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This Special Issue of The Holocene contains 16 research papers based on a symposium at the 11th International Meeting of the European Union of Geosciences held in Strasbourg in April 2001. The aim of the symposium was a state-of-the-art assessment of empirical studies of postglacial marine and terrestrial climatic archives and their integration with numerical climate models. This editorial places the individual papers in the broader context of natural climate variability and anthropogenic impacts on the global climate system, regional differences in climate between maritime and continental areas, and the need for an improved theoretical basis for understanding the underlying causes of environmental change. The focus of the Special Issue is the dynamic and relatively well-understood climate of the North Atlantic and the European realm, where, in relation to the steepest offshore temperature gradient on Earth, observational data are abundant and many recent advances have been made in climate reconstruction from proxy archives. The editorial also contains a summary and overview of the papers included in the four main sections of the Special Issue, which emphasize: (1) numerical modelling experiments; (2) models of glacier buildup and equilibrium-line altitude; (3) marine and terrestrial proxy records of climatic change; and (4) multiproxy palaeoenvironmental reconstruction of a Portuguese lagoonal system. [ABSTRACT FROM AUTHOR]

Bleicher (2013) discussed interpretations proposed by Magny (2004) that Holocene lake-level fluctuations in west-central Europe suggest possible solar forcing of climate. He pointed out that the method used by Magny (2004) is a variant of a cumulative probability function (CPF) and cannot prove solar forcing of central European lake-level changes. He concluded that only few episodes of lake-level changes are climatically driven and that non-climatic factors were dominating. While Bleicher’s paper offers a stimulating contribution to the general debate on CPFs, the present comment is based on an approach which, in contrast to CPFs, excludes any consideration of variations in the probabilities over the time intervals given by calibration of 14C dates, as well as any distinction between types of dates (radiocarbon versus tree ring). It produces a revised pattern of the mid-European high lake-level events for the whole Holocene, supporting the hypothesis proposed in Magny (2004). Comparisons with other regional and North Atlantic palaeoclimatic records suggest that, without excluding other forcing factors, the successive high lake-level events recognised in west-central Europe reflect a combination of three main forcing factors acting on millennial and centennial scales, i.e. orbitally driven changes in insolation, impacts of deglacial outbursts and, possibly, variations in solar activity. Finally, it is clear that further investigations are still needed in order to improve the chronological data set for mid-European lake-level fluctuations, with particular attention to better defining the beginning and end of events. [ABSTRACT FROM AUTHOR]

The topic of this paper is the importance of climate for the population and settlement in medieval and early modern times. Were the demographic crises caused by crop failure and famine or by disease? I begin by reviewing European research (particularly English) relating to the issue. The views of Norwegian historians regarding the causes of the agrarian crisis in the late Middle Ages are then examined. Hasund (Hasund S, 1919, 1944, Den store mannedauden. Or Noregs bondesoge. Glytt og granskingar II, Oslo, pp. 82–161. First printed in Beretning om Norges Landbrukshøiskoles virksomhet 1918–1919) claimed it was the plagues, not the climate, that held the population at a low level to the end of the Middle Ages, a view that has been repeated in recent years by such researchers as Lunden (Lunden K, 2002, Norges landbrukshistorie II, 1350–1814. Frå svartedauden til 17. mai. Oslo) and Moseng (Moseng OG, 2006, Den flyktige pesten. Vilkårene for epidemier i Norge i seinmiddelalder og tidlig nytid. Oslo). This paper claims that the role of the climate has been underestimated, in particular that the climatic shock of several bad years in a row directly and indirectly brought appreciable excess mortality in a country situated so far north. ‘Bad’ years demonstrated through dendrochronology are in many cases reflected in documentary evidence concerning poor corn harvests and high mortality. [ABSTRACT FROM PUBLISHER]

