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This paper describes long-term changes in human population and vegetation cover in southern France, using summed radiocarbon probability distributions and site count data as population proxies and information from fossil pollen cores as a proxy for past land cover. Southern France is particularly well-suited to this type of study as a result of previous programmes of intensive survey work and excavation in advance of large-scale construction. These make it possible to calibrate the larger scale occupation patterns in the light of the visibility issues created by the burial of archaeological sites beneath alluvial sediments. For purposes of analysis, the region was divided into three biogeographical zones (BGZ), going from the Mediterranean coast to the middle Rhône valley (MRV). All the different population proxies in a given zone show broadly similar patterns of fluctuation, though with varying levels of resolution. The long-term patterns in the different zones all show significant differences from the overall regional pattern, but this is especially the case for the non-Mediterranean middle Rhône area. Cluster analysis of pollen samples has been carried out to identify the main regional land cover types through the Holocene, which are increasingly dominated by open types over time. A variety of other pollen indicators show evidence of increasing human impact through time. Measures of human impact correlate strongly with the population proxies. A series of thresholds are identified in the population–human impact trajectory that are related to other changes in the cultural sequence. The lack of independent climate data for the region means that its impact cannot currently be assessed with confidence. However, for the later periods, it is clear that the incorporation of southern France into larger regional systems played a major role in accounting for changes in land cover and settlement.

Here we identify and analyze proxy data interpreted to reflect hydro-climatic variability over the last 10,000 years from the Mediterranean region to (1) outline millennial and multi-centennial-scale trends and (2) identify regional patterns of hydro-climatic variability. A total of 47 lake, cave, and marine records were transformed to z-scores to allow direct comparisons between sites, put on a common time scale, and binned into 200-year time slices. Six different regions were identified based on numerical and spatial analyzes of z-scores: S Iberia and Maghreb, N Iberia, Italy, the Balkans, Turkey, and the Levant, and the overall hydro-climate history of each region was reconstructed. N Iberia is largely decoupled from the five other regions throughout the Holocene. Wetter conditions occur in the five other regions between 8500 and 6100 yr BP. After 6000 yr BP, climate oscillated until around 3000 ± 300 yr BP, which seems to have been the overall driest period in the eastern Mediterranean and North Africa. In contrast, Italy and N Iberia seem to have remained wetter during this period. In addition, non-metric multidimensional scaling (nMDS) was applied to 18 long, continuous climate z-score records that span the majority of the Holocene. nMDS axes 1 and 2 illustrate the main trends in the z-score data. The first axis captures a long-term development of drier condition in the Mediterranean from 7900 to 3700 yr BP. Rapid shifts occur in nMDS axis 2 at 6700–6300 BP, 4500–4300 BP, and 3500–3300 BP indicating centennial-scale climate change. Our synthesis highlights a dominant south/east versus north/west Mediterranean hydro-climate dipole throughout the Holocene and therefore confirms that there was no single climate trajectory characterizing the whole Mediterranean basin during the last 10 millennia.

Much attention has been placed on the drivers of vegetation change on the Iberian Peninsula. While climate plays a key role in determining the species pools within different regions and exerts a strong influence on broad vegetation patterning, the role of humans, particularly during prehistory, is less clear. The aim of this paper is to assess the influence of prehistoric population change on shaping vegetation patterns in eastern Iberia and the Balearic Islands between the start of the Neolithic and the late Bronze Age. In all, 3385 radiocarbon dates have been compiled across the study area to provide a palaeodemographic proxy (radiocarbon summed probability distributions (SPDs)). Modelled trends in palaeodemographics are compared with regional-scale vegetation patterns deduced from analysis of 30 fossil pollen sequences. The pollen sequences have been standardised with count data aggregated into contiguous 200-year time windows from 11,000 cal. yr BP to the present. Samples have been classified using cluster analysis to determine the predominant regional land cover types through the Holocene. Regional human impact indices and diversity metrics have been derived for north-east and south-east Spain and the Balearic Islands. The SPDs show characteristic boom-and-bust cycles of population growth and collapse, but there is no clear synchronism between north-east and south-east Spain other than the rise of Neolithic farming. In north-east Iberia, patterns of demographic change are strongly linked to changes in vegetation diversity and human impact indicator groups. In the south-east, increases in population throughout the Chalcolithic and early Bronze Age result in more open landscapes and increased vegetation diversity. The demographic maximum occurred early in the 3rd millennium cal. BP on the Balearic Islands and is associated with the highest levels of human impact indicator groups. The results demonstrate the importance of population change in shaping the abundance and diversity of taxa within broad climatically determined biomes.

