Rapid Climate Change Events Research Articles

The contribution of school social work to climate change education and mental health support

ABSTRACT This narrative review outlines how school social workers, as part of multi-professional school teams, can be involved in climate change education and mental health support. Rapid climate change and extreme weather events pose an existential threat to children and adolescents, triggering a range of climate emotions such as worry, anxiety or anger. International research shows that current and future climate scenarios affect young people's mental health. In order to achieve good health and well-being, and to prevent serious mental health problems, it is essential to be aware of their climate emotions and distress. In the climate crisis, schools, as important social spaces for children and adolescents, are therefore challenged to provide appropriate educational responses and health promotion for students of all ages. School social workers can make a professional contribution by providing education and counselling aimed at promoting emotional regulation and coping, empowerment for climate action, building self-efficacy and resilience to climate change, and developing comprehensive climate and health literacy. Finally, new challenges and tasks that arise in this context and that require the professional development of school social work are highlighted.

Transient vegetation degradation reinforced rapid climate change (RCC) events during the Holocene

High-resolution multi-proxies from geological archives have revealed a series of rapid climate change (RCC) events during the Holocene. These events coincided with the so-called “Bond events”, which were previously linked to a weakened thermohaline circulation. However, the proposed atmosphere-ocean teleconnections associated with these events are regionally distinct, which explains why most previous studies have only explained a subset of the RCC events, depending on region and proxy type; moreover, the suggested mechanisms are much debated. Here, we present a major effort of Holocene transient simulations that identify a series of centennial-scale RCC events that are consistent with records from geological archives. All eight Holocene RCC events were captured in North China (NC) and pervasive throughout the Northern Hemisphere (NH) in experiments with active dynamic vegetation modules (DV), whereas they were largely absent in experiments without DV. These results suggest that the collapse of the terrestrial vegetation and the resulting feedback played a crucial role in RCC events. Our findings supplement or even challenge the notion that North Atlantic cooling, closely linked to ice-rafted debris (IRD) events, was the dominant driver of RCC events.

Rapid climate changes and human dynamics during the holocene in the eastern mediterranean (Lower Strymon Valley, northern Greece)

The study was conducted in the southern part of the lower Strymon valley, in northern Greece, and revealed up to 25 m of fluvio-lacustrine sediments deposited over the last seven millennia. This sedimentary record represents a significant opportunity for high-resolution palaeoenvironmental studies of the period from 6 to 3 ka cal BP linked to land use and climate change. The results of geophysical investigations, multi-proxy sedimentological (grain size, magnetic susceptibility, loss-on-ignition), pollen and NPP analyses, based on high-precision radiocarbon dating enabled reconstruction of past landscapes as well as a comprehensive discussion of anthropogenic responses and their impact on the vegetation cover, especially during periods with well-known Holocene Rapid Climate Change events (5.6, 4.2 and 3.2 ka cal BP).During the 7–5.7 ka cal BP corresponding to the Late and Final Neolithic, wet conditions created an extended lake surrounded by the densely wooded Strymon watershed, followed by a shift to a shallower lake environment that lasted until ca. 4.5 ka cal BP. The continuous presence of anthropogenic taxa suggests the persistence of human activities even in the absence of formally recognized sites, suggesting the relocation of settlements. The first signs of human disturbance of the landscape at regional scale occurred toward 5.2 ka cal BP (onset of the Early Bronze Age). The so-called « 4.2 ka BP event », which coincided with the end of the Early Bronze Age and the transition to the Middle Bronze Age, is divided into three distinct periods (4.35–4.1, 4.1–3.95 and 3.95–3.75 ka cal BP). The first corresponds to gradual aridification before a period with severe dry conditions that marks a tipping point toward wetland contraction. From this period on, diversification, and multiplication of anthropogenic species including Olea, Juglans and Castanea reflect a global trend toward cultural landscapes. The later periods are characterized by dramatic climatic change around 3.2–3 ka cal BP, at the end of Late Bronze Age, and increasing impacts of agro-pastoral activities and forest clearing starting at the beginning of Antiquity, around 2.8 ka cal BP (Thracian period). After the 4.2 ka cal BP event and we suggest that climatic adversity may have acted as a stimulus to innovation and relocation rather than retarding societal development in the region. To conclude, environmental factors in the lower Strymon valley were not sufficient on their own to trigger a social crisis similar to that mentioned in the Middle East.