Quantitative reconstruction of past vegetation is one of the primary goals in Quaternary palynology and palaeoecology but still remains difficult. This paper proposes a model, REVEALS, that estimates regional vegetation composition using pollen from ‘large lakes’ that have small site-to-site variations of pollen assemblages even if vegetation is highly heterogeneous. Once these data have been used to quantify regional vegetation composition within 104-105 km², background pollen, one of the parameters crucial for vegetation reconstruction, can be estimated for smaller-sized sites, and incorporated into the Landscape Reconstruction Algorithm (LRA), a multistep framework for quantitative reconstruction of vegetation in smaller areas (≤/104 ha). Simulations using the POLLSCAPE modelling show that REVEALS can provide accurate estimates of regional vegetation composition in various landscapes and under different atmospheric conditions. If pollen assemblages from lakes that are much smaller than ‘large lakes’ are used, estimates of regional vegetation at individual sites could be significantly different from the expected values, and their site-to-site variation could be large. However, when pollen data from multiple lakes ≥100-500 ha in size are available, REVEALS can provide accurate estimates of the regional vegetation with relatively small standard errors. Quantitative reconstruction of regional landscape and vegetation change will be critical for testing some of the controversial hypotheses and concepts in global change and conservation research, such as the impacts of agricultural activities on global climate over the last 8000 years and the open-woodland hypothesis in northern Europe in the early Holocene. [ABSTRACT FROM AUTHOR]

Species distribution models are widely used by ecologists to estimate the relationship between environmental predictors and species presence and abundance records. In this paper, we use compiled faunal assemblage records from archaeological sites located across southwest Asia and southeast Europe to estimate and to compare the biogeography of ancient wild and early domestic cattle (Bos primigenius and Bos taurus). We estimate the contribution of multiple environmental parameters on the explanation of variation in abundance of cattle remains from archaeological sites, and find that annual precipitation and maximum annual temperature are significant predictors of abundance. We then formulate, test, and confirm a hypothesis that states the process of cattle domestication involves a change in the types of environmental ranges in which cattle exploitation occurred by applying a species distribution model to presence-only data of wild and domestic cattle. Our results show that there is an expansion of cattle rearing in more temperate environments, which is a defining characteristic of the European early Neolithic. [ABSTRACT FROM AUTHOR]

The melting of the Scandinavian Ice-Sheet in the early Holocene allowed humans to populate the northernmost parts of Europe. Recent excavations of archaeological sites on the riverbank, floodplain and kame terraces of the River Rena, southeast Norway have defined periods of human occupation in riverside environments, which became ice-free during the last deglaciation. In this paper, we extend the scope of previous archaeological work by examining the sedimentology and chronology of five riverside sedimentary sequences along the River Rena. Our aims were to reconstruct the Holocene evolution of part of the river, and determine whether changes in Holocene settlement patterns might be linked to changes in river evolution and/or climate. Results show: (1) widespread draining of the kame terraces of the River Rena occurred shortly before the first consistent human settlement in the area began c. 8 ka BP; (2) human settlement was maintained until the present day, except during a period of previously undocumented abandonment between c. 4 and 3 ka BP, associated with a sustained period of high river discharge. We link the establishment of first undisputable settlement to reduced water levels as glaciers retreated upstream during a 'warmer' phase of the early Holocene, shortly after the 8.2 ka climatic downturn event. The most recent abandonment of the riverbank settlements 4-3 ka BP occurred during the last phase of glacier advance in the River Rena region, which has been linked to the Europe-wide late- Holocene Thermal Decline (Neoglacial) downturn in climate. [ABSTRACT FROM AUTHOR]