Solar ultraviolet-B (UV-B) irradiance that reaches the Earth’s surface acts as a biotic stressor and has the potential to modify ecological and environmental functioning. The challenges of reconstructing ultraviolent (UV) irradiance prior to the satellite era mean that there is uncertainty over long-term surface UV-B patterns, especially in relation to variations in solar activity over centennial and millennial timescales. Here, we reconstruct surface UV-B irradiance over the last 650 years using a novel UV-B proxy based on the chemical signature of pollen grains. We demonstrate a statistically significant positive relationship between the abundance of UV-B absorbing compounds in Pinus pollen and modelled solar UV-B irradiance. These results show that trends in surface UV-B follow the overall solar activity pattern over centennial timescales, and that variations in solar output are the dominant control on surface level UV-B flux, rather than solar modulated changes in ozone thickness. The Pinus biochemical response demonstrated here confirms the potential for solar activity driven surface UV-B variations to impact upon terrestrial biotas and environments over long timescales.

Quantification of vegetation cover from pollen analysis has been a goal of palynologists since the advent of the method in 1916 by the great Lennart von Post. Pollen-based research projects are becoming increasingly ambitious in scale, and the emergence of spatially extensive open-access datasets, advanced methods and computer power has facilitated sub-continental analysis of Holocene pollen data. This paper presents results of one such study, focussing on the Mediterranean basin. Pollen data from 105 fossil sequences have been extracted from the European Pollen database, harmonised by both taxonomy and chronologies, and subjected to a hierarchical agglomerative clustering method to synthesise the dataset into 16 main groupings. A particular focus of analysis was to describe the common transitions from one group to another to understand pathways of Holocene vegetation change in the Mediterranean. Two pollen-based indices of human impact (OJC: Oleaceae, Juglans, Castanea; API: anthropogenic pollen indicators) have been used to infer the degree of human modification of vegetation within each pollen grouping. Pollen-inferred cluster groups that are interpreted as representing more natural vegetation states show a restricted number of pathways of change. A set of cluster groups were identified that closely resemble anthropogenically-disturbed vegetation, and might be considered anthromes (anthopogenic biomes). These clusters show a very wide set of potential pathways, implying that all potential vegetation communities identified through this analysis have been altered in response to land exploitation and transformation by human societies in combination with other factors, such as climatic change. Future work to explain these ecosystem pathways will require developing complementary datasets from the social sciences and humanities (archaeology and historical sources), along with synthesis of the climatic records from the region.

We are surprised at Wainwright and Ayala’s (1) unjustified critique of our recent report in PNAS (2). First, we openly acknowledge that the changes in δ2H18:0 values are not statistically significant; indeed, we report a P value of 0.10 ( t test) and a relatively high SD within each phase (7‰) (2). Thus, the points made by Wainwright and Ayala (1) add little to what we discuss in our paper. Notwithstanding this, our proxy provides a new way of deriving precipitation-related climate records from archaeological sites as a means of exploring links between climatic and cultural changes in human prehistory, a matter they seem to dismiss prematurely in promoting their seemingly antienvironmental-determinism … [↵][1]1To whom correspondence should be addressed. Email: melanie.salque{at}bristol.ac.uk. [1]: #xref-corresp-1-1

