates. Moreover, Pyrenean glaciers advanced significantly during the LGM, with a local maximum at ~25 ka, driven by growth of the Laurentide Ice Sheet, southward advection of the polar front, and a solar radiation minimum in the Northern Hemisphere. This calibration curve is available online (http://shed.earth) to enable wider application of this method throughout the Pyrenees.

This paper analyses a series of high-quality continuous records from southeastern Africa to study the spatiotemporal patterning of Holocene hydroclimatic anomalies in the region. Results indicate dominant frequencies of variability at millennial time scales, and a series of anomalies broadly common to all records. Of particular interest, data from the southern Cape coast exhibit periods of wetter/drier conditions that are out of phase with the sites less than 150 km away in the adjacent interior, but in phase with sites in tropical regions over 1000 km to the northeast. To explain such spatial patterns and gradients, we propose that the Agulhas Current may be a critical vector by which tropical climatic signals are propagated along the littoral zone, exerting a dominant, highly localized influence on near-coastal environmental conditions. Limitations in the data available do not allow for a detailed examination of the climatic dynamics related to these phenomena, but this paper highlights a series of avenues for future research to clarify the spatial extent and stability of the patterns observed.

Higher δ15N values in bone collagen of mammoth (Mammuthus primigenius) compared with coeval large herbivores is a classic trait of the mammoth steppe. An exception applies to the Epigravettian site of Mezhyrich (ca. 18–17.4 ka cal BP) in the central East European plains, where mammoth bones have δ15N values equivalent to or in a lower range than those of horse specimens (Equus sp.). We expanded our preliminary dataset to a larger sampling size of mammoth, other large herbivores, and carnivores from contemporaneous and nearby sites of Buzhanka 2, Eliseevichi, and Yudinovo. The unusual low mammoth δ15N values were confirmed at Buzhanka 2 and for some specimens from Eliseevichi, while most individuals from Yudinovo displayed the expected high δ15N values, meaning similar to those of the large canids. The possibility of a contrast in migration pattern is not supported since the δ34S values, a marker of mobility, do not correlate with the δ15N values of mammoth bone collagen. No clear chronological tendency could be revealed, at least not at the scale of radiocarbon dating. The low range in δ15N values is likely to reflect a change in the specific niche of the mammoth in the southern part of its distribution.

Bone accumulation in Palaeolithic archaeological sites is often the result of activities carried out by hunter-gatherer groups. Cultural choices may have influenced prey representation in archaeological assemblages, distorting their palaeoecological meaning. We present a comparison between large mammal and small mammal assemblages from the Upper Palaeolithic sequence of Grotta Paglicci (Apulia, southern Italy) that extends from the Marginally Backed Bladelet Aurignacian (about 39,000 cal yr BP) to the Final Epigravettian (about 13,000 cal yr BP). At Paglicci, the high frequency of horse and ibex remains indicates open and dry environments for most of the Upper Palaeolithic. This is confirmed by the predominance of the common vole among small mammals. The alternation between horse and ibex, which takes place during the Upper Palaeolithic, however, looks to be more related to variations in hunting territories. Taxon frequencies change abruptly at 17,955–16,696 cal yr BP, with an increase in woodland-related ungulates together with micromammals, indicating a climatic evolution towards milder and more humid conditions. Results demonstrate that when the association of ungulate taxa is considered as a whole, it has a good palaeoecological signal, whilst considering taxa separately can help to better understand cultural choices of past hunter-gatherer communities.

Here we report a new find of abundant woody debris and cones in stratum of two sections located to the east of the Qinghai Lake basin in China. Analysis of the anatomical structure of the wood and cones confirmed that they are Picea crassifolia Kom. The results of accelerator mass spectrometry 14C dating indicate that the buried Qinghai spruce grew during 9.7–4.2 ka, and the ages of the large trunks or branches are mainly concentrated within the interval 7.5–6.5 ka. This finding gives direct evidence at the species level about the presence of coniferous forest in the early–middle Holocene in Qinghai lake basin. In addition, the buried cones suggest that the early-middle Holocene environment was suitable for the propagation of Picea crassifolia Kom. The variations in the occurrence of Qinghai spruce forest in the Holocene probably reflect changes in humidity/moisture. The humid early-middle Holocene was suitable for the growth and reproduction of Qinghai spruce forest, while a shift toward an increasingly arid climate during the late Holocene resulted in the disappearance of Picea crassifolia Kom. from the Qinghai Lake basin, although human activities may also have contributed to the environmental change.