Modern proxy-calibration studies are a powerful tool for paleoecological interpretation. This paper analyzes the relationships among modern pollen rain, vegetation and altitude in the central Pyrenees, where several paleo-palynological studies have been developed, but a modern analog survey is still unavailable. The work analyzes the pollen content of moss polsters from different vegetation communities along an altitudinal transect, as well as the flora and vegetation using the Braun-Blanquet system. DCCA showed that altitude satisfactorily explains both vegetation (r2 = 0.988) and pollen (r2 = 0.841) gradients. Besides the complexity of pollen-vegetation relationships, some regularities were found to be useful for paleoecological and paleoenvironmental interpretation. In general, altitudinal vegetation and pollen patterns show similarities, but pollen belts and boundaries are less well defined, likely because of the homogenizing effect of upward wind transport. Palynological differentiation of montane from subalpine/alpine belts is straightforward from the trends of the more significant pollen types, mainly the low-altitude deciduous trees and the high-mountain herbs. Palynological differences between subalpine and alpine belts, which boundary coincides with the treeline, are more subtle and need quantitative criteria and complementary proxies. From an individual point of view, four main groups of pollen were distinguished, in relation to their usefulness as vegetation and altitudinal indicators: (1) very good indicators, (2) good indicators, (3) non indicators, and (4) allochthonous pollen types. The first two groups resulted to be useful as indicator taxa for modern analogs for paleovegetational and paleoaltitudinal reconstruction, while the latter two groups should be interpreted with caution in paleoenvironmental studies. [ABSTRACT FROM AUTHOR]

This paper examines variability in surface climate and the relationship with two circulation indices using recently produced 200-250 year long European daily and monthly climatic series. Assessments are made of the influence of circulation indices (zonal over western Europe and average pressure over central Europe) on regional temperature, precipitation and drought series for northern and central Europe. Changes in the circulation are shown to be very important during the winter in northern Europe, but only over western and central Europe in summer. Circulation indices in winter, however, only explain up to 25% of surface-climate variability and, except for the British Isles, do not explain any decadal and longer timescale variability in summer. Extreme temperatures and growing-season and frost-season durations and degree-day series are calculated for four sites (Central England, Stockholm, Uppsala and St. Petersburg). Degree-day counts are shown to be very strongly correlated (r > 0.9) to average extended summer ('growing' season, May to September) and extended winter ('frost' season, October to April) temperatures. Durations of the growing and frost seasons are only weakly correlated (r ∼ 0.2-0.4) with the appropriate extended seasonal temperatures or degree-day counts. Warmer growing/frost seasons, therefore, need not necessarily be longer/shorter. Counts of extremely warm days in each year are more highly correlated with the growing-season mean temperature than with coldseason temperature. Similarly, counts of extremely cold days in each year are more highly correlated with cold-season temperature than with growing-season temperature. Both the growing-season temperature and the corresponding degree-day counts clearly show warmer temperatures over all series in Fennoscandia before 1860. Over central Europe, and for the Central England temperature series, growing seasons now are of similar warmth to those before 1860. Annually averaged temperatures across the three regions indicate long-term warming which is, however, almost entirely the result of warming during the October to April period. [ABSTRACT FROM AUTHOR]

In this paper an attempt is made to reconstruct air temperature variations in winter (December, January and February) from 2500 documentary data over the period ad 750–1300 for a region comprising the Benelux countries, eastern France, western Germany, Switzerland and northern Italy. Anomalous (warm and cold) winters were classified on the basis of proxy information on frost, freezing of water bodies, duration of snowcover and untimely activity of vegetation using semiquantitative indices. For the most severe winters during the ‘Medieval Warm Period’ (MWP) as well as for the outstanding warm and dry winter ad 1289/90, possible analogue cases from the last 300 years are considered, analysed, synoptically interpreted and compared with each other. It is concluded that severe winters were somewhat less frequent and less extreme during the MWP, ad 900–1300, than in the ninth century and from 1300 to 1900. Mean air temperatures for 30 year. periods were estimated from linear regression models including indices and instrumental measurements. From ad 1090 to 1179 winter temperatures were at the level of the ‘Little Ice Age’ (LIA). From ad 1180 to 1299 they were at that of the twentieth century. The warm and stable winter climate in the thirteenth century supported subtropical plants such as olive trees in the Po valley (northern Italy) and fig trees around Cologne (Germany). The period ad 1300– 1329 which marks the transition to the LIA was 1°C colder. It is concluded that the 1961–90 level of winter temperatures in western central Europe is still within the threshold of natural variability of the last thousand years, albeit at its upper boundary. [ABSTRACT FROM AUTHOR]