Olive (Olea europaea L.) was one of the most important fruit trees in the ancient Mediterranean region and a founder species of horticulture in the Mediterranean Basin. Different views have been expressed regarding the geographical origins and timing of olive cultivation. Since genetic studies and macro-botanical remains point in different directions, we turn to another proxy - the palynological evidence. This study uses pollen records to shed new light on the history of olive cultivation and large-scale olive management. We employ a fossil pollen dataset composed of high-resolution pollen records obtained across the Mediterranean Basin covering most of the Holocene. Human activity is indicated when Olea pollen percentages rise fairly suddenly, are not accompanied by an increase of other Mediterranean sclerophyllous trees, and when the rise occurs in combination with consistent archaeological and archaeobotanical evidence. Based on these criteria, our results show that the southern Levant served as the locus of primary olive cultivation as early as similar to 6500 years BP (yBP), and that a later, early/mid 6th millennium BP cultivation process occurred in the Aegean (Crete) - whether as an independent large-scale management event or as a result of knowledge and/or seedling transfer from the southern Levant. Thus, the early management of olive trees corresponds to the establishment of the Mediterranean village economy and the completion of the 'secondary products revolution', rather than urbanization or state formation. From these two areas of origin, the southern Levant and the Aegean olive cultivation spread across the Mediterranean, with the beginning of olive horticulture in the northern Levant dated to similar to 4800 yBP. In Anatolia, large-scale olive horticulture was palynologically recorded by similar to 3200 yBP, in mainland Italy at similar to 3400 yBP, and in the Iberian Peninsula at mid/late 3rd millennium BP.

International audience; This paper explores long-term trends in human population and vegetation change in the Levant from the early to the late Holocene in order to assess when and how human impact has shaped the region’s landscapes over the millennia. To do so, we employed multiple proxies and compared archaeological, pollen and palaeoclimate data within a multi-scalar approach in order to assess how Holocene landscape dynamics change at different geographical scales. We based our analysis on 14 fossil pollen sequences and applied a hierarchical agglomerative clustering and community classification in order to define groups of vegetation types (e.g. grassland, wetland, woodland, etc.). Human impact on the landscape has been assessed by the analysis of pollen indicator groups. Archaeological settlement data and Summed Probability Distribution (SPD) of radiocarbon dates have been used to reconstruct long-term demographic trends. In this study, for the first time, the evolution of the human population is estimated statistically and compared with environmental proxies for assessing the interplay of biotic and abiotic factors in shaping the Holocene landscapes in the Levant.

Supplemental material, Supplemental_material_1_final for Holocene land cover and population dynamics in Southern France by Jean-François Berger, Stephen Shennan, Jessie Woodbridge, Alessio Palmisano, Florence Mazier, Laure Nuninger, Sebastien Guillon, Elise Doyen, Carole Begeot, Valérie Andrieu-Ponel, Julien Azuara, Andrew Bevan, Ralph Fyfe and C Neil Roberts in The Holocene

Supplemental material, Supplementary_Table_2_(Pollen) for Long-term trends of land use and demography in Greece: A comparative study by C Neil Roberts, Ralph Fyfe, Stephen Shennan, Andrew Bevan, Jessie Woodbridge, Alessio Palmisano, Erika Weiberg, Andrew Bevan, Katerina Kouli, Markos Katsianis, Jessie Woodbridge, Anton Bonnier, Max Engel, Martin Finn�, Ralph Fyfe, Yannis Maniatis, Alessio Palmisano, Sampson Panajiotidis, C Neil Roberts and Stephen Shennan in The Holocene

Supplemental material, SI_3 for Pollen-inferred regional vegetation patterns and demographic change in Southern Anatolia through the Holocene by Jessie Woodbridge, C Neil Roberts, Alessio Palmisano, Andrew Bevan, Stephen Shennan, Ralph Fyfe, Warren J Eastwood, Adam Izdebski, Canan Çakırlar, Henk Woldring, Nils Broothaerts, David Kaniewski, Martin Finné and Inga Labuhn in The Holocene

This paper introduces a special issue on The Changing Face of the Mediterranean: Land Cover, Demography, and Environmental Change, which brings together up-to-date regional or thematic perspectives on major long-term trends in Mediterranean human–environment relations. Particularly, important insights are provided by palynology to reconstruct past vegetation and land cover, and archaeology to establish long-term demographic trends, but with further significant input from palaeoclimatology, palaeofire research and geomorphology. Here, we introduce the rationale behind this pan-Mediterranean research initiative, outline its major sources of evidence and method, and describe how individual submissions work to complement one another.

