We developed a 1108 yr chronology of tree-ring widths, based on 64 Himalayan pencil juniper (Juniperus semiglobosa Regel) trees, for the Pamir-Alay Mountains, central Asia. Dendroclimatological analysis demonstrates that precipitation has significant effects on tree growth in the semiarid mountainous area of northwestern Tajikistan located on the edge of the great midlatitude Karakum and Kyzylkum deserts. The highest level of linear correlation (r=0.67) is observed between tree growth and seasonalised winter (previous December–February) precipitation. Our studies also show that moisture (precipitation/Palmer Drought Severity Index) from the previous June to the current September was the dominant climatic factor accounting for interannual variations in tree-ring width, suggesting that this should be considered in climate reconstruction. Using the transfer function method, we reconstructed the region’s drought history over the period AD 908–2015. The results of this moisture reconstruction showed that the most recent millennium was characterised by series of dry and wet stages. The driest periods occurred before 1000, 1200–1250, and at the end of the eighteenth century and beginning of the nineteenth century. The wettest conditions existed in 1650–1700 and after 1990.

Interactions of fluvial and eolian processes are prominent in dryland environments and can significantly change Earth surface morphology. Here, we report on sediment records of eolian and fluvial interactions since the last glacial period, in the semiarid area of northwest China, at the limit of the Southeast Asian monsoon. Sediment sequences of last glacial and Holocene terraces of the Yellow River are composed of channel gravels, overlain by flood sands, eolian dunes, and flood loams. These sequences, dated by optically stimulated luminescence, record interlinks between fluvial and eolian processes and their response to climate change. Sedimentologic structures and grain-size analysis show flood loams, consisting of windblown sediment, deposited from floodwater suspended sediment. The gravel and sand were deposited during cold periods. During transitions from cold to warm phases, the river incised, and dunes were formed by deflation of channel and floodplain deposits (>70 and 21–16 ka). Dunes also formed at ~0.8 ka, probably after human intervention. After dune formation, flood loam covered dunes without erosion during peak discharges at the beginning of the subsequent warm period. The fluctuations of the Southeast Asian monsoon as a moisture-transporting agent have perhaps been the driving force for interactions between fluvial and eolian processes in this semiarid environment.

We discuss the cultural roles of dog and red fox recovered from Carlisle Island, Islands of Four Mountains, Alaska, within the context of Aleutian ethnographic and zooarchaeological records. Three dog bones were recovered from the Ulyagan archaeological site, Unit 5, in levels that date to AD 1450–1645. Three red fox bones come from the Ulyagan site, Unit 4, in levels that date 460 BC–AD 95. Our analyses show that both red fox and domestic dog date earlier than the contact with Russians and that these canids do not extend west of the Islands of Four Mountains archipelago. Given the rich history of human intervention on the Aleutians ecosystems over the last 250 years, we argue that indigenous red fox inhabited the Islands of the Four Mountains region prior to western contact; however, foxes did not have a pronounced cultural role for prehistoric Aleuts. Domestic dogs accompanied humans in the Aleutians after AD 950, suggesting that these canids might be linked with the Neo-Aleut culture. In the light of Arctic and oceanic cases of human use of dogs considered in the paper, we suggest that dogs might have served as reserve food sources during long trips for people migrating west.

The multi-layered settlement of Turganik in the Tok River valley (steppe region west of the Urals) has been studied using paleopedological and microbiomorphical methods. Early humans lived in the settlement during the Eneolithic epoch (the fifth millennium BC) and in the Early Bronze Age (the fourth millennium BC). The cultural layers attributable to the Atlantic period of the Holocene developed under conditions of a rather dry climate, with the landscapes being dominated by the grass and herb steppe. The settlement area was above the flood water level and was suitable for habitation. The soils in its vicinity were Kastanozems (Endosalic Protosodic). The final stages of the cultural layer formation bear traces of strong (though short-term) floods, with the deposits of the latter partly concealed traces of the preceding long-term arid phase. Maximum aridity was during the final interval of the Atlantic period. The Subboreal and Subatlantic periods were noted for meadow-chernozem soil formation (Luvic Chernozems [Stagnic]) and an increasing proportion of arboreal species in the pollen assemblages. Some phytoliths of aquatic plants were found in the assemblages dominated by those of meadow grasses. The climate was more humid and cool, although short episodes of aridity were possible.