The influence of the 'Little Ice Age' (LIA) on the glaciers of Svalbard has been well documented for a long time. This paper presents new data on the LIA maximum glacier extent and retreat by aerial photo interpretation and Geographic Information Systems (GIS) tools. We also make cartography where all results are shown in greater detail. During the LIA maximum, we find that the glacier area of Svalbard was 38,871 km2, and since then, the total glacier area loss in the archipelago has been 5096 km2 (13.1%). The total current glaciated area from the late 2000s is 33,775 km2. Since the LIA, the glaciers in the main islands of the archipelago have retreated by 12.8% in Spitsbergen, 13.4% in Nordaustlandet, and 16.7% in Barentsøya and Edgeøya. The analysis of the LIA maximum glacier extent in the different major drainage basins shows important differences; about 100 years ago, some glacier basins were more than 19% larger in the western and central regions of Spitsbergen, or even more than 23% larger in southern Nordaustlandet, while other small basins found in the northeast of this island were barely 1% larger. The greatest retreats are found in the tidewater glaciers, more variable and responsive to the water temperature changes, water dynamics, and bathymetry. In addition, the advances at some of these glaciers may correspond with surges, which means that the rapid retreats are caused by the post-surging phases as well as climate. The conclusions of this research point out an important ice loss in all of Svalbard since the LIA and the high vulnerability of this Arctic archipelago to global warming. [ABSTRACT FROM AUTHOR]

While it is acknowledged that an incorrect age datum was used to construct the depth–age relationship for the lower part of the core in question, the conclusions of the paper, which related to salinity changes of the last 10 000 years, are unaffected. [ABSTRACT FROM AUTHOR]

Palaeoecological records provide a rich source of information to explore how plant distribution ranges respond to climate changes, but their use is complicated by the fact that, especially when based on pollen data, they are often spatially too inaccurate to reliably determine past range limits. To solve this problem, we focus on hazel (Corylus avellana), a tree species with large and heavy fruits (nuts), which provide firm evidence of the local occurrence of species in the past. We combine the fossil nut records of hazel from Fennoscandia, map its maximum distribution range during the Holocene thermal maximum (HTM) and compare the fossil record with the Holocene hazel range shift as simulated by the LPJ-GUESS dynamic vegetation model. The results show that the current northern range limit of hazel in central and eastern Fennoscandia is constrained by too short growing seasons and too long and cold winters and demonstrate that the species responded to the HTM warming of about 2.5°C (relative to the present) by shifting its range limit up to 63–64°N, reached a rough equilibrium with the HTM climatic conditions and retreated from there to about 60°N during the last 4000 years in response to the late-Holocene cooling. Thus, the projected future warming of about 2.5°C would reverse the long-term southward retraction of species’ northern range limit in Europe and is likely to lead to hazel being a common, regeneratively reproductive species up to 63–64°N. In addition to the accuracy of the projected warming, the likelihood of this scenario will depend on inter-specific competition with other tree taxa and the potential of hazel to migrate and its population to grow in balance with the warming. In general, the range dynamics from the HTM to the present suggest a tight climatic control over hazel’s range limit in Fennoscandia. [ABSTRACT FROM AUTHOR]

Combining nine tree growth proxies from four sites, from the west coast of Norway to the Kola Peninsula of NW Russia, provides a well replicated (> 100 annual measurements per year) mean index of tree growth over the last 1200 years that represents the growth of much of the northern pine timberline forests of northern Fennoscandia. The simple mean of the nine series, z-scored over their common period, correlates strongly with mean June to August temperature averaged over this region (r = 0.81), allowing reconstructions of summer temperature based on regression and variance scaling. The reconstructions correlate significantly with gridded summer temperatures across the whole of Fennoscandia, extending north across Svalbard and south into Denmark. Uncertainty in the reconstructions is estimated by combining the uncertainty in mean tree growth with the uncertainty in the regression models. Over the last seven centuries the uncertainty is < 4.5% higher than in the 20th century, and reaches a maximum of 12% above recent levels during the 10th century. The results suggest that the 20th century was the warmest of the last 1200 years, but that it was not significantly different from the 11th century. The coldest century was the 17th. The impact of volcanic eruptions is clear, and a delayed recovery from pairs or multiple eruptions suggests the presence of some positive feedback mechanism. There is no clear and consistent link between northern Fennoscandian summer temperatures and solar forcing. [ABSTRACT FROM AUTHOR]