© The Author(s) 2019. 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 14 C 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. ispartof: HOLOCENE vol:29 issue:5 pages:864-885 ispartof: location:SPAIN status: published

Supplemental material, Supplementary_Table_3_(Site_survey) for Long-term trends of land use and demography in Greece: A comparative study by C Neil Roberts, Ralph Fyfe, Stephen Shennan, Andrew Bevan, Jessie Woodbridge, Alessio Palmisano, Erika Weiberg, Andrew Bevan, Katerina Kouli, Markos Katsianis, Jessie Woodbridge, Anton Bonnier, Max Engel, Martin Finn�, Ralph Fyfe, Yannis Maniatis, Alessio Palmisano, Sampson Panajiotidis, C Neil Roberts and Stephen Shennan in The Holocene

Supplemental material, Supplementary_Table_1_(Radiocarbon) for Long-term trends of land use and demography in Greece: A comparative study by C Neil Roberts, Ralph Fyfe, Stephen Shennan, Andrew Bevan, Jessie Woodbridge, Alessio Palmisano, Erika Weiberg, Andrew Bevan, Katerina Kouli, Markos Katsianis, Jessie Woodbridge, Anton Bonnier, Max Engel, Martin Finn�, Ralph Fyfe, Yannis Maniatis, Alessio Palmisano, Sampson Panajiotidis, C Neil Roberts and Stephen Shennan in The Holocene

This paper compares changes in vegetation structure and composition (using synthetic fossil pollen data) with proxy data for population levels (including settlements and radiocarbon dates) over the course of the last 10 millennia in Tyrrhenian central Italy. These data show generalised patterns of clearance of woodland in response both to early agriculturalists and urbanism, as well as the specific adoption of tree crops and variations in stock grazing. The results provide a comprehensive understanding of the development of the anthropogenised landscape of one of the most important early centres of European civilisation, showing regional trends as well as local variations.

The aim of this work is to reconstruct the periods of growth and decline of human populations in Morocco and their potential impacts on the landscapeover the past 10,000 years. In order to estimate the trends in the human population size between 10,000 and 3000 years ago, we used a summedprobability distribution (SPD) of radiocarbon dates from a wide range of archaeological sites throughout Morocco. Landscape changes were identified andquantified from a dataset of fossil pollen records. Different anthropogenic pollen markers, as well as natural vegetation groups and taxonomic richnesswere used to analyse the relationship between long-term trends in human population expansion or regression and type of impact on the landscape. Thesub-regions of Morocco have different topographies and climates, which have either favoured or prevented the establishment and/or spread of humanpopulations. In order to identify the areas most significantly impacted by humans and the timing of such impacts, we have reconstructed and compared the same past anthropogenic and landscape proxies along with the population trends within the lowlands and mountainous areas. The lowlands were morestrongly impacted earlier in the Holocene than the mountainous areas. Anthropogenic markers indicate that farming expanded in the lowlands duringthe first major expansion of human populations between ca. 7200 and 6700 cal. yr BP at the start of the Neolithic period. In the Atlas and Rif Mountains,anthropogenic impact is not clearly detectable in any of these areas before 4000 cal. BP.

This synthesis paper offers a comparative perspective on how seven different Mediterranean regions, from Iberia and Morocco to the Levant, have been transformed by human and natural agencies during the past 10 millennia. It draws on a range of data sources: notably (1) archaeological site surveys ( n = 32,000) and 14C dates ( n = 12,000) as proxies for long-term population change, (2) pollen records as a proxy for past vegetation and land cover ( n = 253) and (3) proxies, such as stable isotopes, from lake, cave and marine records as indicators of hydro-climate ( n = 47). Where possible, these data sets have been made spatially and temporally congruent in order to examine relationships between them statistically and graphically. Data have been aggregated or averaged for each region/sub-region and put into 200-year time windows. Archaeo-demographic data show a clear increase at the start of Neolithic farming, followed by a series of regionally asynchronous fluctuations in population, prior to a pan-Mediterranean Roman settlement maximum. Pollen data indicate a late-Holocene decline in %Arboreal Pollen in those regions that were initially well wooded, but not in drier regions of the southern/eastern Mediterranean. Overall, the clearest palynological proxy for human land cover change is provided by the OJCV (tree crop) index. The cultivation of these trees in the eastern Mediterranean after 6500 cal. yr BP may have been an adaptive response to mid-Holocene climatic desiccation. These anthropogenic pollen indicators correlate more closely with trends in population than with regional hydro-climatic z scores, implying that they reflect primarily human activities. During the mid Holocene, most Mediterranean landscapes were transformed by a combination of climate and rural land use, but after ~3500 cal. yr BP, human actions became increasingly dominant in determining land cover. During the past 1500 years, the dominant landscape trajectory in the eastern Mediterranean was markedly different to that in the central/western Mediterranean.