Large changes in landscape, vegetation, and culture in northwestern (NW) Europe during the first millennium AD seem concurrent with climatic shifts. Understanding of this relation requires high-resolution palaeoclimate reconstructions. Therefore, we compiled available climate reconstructions from sites across NW Europe (extent research area: 10°W–20°E, 45°–60°N) through review of literature and the underlying data, to identify supraregional climatic changes in this region. All reconstructions cover the period from AD 1 to 1000 and have a temporal resolution of ≤50 yr. This resulted in 22 climate reconstructions/proxy records based on different palaeoclimate archives: chironomids (1), pollen (6), Sphagnum mosses (1), stalagmites (8), testate amoebae (4), and tree rings (2). Comparing all temperature reconstructions, we conclude that summer temperatures between AD 1 and 250 were relatively high, and the period between AD 250 and 700 was characterised by colder summer conditions. The period from AD 700 to 1000 was again characterised by warmer summers. These temperature shifts occurred in the whole of NW Europe. In contrast, the compilation of precipitation reconstructions does not show a common pattern across NW Europe either as a result of a heterogeneous precipitation pattern or the lack of suitable and consistent precipitation proxies.

The Aleutian subduction zone is capable of generating magnitude ~9 earthquakes that have local impact and broadcast their destructive power across the Pacific through tsunamis. Field surveys of the tsunami from the 1957 Great Aleutian earthquake (reported Mw 8.6) indicate a tsunami amongst the largest of the twentieth century. In the eastern half of the rupture zone, stranded logs record up to 18 m run-up in the Islands of Four Mountains (IFM) and 32±2 m on Unalaska Island. In conjunction with archaeological studies in the region, these observations show the potential impact of tsunamis on the ancient peoples in the IFM. Simulation of the near-field tsunami produced from the published slip distribution of 1957 is almost an order of magnitude smaller than all field observations. Increasing the earthquake magnitude and amount of eastern slip used in forward models of the tsunami demonstrate that run-up observations can be achieved throughout the eastern Aleutians if the earthquake was more than twice as large—at least Mw 8.8 earthquake with 10–20 m of eastern slip. Additionally, up to five possible IFM paleotsunami deposits agree with the regional picture of regular large events, illustrating the circum-Pacific tsunami hazard from the east-central Aleutians.

Late Quaternary terraces and sediments in the Holy Cross Mountain region of Poland, emplaced within an environment that had evolved following multiple Pleistocene glaciations, provide evidence of increasing anthropogenic influence on landscape development since the Middle Ages, as revealed by research in the Kamionka, Kamienna, Czarna Konecka, and Nida valleys. The development of the “anthropogenic small-scale water retention system” (ASWRS), including numerous artificial ponds, channels, and forges and mills along the watercourses, resulted in changes in river patterns, with additional anthropogenic channels, which in turn reduced the maximum flood-stage levels during the Little Ice Age. With the collapse of the industries and the disappearance of the ASWRS, several major flood events took place. Unknown in the earlier Holocene, and caused by hydrotechnical failures, the geomorphic effects of these catastrophic flash floods significantly exceeded those of natural processes.

The subantarctic island of South Georgia provides terrestrial and coastal marine records of climate variability, which are crucial for the understanding of the drivers of Holocene climate changes in the subantarctic region. Here we investigate a sediment core (Co1305) from a coastal inlet on South Georgia using elemental, lipid biomarker, diatom, and stable isotope data to infer changes in environmental conditions and to constrain the timing of late-glacial and Holocene glacier fluctuations. Because of the scarcity of terrestrial macrofossils and the presence of redeposited and relict organic matter in the sediments, age control for the record was obtained by compound-specific radiocarbon dating of mostly marine-derived n-C16 fatty acids. A basal till layer recovered in Little Jason Lagoon was likely deposited during an advance of local glaciers during the Antarctic cold reversal. After glacier retreat, an oligotrophic lake occupied the site, which transitioned to a marine inlet around 8.0±0.9 ka because of relative sea-level rise. From 7.0±0.6 to 4.0±0.4 ka, reduced vegetation coverage in the catchment, as well as high siliciclastic input and deposition of ice-rafted debris, indicates glacier advances in the terrestrial catchment and likely in the adjacent fjord. A second, less extensive period of glacier advances occurred in the late Holocene, after 1.8±0.3 ka.

A paleoenvironmental reconstruction of the landscape of Nea Raedestos Toumba in the Anthemous River valley in central Macedonia, Greece is undertaken using multidisciplinary geoarchaeological methods. The archaeological site is a settlement mound (tell or toumba) that dates to the Neolithic period and the Bronze Age. The tell’s location on the alluvial plain prompted a multidisciplinary investigation to reconstruct the influence of landscape changes on prehistoric settlements in the valley with an emphasis on alluvial sequences. An electrical resistivity tomography survey and three cores were drilled to study the sedimentary environments in and around the archaeological site. Sedimentologic and palynological analysis combined with accelerator mass spectrometry radiocarbon dating show that the oldest habitation layers at the site, from the Middle and Late Neolithic, were located next to a small, periodically drying water body surrounded by ruderal vegetation. Diatom analysis suggests that this water body was supplied by saline/brackish groundwater. The water body was open until the Early Bronze Age, when it was filled and buried by floodplain sediments. This flooding phase at Nea Raedestos likely occurred at the same time as an increase in fluvial aggradation in the neighboring Thessaloniki Plain, which is dated to the beginning of the third millennium BC.