Rapid environmental changes in the Lake Qinghai basin during the late Holocene

The Lake Qinghai Basin is sensitive to global and regional climate change because of its unique geographical location. It is the hotspot for paleoclimate research in East Asia. In this study, we reconstructed the environmental evolution of the Lake Qinghai since ∼9 ka by using a high-resolution peat and fluvial-lacustrine record (Laoyinggou profile) obtained at the foot of Nanshan Mountain. Based on 8 AMS14C dates and lithology, loss on ignition (LOI), total organic matter (TOC), X-ray fluorescence (XRF) core-scanning measurements, ratio of total organic carbon to nitrogen (TOC/TN), and sediment particle sorting coefficients, we show that during the Middle Holocene (∼9–4.4 ka BP) this region was primarily dominated by the Asian summer monsoon, with a consistent, warm, and humid environment. By contrast, during the late Holocene (4.4 ka to present), the climatic context in this area fluctuated dramatically at the millennial scales. The low TOC content, lower TOC/TN ration and strong hydroclimatic indicate six rapid climate change events, which occurred at ∼4.0 ka, ∼3.6 ka, ∼3.2 ka, ∼2.8 ka, ∼2.1 ka, and ∼1.4 ka, all of which coincided to cold episodes in the North Atlantic Ocean.

Mid- to Late Holocene geomorphodynamics in a long-term settled mountain catchment in the Pergamon micro-region, western Turkey

AbstractFrom 300 BC to AD 300, the city of Pergamon underwent a profound transformation that impacted the rural settlement patterns and the concomitant geomorphodynamics. We present a geoarchaeological study in a long-term settled catchment in the Pergamon micro-region to disentangle the Holocene geomorphodynamics and triggering factors, for example, climate change and human activity. The analyses of eight radiocarbon-dated sediment profiles from the Tekkedere alluvial fan and its catchment indicate four principal sedimentation phases. Phase 1 (ca. 6.2 to 5–4 ka) is dominated by the floodplain aggradation of the receiving Bakırçay River, which is followed by the formation of floodplain soils (phase 2). Substantial geomorphodynamic changes occurred around 4 ka (phase 3), when the edge of the floodplain was buried by fan sediments of the tributary Tekkedere creek. This is attributed to supraregional aridization and rapid climate change events, superimposed by the onset of local human activities. Repeated cycles of coarse- and fine-textured fan sediments with age inversions after ca. 3.8 ka and valley infills younger than 1300 yr BP indicate the strong erosion and redeposition of sediments in phase 4. These increased geomorphodynamics may coincide with the changing settlement pattern and thus reflect human–environment interactions.

Climate change, human health, and resilience in the Holocene

Climate change is an indisputable threat to human health, especially for societies already confronted with rising social inequality, political and economic uncertainty, and a cascade of concurrent environmental challenges. Archaeological data about past climate and environment provide an important source of evidence about the potential challenges humans face and the long-term outcomes of alternative short-term adaptive strategies. Evidence from well-dated archaeological human skeletons and mummified remains speaks directly to patterns of human health over time through changing circumstances. Here, we describe variation in human epidemiological patterns in the context of past rapid climate change (RCC) events and other periods of past environmental change. Case studies confirm that human communities responded to environmental changes in diverse ways depending on historical, sociocultural, and biological contingencies. Certain factors, such as social inequality and disproportionate access to resources in large, complex societies may influence the probability of major sociopolitical disruptions and reorganizations—commonly known as “collapse.” This survey of Holocene human–environmental relations demonstrates how flexibility, variation, and maintenance of Indigenous knowledge can be mitigating factors in the face of environmental challenges. Although contemporary climate change is more rapid and of greater magnitude than the RCC events and other environmental changes we discuss here, these lessons from the past provide clarity about potential priorities for equitable, sustainable development and the constraints of modernity we must address.