Significance This study reveals that animal fats preserved in pottery vessels from the United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage site of Çatalhöyük recorded the abrupt 8.2-thousand years B.P. climatic event in their hydrogen isotopic compositions. In addition, significant changes are observed in the archaeology and faunal assemblage of the site, showing how the early farming community at Çatalhöyük had to adapt to climate change. Significantly, this contribution shows that individual biomolecules preserved in ancient animal fats can be used to reconstruct paleoclimate records and thus, provides a powerful tool for the detection of climatic events at well-dated onsite terrestrial locations (i.e., at the very settlements where human populations lived)., The 8.2-thousand years B.P. event is evident in multiple proxy records across the globe, showing generally dry and cold conditions for ca. 160 years. Environmental changes around the event are mainly detected using geochemical or palynological analyses of ice cores, lacustrine, marine, and other sediments often distant from human settlements. The Late Neolithic excavated area of the archaeological site of Çatalhöyük East [Team Poznań (TP) area] was occupied for four centuries in the ninth and eighth millennia B.P., thus encompassing the 8.2-thousand years B.P. climatic event. A Bayesian analysis of 56 radiocarbon dates yielded a high-resolution chronological model comprising six building phases, with dates ranging from before 8325–8205 to 7925–7815 calibrated years (cal) B.P. Here, we correlate an onsite paleoclimate record constructed from δ2H values of lipid biomarkers preserved in pottery vessels recovered from these buildings with changes in architectural, archaeozoological, and consumption records from well-documented archaeological contexts. The overall sequence shows major changes in husbandry and consumption practices at ca. 8.2 thousand years B.P., synchronous with variations in the δ2H values of the animal fat residues. Changes in paleoclimate and archaeological records seem connected with the patterns of atmospheric precipitation during the occupation of the TP area predicted by climate modeling. Our multiproxy approach uses records derived directly from documented archaeological contexts. Through this, we provide compelling evidence for the specific impacts of the 8.2-thousand years B.P. climatic event on the economic and domestic activities of pioneer Neolithic farmers, influencing decisions relating to settlement planning and food procurement strategies.

Carbonates and diatoms are rarely deposited together in lake sediments in sufficient quantities for the oxygen isotope composition (δ18O) to be investigated simultaneously from both hosts. Here, δ18Ocarbonate are compared to δ18Odiatom data from the varved sediments of Nar Gölü, a closed lake in central Turkey, over the last 1710 years. Lake monitoring suggests carbonate is probably precipitated during May–June and δ18Ocarbonate is a proxy for regional water balance. Diatom activity is mainly weighted towards the spring. At times between ∼301 and 561 AD, while δ18Ocarbonate values are the highest for the entire 1710 year period, suggesting summer drought, δ18Ocorrected-diatom values are among the lowest. δ18Olakewater values estimated for the times of diatom growth and carbonate precipitation show large differences. We suggest this could be explained by increased snowmelt that formed a freshwater lid on the lake at the time of peak diatom growth. Increased snowmelt is also inferred ∼561–801 AD. From 801 AD to the present, precipitation is less winter-dominated, although increased snowmelt is inferred 921–1071 AD and in the latter part of the Little Ice Age (i.e. the mid to late 1800s AD). By combining oxygen isotope data from hosts that form in lakes at different times of the year, we show that such analyses can provide insights into palaeo-seasonality.