We compiled present-day observations and survey data of the avian and mammal fauna in the Islands of Four Mountains, Alaska, which primarily consist of marine-adapted species, to provide insight into the prehistoric fauna found in the archaeological record. We documented 63 bird species, mainly seabirds (67%). The majority (71%) of the estimated number of breeding birds are ledge nesters, predominately murres, and most (68%) spend the majority of their lives in the offshore environment. We lack good estimates for burrow and crevice nesters, which were impacted by and are still recovering from a period of arctic fox farming in the twentieth century. Marine mammals, predominately Steller sea lion, harbor seal, and sea otter, primarily use accessible land as haul-outs and are found in low numbers compared with the rest of the Aleutians. Red fox, the only land mammal, presently only reside on Chuginadak Island. While the present-day fauna is similar to the fauna recorded in the archaeological record, we found no indication of nesting by ancient murrelets and northern fulmars in the Island of Four Mountains, whereas both species were present in midden sites on Carlisle and Chuginadak Islands, with the possibility of prehistoric breeding colonies on Carlisle Island.

In the hinterland of the desert, valuable archives of paleoenvironmental evolution are scarce. Calcareous root tubes (CRTs) have a strong potential for reconstructing paleoenvironmental conditions. It is still unclear, however, whether chemical elements in the CRTs can provide insights into paleoenvironmental conditions. In this study, the major- and trace-element composition of 32 CRT samples from the Alashan Desert were analyzed by X-ray fluorescence spectrometry. Results showed that the elemental composition and content change were controlled by the parent material and climatic conditions at the time of CRT formation. Ca, Mg, and Sr were significantly affected by climate, whereas the enrichment of P is likely related to the growth of plants. Higher (lower) Mg/Ca and Sr/Ca ratios corresponded to higher (lower) effective moisture and a higher (lower) Mg/Sr ratio indicated a higher (lower) temperature during the middle Holocene (8–5 cal ka BP). The reconstruction results for effective moisture were consistent with those in the Asian monsoon margin of northwestern China, which were caused by higher monsoon precipitation and lower evaporation. Therefore, chemical elements in the CRTs can reflect changes in paleo-effective moisture and paleotemperature at a millennial resolution in this area.

A detailed, quantitative, multitemporal analysis of historical maps, aerial photos, and satellite images was performed to investigate the channel planform changes that occurred along the Scrivia River floodplain from 1878 to 2016. Various channel planform features, including channel length, area, width, braiding, sinuosity, lateral migration, activity, and stability, were computed through an innovative geographic information system–based procedure, starting from manually digitized active-channel polygons. Three active-channel morphological evolution stages are evident from: (1) 1878 to the 1950s; (2) the 1950s to the end of 1990s; and (3) the end of 1990s onward. In the first period, the river was generally able to migrate in its floodplain, shaping the riverscape. Active-channel narrowing and increasing channel stability characterize the second period. The most recent phase shows an inversion of the morphological evolutionary trend. This last phase is characterized by a slight generalized widening related to the reactivation of stabilized surfaces and to bank-erosion processes. Particularly from the 1950s to the 1990s, in-channel sediment mining and channelization with consequent occupation of riverine areas strongly affected the Scrivia River. These factors, together with floods, are thought to be the most likely causes of such consistent and fast morphological changes.

Coastal lake sediments are valuable paleoclimate archives provided that they can be accurately dated. Here, we report radiocarbon ages of bulk sediment organic matter (OM), plants, shells, particulate OM, and dissolved OM from coastal lakes in Florida. Bulk sediment OM yielded ages that are consistently older than contemporaneous plants and shells, indicating significant radiocarbon deficiencies in sedimentary OM in these lakes. The data show that the OM radiocarbon deficiency varies over time and with location, making it impossible to determine a proper correction factor for radiocarbon ages of bulk sediments from these lakes. As a result, we consider ages obtained from bulk sediment OM from these lakes unreliable. The age reversals in bulk sediment OM observed in the sediment cores are likely caused by rapid increases in erosion and sedimentation resulting from large storm events. The data also show that sedimentation rate can vary considerably within a given lake, implying that an age-depth model established for one core cannot be directly applied to other cores despite their close proximity. Analyses of shells from one of the lakes suggest that fresh/brackish-water shells may serve as a good substrate for radiocarbon dating owing to a small reservoir effect on inorganic carbon.