Coupled changes in western South Atlantic carbon sequestration and particle reactive element cycling during millennial-scale Holocene climate variability

AbstractContinental shelves have the potential to remove atmospheric carbon dioxide via the biological pump, burying it in seafloor sediments. The efficiency of marine carbon sequestration changes rapidly due to variations in biological productivity, organic carbon oxidation, and burial rate. Here we present a high temporal resolution record of marine carbon sequestration changes from a western South Atlantic shelf site sensitive to Brazil Current-driven upwelling. The comparison of biological records to rare earth element (REE) patterns from authigenic oxides shows a strong relationship between higher biological productivity and stronger particle reactive element cycling (i.e. REE cycling) during rapid climate change events. This is the first evidence that authigenic oxides archive past changes in upper ocean REE cycling by the exported organic carbon. In addition, our data suggest that Brazil Current-driven upwelling varies on millennial-scales and in time with continental precipitation anomalies as registered in Brazilian speleothems during the Holocene. This indicates an ocean–atmosphere control on the biological pump, most probably related to South American monsoon system variability.

RETRACTED ARTICLE:Monsoon climate change based on cloud data and numerical simulation of basketball

Holocene is an important period for the evolution of human civilization and the study of the relationship between climate change and the development of human society. In the Asian monsoon region, monsoon climate change is an important factor affecting social culture and the change of historical dynasties. Therefore, the evolution of Holocene East Asian monsoon and the abrupt change of Millennium scale are the focus of scientific research. Holocene, as a typical interglacial period, is characterized by a series of abrupt climatic events on a millennium scale, such as Holocene rapid climate change (RCC) and high latitude bond events. In this paper, the quality of point cloud data and the quality of point cloud processing and rendering algorithm can be indirectly evaluated by evaluating the image quality of point cloud data directly drawn, so as to study the monsoon climate change. This paper also analyzes the origin of basketball, which originated in Massachusetts. It was invented by James Naismith, a Christian in Springfield, in 1891. It was introduced to China’s Tianjin YMCA in 1895. In 1896, the Tianjin YMCA held a basketball game performance. As a result, modern basketball officially began in China and gradually spread to the whole country extension. Basketball has been invented for more than 100 years. This paper analyzes and simulates the kinematic data of basketball players in the four stages of holding the ball preparation stage, kicking off stage, shooting in the air stage, and landing buffer stage, such as the movement time, joint angle change, and speed change. It promotes the improvement of basketball players’ shooting skills.

Human impact and landscape changes between 3000 and 1000 BC on the Tropea Promontory (Calabria, Italy)

Pollen data were collected from a one-meter peat succession recovered from the top of the Tropea Promontory (Calabria), a territory continuously inhabited throughout Prehistory and Protohistory. The peat was deposited in a small pond/marsh that was gradually filled up. Six14C dates allowed the peat growth to be constrained to between ca. 3000 and 1000 calBC. Considerable landscape and land use changes occurred in the area in that time interval, due to both environmental changes and intensive human activities. An open landscape with scattered oak woods characterized the high plain, whereas on the wet soils surrounding the marsh, wet woodlands ( Alnus), and hygrophilous vegetation (Cyperaceae) developed, their relative abundance being used to mark the local environmental evolution. The occurrence of different anthropogenic indicators reveals that the area was exploited for agricultural practices (cereal cultivation) and livestock grazing, the latter being the main activity practiced around the marsh between the Eneolithic (stable settlements) and the Early-Middle Bronze Age (seasonal presence). The possibility of climatic influence on the peat evolution was studied by comparisons with well-dated isotope records. The marsh contraction phase roughly coincides with the 4.2 ka calBP event, while the end of peat accumulation postdates the 3.0 ka calBP rapid climate change event.

Collapse and continuity: A multi-proxy reconstruction of settlement organization and population trajectories in the Northern Fertile Crescent during the 4.2kya Rapid Climate Change event.