The dominant atmospheric circulation pattern that governs European summer climate is a blocking-like pattern over the British Isles that co-occurs with a low over southeastern Europe. The meridionally oriented configuration of this circulation pattern favours the intrusion of warm air over the northeastern Mediterranean during one mode and over northwestern Europe during its opposite mode. We present a summer temperature reconstruction (1768–2008) for the southeastern node of this teleconnection pattern. This reconstruction is based on maximum latewood density (MXD) measurements of 23 Pinus heldreichii trees from a high-elevation stand in the Pirin Mountains in Bulgaria. The temperature signal in trees from high-elevation, summer-dry regions is stronger in MXD measurements compared with tree-ring width data and our reconstruction reflects well interannual- to decadal-scale summer temperature fluctuations in the Balkans as instrumentally recorded over the twentieth century. Fluctuations in our Bulgarian reconstruction correspond to summer temperature variability in the Balkans, Italy, and the southern Carpathians, but opposing temperature variability patterns are manifested over the British Isles and southern Scandinavia. The strong and consistent anti-phase relationship between our reconstruction and a reconstruction of the summer North Atlantic Oscillation (sNAO) suggests that the sNAO pattern is a main driver of the teleconnection between summer temperatures in southeastern versus northwestern Europe. This teleconnection is most pronounced on interannual timescales and has been stable over the last two centuries. [ABSTRACT FROM AUTHOR]

Climate change and human activities in Europe have altered erosion and riverine sediment transport for thousands of years. The Danube River basin, the second largest watershed in Europe, provides a unique study area to examine these impacts on fluvial discharge through available reconstructed climate data during the ‘Little Ice Age’ cold interval, as well as documented timing of deforestation and large dam emplacement. Suspended sediment flux of the Danube watershed and its variability in response to both climatic adjustments and human influences is analyzed at the sub-basin scale using a numerical modeling approach (HydroTrend 3.0). The system is examined over three time periods under conditions corresponding to: (1) modern day, (2) pre-dam and (3) the ‘Little Ice Age’. Modeled results indicate that modern-day suspended sediment flux is approximately 60% and 80% lower than that simulated under pre-dam and ‘Little Ice Age’ conditions, respectively. Disregarding the effects of modern-day dams, sediment flux has decreased 46% since the ‘Little Ice Age’, largely due to declining rates of deforestation since the mid to late twentieth century. High-resolution (decadal) analyses based solely on climate change, i.e. assuming no human impact, suggest that suspended sediment flux should be approximately 5% higher today than during the ‘Little Ice Age’, despite a 10% decrease in water discharge.This supports the view that human influence is the dominant forcing agent in modifying, and even reversing, natural processes on the Earth’s surface. Results also suggest that a 4°C increase in average European annual temperatures, as predicted by the Intergovernmental Panel on Climate Change for the end of this century, could result in increased sediment flux by 16–63% in individual basins. [ABSTRACT FROM AUTHOR]