High-resolution diatom stratigraphies from mid-Holocene sediments taken from fringe and central locations in Moss Lake, a small lake in the foothills of the Cascade Range, Washington, have been analyzed to investigate the impacts (and duration) of tephra deposition on the aquatic ecosystem. Up to 50 mm of tephra was deposited from the climactic eruption of Mount Mazama 7958–7795 cal yr BP, with coincident changes in the aquatic ecosystem. The diatom response from both cores indicates a change in habitat type following blanket tephra deposition, with a decline in tychoplanktonic Fragilaria brevistriata and Staurosira venter and epiphytic diatom taxa indicating a reduction in aquatic macrophyte abundance. Additionally, the central core shows an increase in tychoplanktonic Aulacoseira taxa, interpreted as a response to increased silica availability following tephra deposition. Partial redundancy analysis, however, provides only limited evidence of direct effects from the tephra deposition, and only from the central core, but significant effects from underlying environmental changes associated with climatic and lake development processes. The analyses highlight the importance of duplicate analyses (fringe and central cores) and vigorous statistical analyses for the robust evaluation of aquatic ecosystem change.

Paludification is the most common process of peatland formation in boreal regions. In this study, we investigated the autogenic (e.g., topography) and allogenic (fire and climate) factors triggering paludification in different geomorphological contexts (glaciolacustrine silty-clayey and fluvioglacial deposits) within the Québec black spruce (Picea mariana)–moss boreal forest. Paleoecological analyses were conducted along three toposequences varying from a forest on mineral soil to forested and semi-open peatlands. Plant macrofossil and charcoal analyses were performed on basal peat sections (≤50 cm) and thick forest humus (<40 cm) to reconstruct local vegetation dynamics and fire history involved in the paludification process. Results show that primary paludification started in small topographic depressions after land emergence ca. 8000 cal yr BP within rich fens. Lateral peatland expansion and secondary paludification into adjacent forests occurred between ca. 5100 and 2300 cal yr BP and resulted from low-severity fires during a climatic deterioration. Fires that reduced or eliminated entirely the organic layer promoted the establishment of Sphagnum in microdepressions. Paludification resulted in the decline of some coniferous species such as Abies balsamea and Pinus banksiana. The paleoecological approach along toposequences allowed us to understand the spatiotemporal dynamics of paludification and its impacts on the vegetation dynamics over the Holocene.

Ice-wedge activity can be used to reconstruct past environmental conditions. We investigated the moisture source and timing of ice-wedge formation on the Blackstone Plateau. A section of permafrost exposed ice wedges that developed at two distinct depths: the first set formed syngenetically and penetrated alluvial silts from the top of permafrost; the second set, truncated by an erosional or thaw contact, was found solely in icy muddy gravels (>3.1 m depth). The δ18O and D-excess records of the ice wedges suggest that they formed from freezing of snow meltwater whose isotopic composition evolved during meltout. The 14CDOC results suggest that climate was favorable to ice-wedge growth between 32,000–30,000 and 14,000–12,500 cal yr BP, but there was likely a hiatus during the last glacial maximum due to climate being too dry. During the early to mid-Holocene, ice wedges were inactive as a result of warmer and wetter climate. Ice wedge re-initiated around 6360 cal yr BP, with a peak in activity between 3980 and 920 cal yr BP, a period characterized by cool and moist climate. Overall, timing of ice-wedge activity was broadly consistent with the climate and vegetation evolution in the western Arctic.

Diatom assemblages in lake sediments of Lac Noir, southwestern Québec, were studied at a resolution of 10 yr to determine principal drivers of primary producers for the past ~1000 yr. Generalized additive modeling revealed strong links between broadscale climate intervals of the late Holocene, forest composition, and diatom flora. During the Medieval Warm Period (~AD 1200) and onset of the Little Ice Age (~AD 1450), increases in Tabellaria flocculosa str. IIIp at the expense of Discostella stelligera reflected low lake productivity. At AD 1630, an abrupt shift to cooler temperatures and dry conditions triggered a decline in hemlock (Tsuga), replaced by disturbance and cool-adapted taxa. Greater nutrient availability and soil erosion in the catchment led to a corresponding and rapid increase in diatoms with higher optima for nitrogen, such as Asterionella formosa and Fragilaria crotonensis. After AD 1870, an increase in pollen of taxa associated with disturbances signaled the arrival of Euro-Canadians, and associated nutrient inputs to the lake triggered increases in Stephanodiscus minutulus and Achnanthidium minutissimum. Overall results of the study indicate that climate played an important underlying role in lake-ecosystem dynamics; however, disturbances affecting forest composition had more direct influences on the diatom communities of Lac Noir.