The rise and fall of ancient societies have been attributed to rapid climate change events. One of the most discussed of these is the 4.2kya event, a period of increased aridity and cooling posited as the cause of societal changes across the globe, including the collapse of the Akkadian Empire in Mesopotamia. Studies seeking to correlate social and climatic changes around the 4.2kya event have tended to focus either on highly localized analyses of specific sites or surveys or more synthetic overviews at pan-continental scales, and temporally on the event and its aftermath. Here we take an empirical approach at a large spatial scale to investigate trends in population and settlement organization across the entirety of Northern Fertile Crescent (Northern Mesopotamia and the Northern Levant) from 6,000 to 3,000 cal BP. We use Summed Probability Distributions of radiocarbon dates and data from eighteen archaeological surveys as proxies for population, and a dataset of all settlements over ten hectares in size as a proxy for the degree of urbanization. The goal is to examine the spatial and temporal impact of the 4.2kya event and to contextualize it within longer term patterns of settlement. We find that negative trends are visible during the event horizon in all three proxies. However, these occur against a long-term trend of increased population and urbanization supported through unsustainable overshoot and the exploitation of a drier zone with increased risk of crop failure. We argue that the 4.2kya event occurred during a period of unprecedented urban and rural growth which may have been unsustainable even without an exogenous climate forcing.

Holocene stable isotope record of insolation and rapid climate change in a stalagmite from the Zagros of Iran

We explore Holocene climatic changes recorded by geochemical proxies in a single, well-dated, stalagmite from the northern Zagros Mountains of Iran, a region where stalagmite records have so far only provided short glimpses of Holocene climatic changes. Stalagmite KT-3 from Katalekhor Cave began growing ∼9.5 ka under wet early Holocene conditions coincident with the timing of Sapropel 1. At this time δ18O values were at or below −9.0‰, stalagmite growth diameter was at its maximum, 234U/238U0 activity values were low and trace element contents indicate flushing of the epikarst. Progressive reduction in winter precipitation amount after 7.0 ka, is recorded by increasing δ18O and 234U/238U0 activity values and reduction in trace element contents and growth diameter until ∼2.0 ka. These trends follow the reduction in summer insolation and agree with model-simulated changes in total rainfall and rainwater isotopes. Sub-centennial-scale variability is not a feature of the δ18O or trace element records; this suggests a stable winter recharge regime, a feature that might militate against KT-3 δ18O recording changes in the seasonality of rainfall. KT-3 δ13C compositions are enriched relative to lower altitude stalagmites in the Levant, implying low soil CO2 contribution (thin montane soils). However, a broadly decreasing millennial-scale trend in δ13C suggests that soil carbon contributions increased with time despite the progressive reduction in winter precipitation amount. The δ13C changes probably reflect decreasing summer temperatures and less extreme wintertime coldness, driven by reducing summer- and increasing winter-insolation respectively. These combined effects decreased effective evaporation and improved soil-moisture availability favouring vegetation development during the growth season. The δ13C values also show ∼1.5‰ centennial-scale variability with higher δ13C values between 9.0 and 8.7 ka, 8.3–7.7 ka, 6.5–5.5 ka, 5.4–4.5 ka and ∼4.3–2.0 ka: three of these correspond with Rapid Climate Change (RCC) events based on non-seasalt potassium (K+) in Greenland ice cores. Higher δ13C values indicate poor soil development caused by aridity. The centennial-scale δ13C anomaly (8.3–7.7 ka) is in part overprinted by the ∼160 year-long, 8.2 ka cold/dry event, but culmination ∼7.7 ka corresponds with other records suggesting an intensified Siberian High Pressure system affecting regional climate. The centennial-scale δ13C anomaly between 4.3 and 2.0 ka overlaps the 2.65 to 2.50 ka ‘Assyrian megadrought’ evident in stalagmite stable isotope records in northern Iraq. The KT-3 record is key in better understanding Holocene climate change in the central Zagros region, representative of montane ‘fertile crescent’ environments.