Neotropical biomass burning reconstructions synthesized from soil and sedimentary charcoal records indicate a period of reduced biomass burning sustained for several centuries after ~500 cal. yr BP. Proxy records of solar irradiance, El Niño events, temperature, and precipitation document regionally variable climate-related trends that do not account for the uniform reduction in burning across the Neotropics. Decreased human ignition resulting from pandemic-induced mortality offers an alternative, geographically comprehensive explanation. In addition, natural (solar-volcanic) factors can explain only ~1.3 ppm out of the rapid 6–10 ppm CO2 decrease between ad 1525 and the early 1600s. Reforestation following land abandonment due to population collapse has the potential to account for the rest of this CO2 decline, and variations in the 13C/12C of atmospheric CO2 and CH4 are consistent with both a major reduction in Neotropical landscape management by fire and massive reforestation. Our findings are demonstrative of the scale at which pre-industrial human activities influenced Earth’s atmospheric greenhouse gas budget. [ABSTRACT FROM PUBLISHER]

Several studies have used grape harvest date (GHD) as a proxy for temperature variations of the last centuries in Europe. However, the use of grape harvest dates to reconstruct climate is not straightforward, with four possible causes of major flaws. In this study we identify and evaluate the accuracy of GHD as a proxy to past temperature anomalies, uncertainties in the model used to relate temperature to GHD, identity of the grape varieties cultivated in the past, type of wine produced in the past and cultural practices used in the past. Our analyses are based on several phenological and crop models, and on the most complete data set on grape vine phenology and harvest quality. We show that the two methodologies currently used - linear regression models and process-based phenological models - can be accurate, but process-based phenological models ascertain robustness to be applied confidently in different vineyards and different periods. However, we show that several factors can induce a bias in temperature reconstructions using process-based models. We demonstrate the importance of historical information on the studied areas such as the varieties cultivated, the style of wine produced, the quality sought, the agricultural practices, in order to build the most robust model. [ABSTRACT FROM AUTHOR]

Pronounced seasonal variability, particularly in the surface ocean heat flux, imparts an important control that drives thermal stratification of the tide-dominated middle- and high-latitude shelf seas. Bottom water temperature and salinity data, resolved on a grid 20' latitude by 30' longitude, were combined with a regional synthesis of the salinity:δ18O relationship in order to generate a spatial and temporal understanding of oxygen isotopes in seawater around the shelf seas of NW Europe. The data are expressed according to equilibrium calcite (δ18OEq.calcite) and, in the shallow mixed water column, exhibit large seasonal changes that are primarily driven by bottom water temperature. Annual bottom water temperature varies from < 3°C to > 17°C in the southern North Sea, generating a seasonal δ18OEq.calcite signal of up to 3.2‰. The amplitude of the seasonal δ18OEq.calcite signal is significantly damped (0.1-0.2%) in deeper, thermally stratified shelf waters. Maps of the monthly distribution δ18OEq.calcite provide the first systematic overview of the spatial and temporal changes on the NW European shelf and highlight the importance of understanding seasonal growth on the incorporation of geochemical signatures into marine organisms. [ABSTRACT FROM AUTHOR]

Marine localities on the west European shelf have been studied to reconstruct the nearshore palaeoceanography of the last two millennia. The sites form a transect from the Iberian margin northeastward via Scotland to western Norway and Iceland. Proxies used for palaeoclimatic reconstructions include stable isotopes, benthic and planktonic foraminfera, diatoms, dinoflagellates, as well as geochemical and sedimentological parameters. Major changes as well as long-term trends in oceanographic conditions are observed in the records, including a general cooling trend through much of the last millennium. There is a clear linkage between the atmospheric processes and the oceanic circulation, and the ocean temperature variability in the records can be correlated with the so-called 'Mediaeval Warm Period' and 'Little Ice Age'. These oscillations are, however, by no means unique within the last two millennia. As an example, sea surface temperatures to the north of Iceland and on the Iberian margin were higher in the Roman Warm Period than at any time during the 'Mediaeval Warm Period'. However, the palaeoceanographic record generally supports a distinct cooling at the transition between the 'Mediaeval Warm Period' and the 'Little Ice Age'. While a number of records indicate a warming of coastal and shelf waters during the last 200 years, the twentieth century does not appear to be unusual when the proxy records spanning the last two millennia are examined. [ABSTRACT FROM AUTHOR]