The assessment and calibration of representational bias in modern soil phytolith assemblages provide the basis for improving interpretation of fossil phytolith assemblages. We studied soil phytolith representation by comparing phytoliths from living plant communities with those from paired surface soils, representing 39 plant communities in Northeast China. Together with the use of representation indices, the 34 and 30 soil morphotypes observed in forest and grassland samples, respectively, were both classified into the following four groups: “Associated types” were similarly represented in soils and in the corresponding species inventory data; “Over-represented types” and “Under-represented types” were respectively over- and under-represented in soils compared to the inventory data; and, in the case of “Special types,” the relationship with the parent plants was unclear. In addition, the diagnostic types exhibited different degrees of representation, while the most common morphotypes were equally represented between grassland samples and forest samples. On this basis, a comparison between the original and corrected soil phytolith indices of the additional 29 soil samples was conducted. The soil phytoliths frequencies corrected by R-values differed between plots with differing plant compositions, and were moderately consistent with actual plant richness in the plot inventory data. We therefore confirmed that R-values are a promising means of correcting soil phytoliths for representational bias in temperate regions. The corrected soil phytoliths can be used to reliably reflect vegetation variability. Overall, our study provides an improved understanding of soil phytolith representation and offers a potential method for improving the accuracy of paleovegetation reconstruction.

Mapping at a scale of 1:5000 identified 395 rock glaciers in the Uinta Mountains, Utah. The majority of these have areas<20 ha, although the largest covers 97 ha. Rock glaciers have a mean elevation of 3285 m above sea level (range of 2820 to 3744 m above sea level) and exhibit a preference for northerly aspects. Sixty (15%) have a tongue-shaped morphology, whereas 335 (85%) are lobate features protruding from talus along valley walls. Tongue-shaped rock glaciers are found at significantly higher elevations and receive considerably less direct solar radiation each year than lobate rock glaciers. Winter ground temperatures atop representative rock glaciers drop to between −3°C and −5°C. This result, combined with ~0°C water discharging in the summer and water ages >1 year, suggests that at least some of these landforms contain buried ice. Late summer water discharge from two rock glaciers exhibits higher pH and significantly elevated concentrations of some ions compared with lake water, consistent with ablation of internal ice after melting of winter snowpack is complete. Although the amount of water discharging from individual rock glaciers may be small, the aggregate discharge from all rock glaciers and talus could constitute a significant component of streamflow in late summer and fall.

This article interprets the life conditions of woolly mammoths (Mammuthus primigenius) from the Upper Paleolithic archaeological site Kraków Spadzista in Poland. We propose that the mammoths’ irregular mortality profile (also known as age profile) was shaped over several decades by major death events, which serially depleted the youngest cohorts. Taphonomic data and comparisons with other Eurasian archaeological and nonarchaeological sites provide context for hypothesizing that the mammoth-bone assemblage was accumulated at least partly through opportunistic human hunting of the most vulnerable animals in mixed herds. Humans exploited heightened mammoth vulnerability during climatic stress periods, killing and butchering most of the animals, although some mammoths in the assemblage may have died from natural causes. The evidence for environmental stress affecting the mammoths includes paleoecological data about local climatic conditions, the abundant signs of mammoth-bone abnormalities in the assemblage, the relatively smaller size of adult female mammoths compared with those from the similarly dated archaeological site Milovice I (Czech Republic), and the unusually high proportion of juvenile mammoths in the assemblage.

We used a change point analysis on a late Pleistocene–Holocene lake-sediment record from the Chew Bahir basin in the southern Ethiopian Rift to determine the amplitude and duration of past climate transitions. The most dramatic changes occurred over 240 yr (from ~15,700 to 15,460 yr) during the onset of the African Humid Period (AHP), and over 990 yr (from ~4875 to 3885 yr) during its protracted termination. The AHP was interrupted by a distinct dry period coinciding with the high-latitude Younger Dryas stadial, which had an abrupt onset (less than ~100 yr) at ~13,260 yr and lasted until ~11,730 yr. Wet-dry-wet transitions prior to the AHP may reflect the high-latitude Dansgaard-Oeschger cycles, as indicated by cross-correlation of the potassium record with the NorthGRIP ice core record between ~45–20 ka. These findings may contribute to the debates regarding the amplitude, and duration and mechanisms of past climate transitions, and their possible influence on the development of early modern human cultures.

