Archaeological sites as markers of Neopleistocene-Holocene hydrological system transformation in the Kurai and Chuya basins, Southeastern Altai: Results of geomorphological and geoarchaeological studies

Multidisciplinary studies using geomorphological, geoarchaeological, and geochronological approaches indicate contrasting environmental changes in Southeastern Altai, beginning in the Late Pleistocene. 29 new radiocarbon dates from the subaerial complex overlying Late Neopleistocene sediments in the high-altitude Kurai and Chuya basins confirm the degradation of a single ice-dammed reservoir in that area before the Early Holocene. In the first half of the Holocene, those basins were filled with isolated lakes. At the mouth of the Baratal River in the western Kurai basin, a reservoir with a water-level of at least 1480 m a.s.l. emerged ca 10–6.5 ka cal BP; whereas in the Chuya depression, numerous residual lakes existed at least 8 ka cal BP. Landslide- and moraine-dammed lakes between the depressions in the Chuya River valley existed until 7–3 ka cal BP, when they drained away. The state of preservation of in situ archaeological sites, their cultural affiliation, and their locations within the depressions and along the main Chuya valley attest to spatial and temporal changes in the hydrological system. This evolution in the second half of the Holocene did not entail major consequences for humans. All cataclysmic flood events took place (occurred) before 10–8 ka cal BP. © 2016 A.R. Agatova, R.K. Nepop, I.Y. Slyusarenko, V.S. Myglan, V.V. Barinov.Geomorphological studies, including radiocarbon dating, were supported by the Russian Foundation for Basic Research (Projects No. 15-05-06028 and 16-05-01035); archaeological and dendrochronological studies were supported by the Russian Science Foundation (Projects No. 14-50-00036 and 15-14-30011 respectively)

Author Correction: Limited capacity of tree growth to mitigate the global greenhouse effect under predicted warming.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Абсолютный и относительный возраст морен стадий Актру и Историческая ледников Центрального Алтая по данным лихенометрии и дендрохронологии

Dendrochronology, and lichenometry were used to determine the relative and absolute age of the Late Holocene moraines of the glaciers of the Aktru, Maashei and Shavla valleys (North Chuya ridge, Central Altai). An array of 86dendrochronological dates, related to moraine deposits, is analyzed, 30 of which are published for the first time. Also, for the first time, data on the relative (lichenometric) age of the young deposits of the Aktru Valley, and data on the lichenometry of the moraines of the Maashey glacier and one of the glaciers of the Shavly valley were obtained. We used the capabilities of each method and the expediency of their combined use in the study area. It was confirmed that the growth rates of lichens on the moraines of the Aktru stage (XVIII–XIX centuries) are generally consistent with the previously published estimates. The moraines of the Historical stage, which date earlier than 1700–2300 years ago, supports the lichens as large as 120–160 mm, but the scattering of their diameters is too large and the assessment of the lichenometric ages of these moraines seems to be problematic, but not completely excluded. The Akkem stage of glacier advance according to the recent publications dates back to the Late Glacial or Early Holocene time; the lichenometry is obviously not applicably at such ancient surfaces. According to dendrochronological dating, the glaciers of the North Chuisky Ridge in the last millennium advanced at least twice up to their maximum extent in the XVII– early XIX and XII centuries. In the 8th century, the sizes of the glaciers possibly, approached modern ones. Aſter the XVII century, the cedar (Pinus Sibirica) in Central Altai significantly reduced its distribution area due to the climate cooling, retreating from the periglacial territories, where it was distributed earlier. All trees that grew near the glaciers, above 2300 m, died. The comparison of the dates of glacier advances in the past millennia with the tree-ring, ice-core, and palynological reconstructions of summer temperature and precipitation show a good correspondence.Методы дендрохронологии и лихенометрии применены для определения относительного и абсолютного возраста позднеголоценовых морен ледников Центрального Алтая (Северо-Чуйский хребет). Установлено, что скорости роста лишайников– индикаторов на моренах стадии Актру– в целом согласуются с опубликованными ранее оценками. По данным дендрохронологического датирования, ледники этого района в последнем тысячелетии имели два максимума наступания: в XII в. и в XVII– начале XIX вв. (максимум продвижения). В VIII в. площадь ледников приближалась к современной. Размеры лишайников подрода Rizocarpon на моренах стадии Актру варьируют от 20 до 41 мм, на моренах Исторической стадии– от 120 до 160 мм, что в спорных случаях позволяет однозначно идентифицировать морену

Археологические памятники как маркер перестройки неоплейстоцен-голоценовой гидросети Курайской и Чуйской впадин (Юго-Восточный Алтай): результаты геолого-геоморфологических и геоархеологических исследований