Early to mid-Holocene hydroclimate trends in the western Carpathians of Romania

In this study, we analyse a sequence from Ic Ponor ombrotrophic peat bog in the Apuseni Mountains of NW Romania using a multi-proxy approach (testate amoebae, pollen, microcharcoal, loss on ignition, magnetic susceptibility, radiocarbon dating, lithology) to reconstruct the palaeoenvironmental conditions and the hydroclimate trends that occurred between 12,700 and 6220 cal yr BP. The sequence evolved from a lacustrine phase (between 12,700 cal yr BP and 12,000 cal yr BP) into an ombrotrophic peat bog (12,000–7600 cal yr BP), accumulated in drier climate conditions, with a subdued water table. Subsequently, wetter conditions occurred, with an elevated water table until 6220 cal yr BP, when the peat bog was flooded and peat accumulation paused, a depositional hiatus being marked by a clayey layer. Peat started to accumulate again ca. 100 years ago, under drier conditions. The peat bog records the local and regional responses to rapid climate change events that occurred at 11,400–11,250, 10,500–10,200, 9400–9200, and 8300–8250 cal yr BP. Our quantitative reconstruction of hydrological changes, as well as pre-existing ones for this region, show similar conditions to those that occurred in Central-Eastern Europe between 12,700 and 7600 cal yr BP, but differ from those that occurred between 7600 and 6220 cal yr BP, suggesting a distinct regional character of Middle Holocene climate conditions in Romania.

Survival in a Climate of Change: The Origins and Evolution of Nomadic Dairying in Mongolia

Dairying and cheesemaking originated in the Fertile Crescent during the early Neolithic and then spread widely throughout Southwest Asia and Europe. Rennet coagulated cheesemaking became a key preservation strategy for milk in these regions. A different form of dairying, based on nomadic and semi-nomadic herding, and a different form of milk preservation based on the production of dried acid coagulated and acid-heat coagulated cheeses, developed on the Eurasian steppe and is still practiced in Mongolia today. This work seeks to reconstruct the migration and evolution of dairying and cheesemaking practices from their Neolithic origin in Southwest Asia to Mongolia, and to establish the role that rapid climate change events played in this process.

The African Humid Period, rapid climate change events, the timing of human colonization, and megafaunal extinctions in Madagascar during the Holocene: Evidence from a 2m Anjohibe Cave stalagmite

Stalagmite data from Anjohibe Cave in northwest Madagascar suggest six distinct climate periods from 9.1 to 0.94 ka. Periods I and II (9.1–4.9 ka) were wetter and punctuated by a series of prominent droughts. Periods IV-VI (4–0.94 ka) were much drier and less variable. Period III (4.9-4 ka) marks the transition between wetter and drier conditions and consists of two significant droughts: the first (4.8–4.6 ka) coincides approximately with the end of the African Humid Period and the second (4.3–4.0 ka) may be the expression of the Northern Hemisphere 4.2 ka dry event in northwest Madagascar. Strong positive correlations between δ13C and δ18O values in Periods I-IV (r = 0.63–0.91) suggest that both isotopes were influenced by natural climate changes indicating that humans may not have been present in the area. In contrast, during Periods V (r = 0.07) and VI (r = −0.12) the “decoupling” of δ13C and δ18O might signal an impact from human activities starting around 2.5 ka. Rapid changes in climate during the early and middle Holocene, with prominent droughts lasting up to 800 years, did not kill off Madagascar's megafauna, and neither did a human population, present since the early Holocene if evidence from south Madagascar is reliable. However, many extinctions occurred under the more stable climatic conditions of the late Holocene, despite an antiphase climate relationship between northern and southcentral Madagascar. This suggests that initial human colonization, or significant increase in human population, triggered the megafaunal extinctions by hunting and destruction of megafaunal habitats.

A model for archaeologically relevant Holocene climate impacts in the Aegean-Levantine region (easternmost Mediterranean)