Fluctuations in Holocene atmospheric radiocarbon concentrations have been shown to be due to variations in solar activity. Analyses of both [sup 10]Be and [sup 14]C nuclides confirm that production-rate changes during the Holocene were largely modulated by solar activity. Analyses of peat samples from two intact European ombrotrophic bogs show that climatic deteriorations during the 'Little Ice Age' are associated with transitions to increasing atmospheric [sup 14]C content due to greater [sup 14]C production. Both ombrotrophic mires, which are positioned c. 800 km apart, register reactions to globally recorded [sup 14]C fluctuations between AD 1449 and 1464 and an almost identical reaction between AD 1601 and 1604. [ABSTRACT FROM AUTHOR]

The northward spread of hazel (Corylus avellana L.) from its glacial period refuges has been studied for over a century. North of the Alps the course of its pollen curve, in both relative and absolute pollen diagrams, differs from those of other early immigrant trees. There is no long 'tail' of low values before the marked 'rise' to high values. The hypothesis presented is that hazel was present as non-flowering trees beforehand, with full pollen production setting in after a stabilization and amelioration of the climate in the early Holocene. This view is based on a comprehensive survey of all the life history stages of hazel in relation to climatic and other factors, together with indications from radiocarbon dates of the 'rise' phenomenon, not of arbitrary pollen percentage values, for sites north of the Alps. The regional and altitudinal differences in [sup 14]C dates, with due regard to the existence of [sup 14]C plateaux, support the hypothesis, as do other independent estimates of the early-Holocene climate in northern Europe. The role of fluctuating seasonal air temperatures and precipitation is noted and the need to consider the ecological requirements of all stages of any plant species' life history is stressed. [ABSTRACT FROM AUTHOR]

Atmospheric deposition of large-scale lead pollution has occurred for at least 3000 years in Europe. Metal production and smelting were the main sources until the twentieth century when emissions from vehicles using alkyl-leaded petrol became dominant. Analyses of lake-sediment and peat deposits in Sweden and other regions in Europe, as well as ice cores from Greenland, suggest synchronous temporal changes in past pollution deposition. Characteristic features in the atmospheric pollution fallout were caused by: the peak in lead production during the Roman period; the marked Mediaeval increase in mining and metal production; the rapidly increasing use of cars and leaded gasoline after the second world war along with increased industrial emissions until around 1970, which was followed by a major improvement due to environmental legislation. For northern Europe at least, these characteristic changes can be used to determine, with reasonable accuracy, at which levels ad 0, ad 1000–1200 and ad 1970 are situated in lake-sediment deposits. To identify these levels, stable lead isotope analyses ( 206 Pb/207 Pb ratios) have proven to be very useful besides concentration determinations. Particularly useful are the isotope analyses in areas, such as Sweden, where the differences in 206 Pb/207 Pb ratios are large between the natural catchment lead and the pollution lead. [ABSTRACT FROM AUTHOR]

A simulation model is described providing general insights into autocompaction effects in stratigraphic sequences formed on coastal mudflats and marshes over uneven basements. Lithological units and buried landscapes are progressively displaced and distorted, the synthetic sequences resembling bedding geometries described from the northwest European Holocene. Autocompaction also promotes local deposition rates that may greatly exceed the rates at which accommodation space is created. Transgressive silts are associated with especially large deposition rates, because of the high compressibility of underlying peats. The experimental relationships between apparent rates of sea-level rise and bed thickness resemble empirical trends for the Holocene. The latter are, however, reinforced by an ‘intrinsic’, lithology-related effect not included in the model. [ABSTRACT FROM AUTHOR]

Tree-ring records, six from eastern North America and four from northwestern Europe, are used to develop the first reconstruction of the winter North Atlantic Oscillation (NAO). The reconstructed series spans the interval AD 1701-1980 and explains 41% of the variance in the NAO over the AD 1874-1980 calibration period. The reconstruction also captures the spectral properties of this index, suggeting that the oscillatory character of the NAO is a long-term feature of the North Atlantic climate system. [ABSTRACT FROM AUTHOR]