Detrital carbonate contamination is one of the principal problems with the integrity of stable isotope data from authigenic lake carbonates. Here we investigate the origin and climatic implications of stable isotope data from carbonate minerals deposited in two Mediterranean lakes: Golhisar Gl (SW Turkey) and Lake Pamvotis (NW Greece). In Golhisar Gl the bulk carbonate oxygen and carbon isotope composition has previously been interpreted in terms of significant climate variation related to the lake's hydrological balance. However, the origin of the carbonates was not investigated even though phases of high magnetic susceptibility suggest that there were several periods of increased soil erosion from the karstic catchment which could bring detrital limestone in to the lake. SEM evidence suggests that the carbonates in Golhisar Gl sediments of Holocene age are predominantly derived from forms of authigenic calcite (i.e. platelets, prismatic crystals), although periods of inwash clearly occurred which may have influenced parts of the isotope stratigraphy during the last two millennia. For comparison we also looked at data of Late Pleistocene to Holocene age from Lake Pamvotis. Here, there is an excellent correlation between the bulk carbonate oxygen isotope and magnetic susceptibility data, but no significant correlation between the bulk carbonate isotope data and ostracod isotope data from the same levels. SEM analyses confirmed the presence of detrital carbonates and the lack of significant authigenic carbonate. While the Glhisar record records aspects of climate in most of its isotope data, in the Pamvotis record only the ostracod data are likely to contain meaningful information.

Coupled multiproxy indicators (pollen, stable isotopes and charcoal) reconstructed from annually laminated lake sediments from Nar Gölü in Cappadocia (central Turkey) complemented by documentary and archaeological evidence provide a detailed record of environmental changes and their causes from late Antiquity (AD 300) to the present day. Stable isotope data indicate marked shifts in the variability in summer drought intensity and winter—spring rainfall, but these did not coincide in time with changes in vegetation and land use shown by pollen data. Rather, human impacts appear to have been the main driver of landscape ecological changes in Cappadocia over the last two millennia. Pollen and charcoal data indicate four principal land-use phases: (i) an early Byzantine agrarian landscape characterized by cereals and tree crops, and marking the later part of the so-called Beyşehir Occupation phase; (ii) a period of landscape abandonment and the establishment of secondary woodland from AD 670 to 950 coinciding with the Arab invasions of Anatolia and marking the transition from late Antiquity to the middle Byzantine period; (iii) the re-establishment of cereal-based agriculture and pastoralism from c. AD 950, with this cultural landscape being maintained through the Byzantine `Golden Age', the Seljuk and Ottoman Empires; and (iv) agricultural intensification during the late Ottoman era and the Turkish Republic (AD 1830 to present). Charcoal fluxes indicate that prior to the twentieth century, landscape burning was most frequent at times of diminished human impact when fuel biomass increased. Pollen and historical data show remarkably close agreement in terms of the timing of landscape change, and the former suggest that rural cultural traditions were able to survive largely intact through short-lived periods of socio-political dislocation such as the sixth century Justinian plague and the thirteenth century Mongol invasions.

There is a lack of high-resolution records of hydroclimate variability in the Eastern Mediterranean from the late glacial and early Holocene. More knowledge of the speed of climate shifts and the degree to which they were synchronous with changes in the North Atlantic or elsewhere is required to understand better the controls on Eastern Mediterranean climate. Using endogenic carbonate from a sediment sequence from Nar Golu, a maar lake in central Turkey, dated by varve counting and uranium-thorium methods, we present high-resolution (∼25 years) oxygen (δ18O) and carbon isotope records, supported by carbonate mineralogy data, spanning the late glacial and Holocene. δ18Ocarbonate at Nar Golu has been shown previously to be a strong proxy for regional water balance. After a dry period (i.e. evaporation far exceeding precipitation) in the Younger Dryas, the data show a transition into the relatively wetter early Holocene. In the early Holocene there are two drier periods that appear to peak at ∼9.3 ka and ∼8.2 ka, coincident with cooling ‘events’ seen in North Atlantic records. After this, and as seen in other records from the Eastern Mediterranean, there is a millennial-scale drying trend through the Mid Holocene Transition. The relatively dry late Holocene is punctuated by centennial-scale drought intervals, at the times of 4.2 ka ‘event’ and Late Bronze Age societal ‘collapse’. Overall, we show that central Turkey is drier when the North Atlantic is cooler, throughout this record and at multiple timescales, thought to be due to a weakening of the westerly storm track resulting from reduced cyclogenesis in the North Atlantic. However, some features, such as the Mid Holocene Transition and the fact the early Holocene dry episodes at Nar Golu are of a longer duration than the more discrete ‘events’ seen in North Atlantic records, imply there are additional controls on Eastern Mediterranean hydroclimate.