A repeating pattern of multi-centennial-scale Holocene climate events has been widely (globally) documented, and they were termed Rapid Climate Change (RCC) events. Non-seasalt potassium ion (K+) series in Greenland ice cores provide well-constrained timings for the events, and a direct timing relationship has been inferred between these events and the frequency of northerly cold polar/continental air outbreaks over the eastern Mediterranean Sea through gaps in the mountain ranges along the northern margin of the basin. There also appears to be a remarkable timing agreement with major archaeological turnover events in the Aegean/Levantine region. Yet no physically consistent assessment exists for understanding the regional climatic impacts of the events around this critical region. We present a simple 2-dimensional Lagrangian model, which yields a broad suite of physically coherent simulations of the impacts of frequency changes in winter-time northerly air outbreaks over the Aegean/Levantine region. We validate this with existing reconstructions from palaeoclimate proxy data, with emphasis on well-validated sea-surface temperature reconstructions and a highly resolved cave speleothem stable oxygen isotope record from Lebanon. Given that the RCCs were clearly marked by negative sea surface temperature anomalies in the region, we find that the predominant climatic impacts of this winter-time mechanism were “cold and wet,” in contrast with intercalated “warmer and more arid” conditions of non-RCC periods. More specifically, the RCCs are found to be periods of highly variable conditions, with an overall tendency toward cold and wet conditions with potential for flash flooding and for episodic snow-cover at low altitudes, at least in the lower-altitude (lower 1–1.5 km) regions of Crete and the Levant. The modelled winter-anomaly process cannot address underlying longer-term, astronomically forced trends, or the relatively warm and arid anomalies in between RCCs. The latter require further study, for example with respect to potential (summer-time?) extension of evaporative subtropical conditions over the region. Finally, our results imply that the “amount effect” observed in Levantine cave δ18O (and precipitation or drip-water δ18O) may not reflect the conventional concept related to temperature-dependent fractionation and Rayleigh distillation. Instead, it appears to arise from a complex and somewhat counter-intuitive mixing, in shifting proportionalities, between advected (external) and evaporated (Mediterranean) moisture.

Holocene demographic fluctuations, climate and erosion in the Mediterranean: A meta data-analysis

As part of the Changing the Face of the Mediterranean Project, we consider how human pressure and concomitant erosion has affected a range of Mediterranean landscapes between the Neolithic and, in some cases, the post-medieval period. Part of this assessment comprises an investigation of relationships among palaeodemographic data, evidence for vegetation change and some consideration of rapid climate change events. The erosion data include recent or hitherto unpublished work from the authors. Where possible, we consider summed probabilities of 14C dates as well as the first published synthesis of all known optically stimulated luminescence dated sequences. The results suggest that while there were some periods when erosion took place contemporaneously across a number of regions, possibly induced by climate changes, more often than not, we see a complex and heterogeneous interplay of demographic and environmental changes that result in a mixed pattern of erosional activity across the Mediterranean.

Was the Laurentide Ice Sheet significantly reduced during Marine Isotope Stage 3?

Accurately reconstructing the paleogeography of the Laurentide Ice Sheet (LIS) during Marine Isotope Stage 3 (MIS 3; ca. 57,000 to ca. 29,000 yr B.P.) is critical for understanding glacial growth toward the Last Glacial Maximum (LGM), refining sea-level histories, and studying the Earth system response to rapid climate change events. Here, we present a geochronological data set useful for testing hypotheses of global sea level and refining ice sheet configuration through this interval. Data (n = 735) span the entire MIS 3 interval and consist of 14C determinations (n = 651), cosmogenic exposure ages (n = 52), and optically stimulated luminescence dates (n = 32). On that basis, we hypothesize that the central region of the LIS underwent a dramatic reduction in ice from ca. 52 to 40 ka. Key to this hypothesis are geological records at sites in the Hudson Bay Lowlands (east central Canada) that suggest a marine incursion and development of terrestrial landscapes. We show that these landscapes are consistent with recently published glacial isostatic adjustment predictions that include widespread deglaciation of the eastern (Labrador) sector of the LIS with ice buildup over the western (Keewatin) sector at 42 ka. Ice growth from this minimum toward the LGM is likely to have been rapid. The agreement between this data set and modeling predictions prompts the reassessment of key Late Pleistocene records, including Heinrich events, loess deposition in the continental United States, and sedimentological records from the Gulf of Mexico.

A high-resolution pollen record from East China reveals large climate variability near the Northgrippian-Meghalayan boundary (around 4200 years ago) exerted societal influence

The large and rapid climate change event that occurred around 4200 years ago (hereafter the 4.2-kyr event that marks the onset of the Meghalayan stage) is one of the most significant climatic anomalies in the Holocene. It may have exerted profound societal impact globally; however, its triggering mechanism remains uncertain. Here we present a high-resolution, well-dated pollen record covering this interval from the Tianluoshan archaeological site in East China. Our results show that the hydroclimatic conditions in the study area across this event strikingly resembled the regional expression of modern El Niño-Southern Oscillation (ENSO) and exhibited interdecadal ENSO-like variability from ca. 4.50 to 4.00 cal kyr BP. Also, our pollen data indicate a marked shift toward an overall increased intensity and frequency of ENSO-like climate variability from ca. 4.50 to 4.30 cal kyr BP, which was immediately followed by a decline of rice-based agriculture, providing direct evidence for the causal link between climate deterioration and the collapse of Neolithic civilization in East China some 4200 years ago. This observation is in accord with the enhanced ENSO variability reconstructed from proxy records in the tropical Pacific Ocean. As ENSO is intimately coupled with the Asian summer monsoon and the Intertropical Convergent Zone (ITCZ), we suggest that the enhanced ENSO-like climate variability may have triggered the 4.2-kyr event.