Multidisciplinary studies using geomorphological, geoarchaeological, and geochronological approaches indicate contrasting environmental changes in southeastern Altai beginning from the Late Pleistocene. Twenty-eight new radiocarbon dates from the subaerial complex overlying Late Neopleistocene sediments in the high-altitude Kurai and Chuya basins confi rm the degradation of a single ice-dammed reservoir in that area during the Early Holocene. In the first half of the Holocene, those basins were filled with isolated lakes. At the Baratal River mouth in the western Kurai basin, a reservoir with a water level of at least 1480 m a.s.l. emerged ca 10-6.5 ka BP, whereas in the Chuya depression, numerous residual lakes had existed at least 8 ka BP. Landslide- and morainedammed lakes between the depressions in the Chuya valley had existed until 7-3 ka BP, when they drained away. The preservation state of in situ archaeological sites, their cultural affiliation, and their location within the depressions and along the main Chuya valley attest to spatial and temporal changes of the hydrological system. This evolution occurred in the second half of the Holocene and did not entail major consequences for humans. © 2016 Siberian Branch of the Russian Academy of Sciences.Geomorphological studies, including radiocarbon dating, were supported by the Russian Foundation for Basic Research (Projects No. 15-05-06028 and 16-05-01035); archaeological and dendrochronological studies were supported by the Russian Science Foundation (Projects No. 14-50-00036 and 15-14-30011 respectively)

Активность ледника Малый Актру (Центральный Алтай) и изменения границы леса в бассейне Актру за исторический период

Major problems of dating of the glaciers activity from the wood residues found in moraines are discussed by the example of Maly Aktru Glacier. First of all, these are the underestimation of the glacier development features, the age of the sample itself and its content as well as losses of some outer rings. The study proves that disagreements between dendrochronological and radiocarbon ages of the samples are caused by manifestation of the Suess effect and contents of the wood cells. The reconstruction of June–July temperatures in the Aktru valley for two thousand years was used to reconstruct the altitudinal variability of the tree line thermal potential. Existence of a climatic optimum (I–IV A.D.) had been revealed that brought to the higher position of the tree line in mid ages than its thermal potential could enable. On the basis of variability of growth indices for Siberian larch, it is shown that the medieval optimum stands out against a background of solely strong temperature depressions separating it from ancient and modern times, and the climate’s natural history is evidence that the current climate warming is an ordinary phenomenon.Рассматриваются проблемы датирования активности ледников по древесным остаткам, находящимся в морене, на примере ледника Малый Актру. Анализируются причины расхождения между дендрохронологическим и радиоуглеродным возрастом образцов. Реконструируется ход июньской и июльской температуры в долине р. Актру за две тысячи лет, и на базе этого восстанавливается картина высотной изменчивости термического потенциала границы леса. Основываясь на ходе естественной истории климата, показывается рядовой характер современного потепления

Prominent role of volcanism in Common Era climate variability and human history

Climate reconstructions for the Common Era are compromised by the paucity of annually-resolved and absolutely-dated proxy records prior to medieval times. Where reconstructions are based on combinations of different climate archive types (of varying spatiotemporal resolution, dating uncertainty, record length and predictive skill), it is challenging to estimate past amplitude ranges, disentangle the relative roles of natural and anthropogenic forcing, or probe deeper interrelationships between climate variability and human history. Here, we compile and analyse updated versions of all the existing summer temperature sensitive tree-ring width chronologies from the Northern Hemisphere that span the entire Common Era. We apply a novel ensemble approach to reconstruct extra-tropical summer temperatures from 1 to 2010 CE, and calculate uncertainties at continental to hemispheric scales. Peak warming in the 280s, 990s and 1020s, when volcanic forcing was low, was comparable to modern conditions until 2010 CE. The lowest June–August temperature anomaly in 536 not only marks the beginning of the coldest decade, but also defines the onset of the Late Antique Little Ice Age (LALIA). While prolonged warmth during Roman and medieval times roughly coincides with the tendency towards societal prosperity across much of the North Atlantic/European sector and East Asia, major episodes of volcanically-forced summer cooling often presaged widespread famines, plague outbreaks and political upheavals. Our study reveals a larger amplitude of spatially synchronized summer temperature variation during the first millennium of the Common Era than previously recognised

The influence of decision-making in tree ring-based climate reconstructions.

Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets. Taken together as an ensemble, the Common Era reconstruction mean correlates with instrumental temperatures from 1794-2016 CE at 0.79 (p < 0.001), reveals summer cooling in the years following large volcanic eruptions, and exhibits strong warming since the 1980s. Differing in their mean, variance, amplitude, sensitivity, and persistence, the ensemble members demonstrate the influence of subjectivity in the reconstruction process. We therefore recommend the routine use of ensemble reconstruction approaches to provide a more consensual picture of past climate variability

Siberian silkmoth in the Republic of Tyva, the history of studies

Siberian silkmoth (eggar) Dendrolimus sibiricus Tsch., (1908) is one of the most dangerous forest pests in the Republic of Tyva. Outbreaks of this phytophage in the republic occur frequently and cause significant damage to forests. Studies in Tyva were initiated by A. I. Cherepanov, N. G. Kolomiets, N. F. Reimers and others in the 50–70s of the XX century. They described the phenology of the Siberian silkmoth, the biological and ecological aspects of its life activity. In this paper we tried to summarize all the accumulated knowledge of the Siberian silkmoth in Tyva. The chronology of the Siberian silkmoth outbreaks was restored using the collected and analyzed data. We demonstrate that outbreaks of the Siberian silkmoth in the Republic of Tyva are most frequently observed in the forests of Shagonarsky, Chadansky and Turan forestry districts. On the whole, five outbreaks were registered: in 1954–1966, 1969–1975, 1979–1985, 1997–2000, and in 2009–2011. Duration of the outbreaks was 13–7–7–4–3 years and the intervals without outbreaks were 2–1–2–1 years. The fragmented character of the obtained data on outbreaks shows the need for their verification by dendrochronological methods. Valid analysis of data is possible with the use of control tree species not susceptible to the Siberian moth damage and some parameters of the annual rings, for example, optical density of the wood

Revising midlatitude summer temperatures back to A.D. 600 based on a wood density network

Annually resolved and millennium-long reconstructions of large-scale temperature variability are primarily composed of tree ring width (TRW) chronologies. Changes in ring width, however, have recently been shown to bias the ratio between low- and high-frequency signals. To overcome limitations in capturing the full spectrum of past temperature variability, we present a network of 15 maximum latewood density (MXD) chronologies distributed across the Northern Hemisphere extratropics. Independent subsets of continental-scale records consistently reveal high MXD before 1580 and after 1910, with below average values between these periods. Reconstructed extratropical summer temperatures reflect not only these long-term trends but also distinct cooling pulses after large volcanic eruptions. In contrast to TRW-dominated reconstructions, this MXD-based record indicates a delayed onset of the Little Ice Age by almost two centuries. The reduced memory inherent in MXD is likely responsible for the rapid recovery from volcanic-induced cooling in the fourteenth century and the continuation of warmer temperatures until ~1600.Publisher PDFPeer reviewe

A Millennium-Long Tree-Ring Chronologies Koksu and Tara on Altay

В статье представлены две новые тысячелетние древесно-кольцевые хронологии по лиственнице сибирской (Larix sibirica Ldb.) на верхней границе леса: Tara (для периода с 795 по 2011 г., Южно-Чуйский хребет) и Koksu (для периода с 588 по 2011 г., Катунский хребет). Расчет функции отклика показал, что основное воздействие на радиальный прирост древесно-кольцевой хронологии Koksu оказывают температуры июня и июля, а древесно-кольцевой хронологии Tara – только июня. Древесно-кольцевая хронология Koksu характеризуется наличием устойчивой и значимой связи с рядами наблюдений метеостанций, расположенных в Северной Монголии и Китае, т.е. она отражает изменчивость раннелетней температуры как минимум регионального масштаба. Древесно-кольцевая хронология Tara менее чувствительна к изменению летних температур и может быть пригодна для дендроиндикации геоморфологических, исторических и климатических событий (определение времени повреждения деревьев в ходе обвалов, селей, датировка древесины археологических памятников и т.п.). Анализ выявленных аномальных структур и выпавших колец на образцах позволил определить даты экстремальных событий для каждой хронологииThe work presents two new 1000-year tree-ring chronologies: Tara (AD 795-2011, the South Chui Range) and Koksu (AD 588-2011, the Katun Range). The calculation of the response function shows that the dominating factor affecting the radial growth of the tree-ring chronology Koksu is June and July temperatures and for Tara it is June temperature. The strong correlation between Koksu chronology and records of meteorological stations placed in the Northern Mongolia and China at a distance of 300 or more kilometers from the sites of sample collection illustrates that the chronology reflects summer temperature changes at least on a regional scale. At the same time Tara chronology is weakly sensitive to changes in summer temperatures and may be used for dating of geomorphologic, historical and climatic events. The analysis of abnormal structures and missing rings detected on the samples revealed the dates of extreme events for each chronolog