Lake Sonachi, Kenya, is a small alkaline-saline crater lake that over the past 175 years has experienced considerable fluctuations in lake depth ( Zmax 5 3‐18 m) and an alternation of meromictic and holomictic episodes lasting from a few years to several decades. Paleolimnological methods were used to reconstruct the long-term dynamics of algal and invertebrate communities in Lake Sonachi in relation to the historical evolution of their physical and chemical environment. Multivariate statistical analysis revealed only weak correlation between the stratigraphic distributions of fossil algal pigments, diatoms, and chironomid larvae in 210 Pb-dated sediment cores and the documented or reconstructed variation in lake depth, mixing regime, and surface-water conductivity. The eventful biological history of Lake Sonachi exemplifies the complexity of long-term community dynamics in tropical African soda lakes and reveals how phytoplankton community structure can exert direct control on benthic and planktonic invertebrate communities. The modest phytoplankton abundance and photosynthetic activity of Lake Sonachi when compared with other tropical African soda lakes represent recent lake conditions, resulting from a dramatic decline of filamentous cyanobacteria (e.g., Spirulina platensis) between the 1930s and 1970s and incomplete replacement by the small coccoid cyanobacteria (e.g., Synechococcus bacillaris), which are dominant today. This reduction in algal biomass favored benthic and planktonic invertebrates by reducing the prevalence of complete water-column anoxia associated with intense nighttime respiration of cyanobacterial blooms. Anoxia-intolerant halobiont chironomids expanded during an episode of low lake level (Zmax , 4 m), holomixis, and high conductivity (.9,000 m Sc m 21 ) in the late 1940s and 1950s, whereas they had failed to do so under similar conditions in the late 19th century when algal abundance was high. Planktonic cladocerans developed high population densities only during two short meromictic phases in the 1970s when conductivity was modest (3,000‐6,000 m Sc m 21 ) and algal abundance was low. The decline of filamentous cyanobacteria also increased water-column transparency but apparently did not increase benthic diatom abundance.

An abrupt cold event ca. 8200 cal. yr BP, is believed to have been caused by the catastrophic release of ice-dammed meltwater from Lake Agassiz and associated disruption of the Atlantic Meridional Overturning Circulation (AMOC). Previous reviews have highlighted both the “ideal” nature of the 8200 yr event as a target for numerical model validation and the likely geographical restriction of the ensuing cold event to the circum-North Atlantic region but have cited a lack of sufficiently resolved palaeoclimatic records to test this hypothesis. We review the current set of high-resolution stable isotope records from multiple archives (lake, bog, marine and ice cores) in the North Atlantic region for the period 9200–7400 yr BP (present = AD 1950). The isotopic values of terrestrial records are closely linked to isotopic values of palaeoprecipitation. All sites provided evidence for at least one centennial-scale anomaly (beginning ~ 8500–8250 yr BP) that exceeded background variability. No evidence for spatial or temporal transgression of the isotope anomalies was identified, implying that a simultaneous climate signal was observed in the circum-North Atlantic region. Comparison with new simulations using the UK Hadley Centre model HadCM3, which was isotope-enabled to simulate changes in the stable isotope composition of precipitation and forced by freshwater input (“hosing”) of 5 Sverdrups (Sv) (0.005 km3/s), for 1 yr, indicated agreement with the observed decrease in the amplitude of the isotope anomaly with distance from the NW North Atlantic. The model-simulated duration of the event, however, was consistently shorter than that observed in palaeoclimatic records. A review of evidence for forcing additional to the catastrophic release of meltwater from Lake Agassiz (solar variability, sea-ice feedback and longer-term meltwater history) suggested that reduced solar output did not directly coincide with the 8200 yr event, but that a more complex history of meltwater discharges and sea-ice feedback may have conditioned the AMOC for sustained climatic impact.