The Channeled Scabland–Palouse region of the Pacific Northwest (PNW) of the United States preserves geomorphic and pedosedimentary records that inform understanding of late Pleistocene–Holocene paleoclimate change in a region proximal to the last glacial period Cordilleran Ice Sheet. We present a clumped (Δ47) and conventional (δ18O, δ13C) isotopic study of Palouse loess–paleosol carbonates in combination with carbonate radiocarbon (14C) dating to provide new measures of regional late–last glacial (~31–20 cal ka BP) and Holocene soil conditions. Average clumped isotope temperatures (T(Δ47)) for last glacial Palouse loess–paleosol carbonates (9±4°C) are significantly lower than those for Holocene-aged carbonates (T(Δ47)=18±2°C) in study sections. Calculated soil water δ18OVSMOW values (−16±2‰) for last glacial carbonates are also offset relative to those for Holocene-aged samples (−11±1‰), whereas calculated soil CO2 δ13CVPDB values are similar for the Holocene (−16.9±0.2‰) and late–last glacial (−16.7±1.1‰) periods. Together, these paleoclimate metrics indicate late–last glacial conditions of pedogenic carbonate formation in the C3 grassland soils of the Palouse were measurably colder (9±5°C) than during the Holocene and potentially reflect a more arid last glacial paleoclimate across the Palouse, findings in agreement with previous proxy studies and climate model simulations for the region.

The Gravettian settlements of Europe are considered as an expression of human adaptation to harsh climates. In Southern Europe, however, favorable vegetation-climate conditions supported hunters-gatherer subsistence and the maintenance of their large-scale networks. This was also the case of the North-Adriatic plain and the Apennine mountain ridge in Italy. Traditionally considered lacking evidence, the northern part of the Apennine ridge has recently yielded the Early Gravettian site of Piovesello, located at 870 m a.s.l. Survey and excavation revealed lithic artifacts in primary position embedded in loamy sediments. Radiocarbon dating, anthracological and extended palynological and microcharcoal analyses have been integrated to reconstruct the palaeoecological context of this camp which was probably positioned above the timberline in an arid rocky landscape, bounding the fronts of local glaciers close to their maximum expansion at the time of Greenland Stadial (GS) 5 (32.04 - 28.9 ka cal BP). Human activity left ephemeral traces represented by lithic artefacts, charcoal, and the introduction of radiolarites from sources in proximity to the site and of chert from very far western sources. Evidence from Piovesello contributes to the reconstruction of human and vegetation ecology during Late Pleistocene glaciations and also provides hints for the historical biogeography of petrophytic plants and their orographic relics in the northern Apennine.

Mixed coniferous forests are widespread at middle elevations in the Northern Rocky Mountains, yet relatively little is known about their long-term vegetation and fire history. Pollen and charcoal records from Twin Lakes, in the Mission Range of northwestern Montana provide information on mixed-coniferous forest development and fire activity over the last 15,000 years. These data suggest an open parkland and minimal fire activity before 13,500 cal yr BP, consistent with cold, dry conditions. Increases in Pinus pollen after 13,500 cal yr BP indicate a transition to closed forests, and a slight rise in fire activity as conditions warmed and fuel biomass increased. High levels of Artemisia pollen between 10,000 and 6000 cal yr BP suggest an open forest during the early Holocene when conditions were warmer and drier than present. Low-severity fires likely maintained open forest/shrublands but produced little charcoal during this interval. Present-day mixed-coniferous forests were established in the last 6 ka and included forest taxa characteristic of low- (Pseudotsuga-Larix/Pinus ponderosa) and high-severity fire regimes (Picea/Abies). Increased climate variability and anthropogenic burning may have helped maintain heterogeneous, mixed-coniferous forests during the last several millennia when climate conditions became cooler and wetter.

Moraines preserved around Mount Xuebaoding (5588 m above sea level) on the eastern margin of the Tibetan Plateau, represent past glacial activity in this area. The chronology of these moraines was established using 10Be exposure dating. The dating results revealed multiple glacial events prior to the late glacial (>14.1±2.2 ka), the late glacial (15.6±1.6 to 11.2±3.0 ka), the early-middle Holocene (9.1±0.9 to 6.7±0.7 ka), and the Neoglacial periods (2.5±0.5 to 1.5±0.1 ka). These glacial stages are consistent with the recalculated ages from surrounding areas throughout the Indian and East Asian monsoon-influenced region on the eastern Tibetan Plateau. Comparing with other paleoclimate indexes, we suggest that the late glacial event was mainly driven by low temperature, the early–middle Holocene event by high precipitation, and the late Holocene/Neoglacial event by low temperature.