Chronological evolution of some morphological, tectonic and volcanic features in Lake Van, based on correlation of seismic and core data

The Lake Van is the largest Lake in Turkey and the fourth largest soda lake in the World. High resolution (HR) seismic data acquired during 2012 reveals sub-lacustrine terraces, delta clinoforms, channel-networks, active faults and volcanic edifices. The seismic data were correlated with the cores recovered during the 2008 coring and 2010 ICDP PaleoVan drilling campaigns, using synthetic seismograms produced from the MSCL data of the age-modelled cores, thus allowing to date seismic reflector surfaces and to discuss the temporal evolution of the some of the morphological features and structures. Sub-lacustrine channel-network systems are well developed on the shelf areas connect with the river drainage systems on land and extend to water depths of more than 100 m. These drainage systems developed during the major low-stand periods of Lake Van, the last two of which occurred during 15 ka BP and the Younger Dryas with water levels at −200 m and −70 m, respectively. High lake levels similar to today during the early Holocene were followed by lake level oscillations with some low-stands during the Late Holocene. The low stands are characterized by terraces and berms located at 15 m below lake surface (mbls), 25 mbls, 35 mbls and 60 mbls, 70 mbls and 105 mbls. They were most likely related to the rapid climate change (RCC) events such as the 4.2 ka aridity event, Dark Age Cold Period, Medieval Warm Period and Little Ice. The volcanic features are located along the Southern Boundary Fault (SBF). A significant NW-SE trending active fault in the eastern shelf left-laterally offsets a channel by about 500 m and has a small reverse component in the HR seismic profiles. This fault is considered to be the source of Mw = 5.7 Edremit Earthquake of 9 November 2011. NW-SE trending normal faults with a right-lateral strike slip component north of the Northern Basin provides extension in the area. Normal faults are also dominant in the Erciş Strait. Using ages of reflector surfaces we estimate a vertical slip rate of 0.40 mm/yr to ∼0.5 mm/yr on the normal faults in the shelf areas over the last 2–3 ka.

Middle-to-late Holocene palaeoenvironmental reconstruction from the A294 ice-cave record (Central Pyrenees, northern Spain)

Perennial ice deposits in caves represent unique, but underexplored, terrestrial sequences that potentially contain outstanding palaeoclimatic records. Here, we present a pioneer palaeoenvironmental study of an ice deposit preserved in a small sag-type cave (A294) in the Central Pyrenees (northern Iberian Peninsula). The 9.25-m-thick sequence, which is dated from 6100 ± 107 to 1888 ± 64 cal BP, represents the oldest known firn ice record worldwide. The stratigraphy (detrital layers, unconformities, and cross stratification), plant macrofossils, and isotopic signature (similarity between the ice linear distribution, δ2H=7.83δ18O+8.4, and the Global Meteoric Water Line) of the ice point to the diagenesis of snow introduced to the cave by winter snowstorms. Four phases of rapid ice accumulation (6100–5515, 4945–4250, 3810–3155, and 2450–1890 cal BP) are related to wetter and colder winters. Comparison of the isotopic composition (δ18O and deuterium excess) of the ice with other paleoclimate records show that both source effects and the North Atlantic Oscillation (NAO) mechanism exert a dominant influence on the ice cave record. The NAO signal may be a combination of source effects and rainfall amount. Three intervals with low ice accumulation occurred between the phases of rapid accumulation and were related to drier, and possibly warmer, winters. These centennial-scale episodes appear to be in-phase with regional arid events, as established from high altitude lacustrine records and can be correlated to global Rapid Climate Change events. The current warming trend has dramatically decreased the volume of the ice deposit in cave A294.