Oxygen isotopes provide one of the best tracers of the Mediterranean hydrological cycle from source areas in the oceans, through precipitation, to ground- and surface freshwaters. The ratio of oxygen isotopes preserved in sedimentary carbonates also provides a key indicator of natural climatic variability over timescales beyond those based on direct monitoring or historical observations. This set of papers, originally deriving from an ESF MedClivar workshop meeting in Pisa, Italy, critically considers how δ18O data can be used to provide records of Mediterranean climate variability over a hierarchy of timescales. They focus on five main themes, namely 1) water isotopes as tracers for monitoring and modelling patterns of precipitation, 2) lakes and surface waters, and their sedimentary records, 3) groundwaters and cave systems as preserved in speleothems, 4) marine systems, such as deep-sea sediments and surface corals, and 5) intercomparison of different archives and regional-scale data: model comparisons using isotope data bases. Future priorities include improved calibration of proxy-climate data via monitoring of contemporary systems and mass balance modelling, and a focus on synthesising high-resolution climate reconstructions during the last 2000 years.

Oxygen isotope records from lake sediment archives are becoming an increasingly common tool for palaeoenvironmental reconstruction. We discuss their interpretation in the Eastern Mediterranean region with particular reference to three records, Zeribar, Van and Eski Acıgöl during the Holocene. The latter two records have been interpreted as controlled by changes in the precipitation to evaporation ratio, and the first due to changes in precipitation seasonality. In light of recent isotope work in the region and comparison with other proxy data from the same lakes, we show both of these initial interpretations to be oversimplified. Careful interpretations of complex lake isotope systems are therefore required in order that palaeoclimatic inferences are drawn correctly.

A high resolution proxy record of precipitation and evaporation variability through the past 1700 yr from δ18O analysis of a varved lake sequence from central Turkey shows rapid shifts between dry periods (AD 300–500 and AD 1400–1950) and wetter intervals (AD 560–750 and AD 1000–1350). Changes are consistent with changes in instrumental and proxy records of the Indian monsoon, dry summers in the Eastern Mediterranean being associated with periods of enhanced monsoon rainfall. In addition major shifts in the record are coherent with changes in North Atlantic winter climate with cold, wet periods in the Alps occurring at times of dry Turkish climate.

Comparisons between climate proxies and instrumental records through the last two centuries are often used to understand better the controls on palaeoarchives and to find relationships that can be used to quantify changes in pre-instrumental climate. Here we compare an 80-year-long annually resolved oxygen isotope record from Nar Golu, Turkey, a varved lake sequence, with instrumental records of temperature, precipitation, wind speed, relative humidity and calculated values of evaporation, all of which are known to be possible controls on lake oxygen isotope systems. Significant relationships are found between the isotope record and summer temperatures and evaporation suggesting these are dominant controls on the isotope hydrology of this non-outlet lake. Modelling the stable isotope hydrology of the lake system allows these relationships to be tested independently. We show that the isotope record follows the same trends in the temperature and evaporation records but that, even when combined, these two climatic factors cannot fully explain the magnitude of change observed in the isotope record. The models show the lake system is much less sensitive to changes in evaporation and temperature than the climate calibration suggests. Additional factors, including changes in the amount of precipitation, are required to amplify the isotope change. It is concluded that proxy-climate calibrations may incorrectly estimate the amplitude of past changes in individual climate parameters, unless validated independently.

The zonal climate pattern associated with the Hadley cell circulation is best exemplified in northern Africa, with its Mediterranean northern tip, subtropical Sahara desert, and belts of monsoonal and equatorial climates related to the seasonal migration of the Intertropical Convergence Zone (ITCZ). In the past, astronomical forcing has been the prime factor driving the meridional shifts of these climate belts, but feedback processes from oceans and land surfaces have amplified and modified the direct effects of insolation changes.