High resolution Late-glacial and early-Holocene summer air temperature records from Scotland inferred from Chironomid assemblages

Lateglacial and early-Holocene mean July air temperatures have been reconstructed, using a chironomid-based inference model, from lake-sediment sequences from Abernethy Forest, in the eastern Highlands of Scotland, and Loch Ashik, on the Isle of Skye in north-west Scotland. Chronology for Abernethy Forest was derived from radiocarbon dates of terrestrial plant macrofossils deposited in the lake sediments. Chronology for Loch Ashik was derived from tephra layers of known ages, the first age-depth model of this kind. Chironomid-inferred temperatures peak early in the Lateglacial Interstadial and then gradually decline by about 1 °C to the beginning of the Younger Dryas (YD). At Abernethy Forest, the Lateglacial Interstadial is punctuated by three centennial-scale cold oscillations which appear to be synchronous with the Greenland Interstadial events GI-1d, when temperatures at Abernethy fell by 5.9 °C, GI-1c, when temperatures fell by 2.3 °C, and GI-1b, when temperatures fell by 2.8 °C. At Loch Ashik only the oscillation correlated with GI-1d is clearly defined, when temperatures fell by 3.8 °C. The start of the YD is clearly marked at both sites when temperatures fell by 5.5 °C at Abernethy Forest and 2.8 °C at Loch Ashik. A warming trend is apparent during the late-YD at Abernethy Forest but at Loch Ashik late-YD temperatures became very cold, possibly influenced by its close proximity to the Skye ice-field. The rapidly rising temperatures at the YD – Holocene transition occur about 300 years earlier at both sites than changes in sediment lithology and loss-on-ignition. The temperature trends at both sites are broadly similar, although between-site differences may result from the influence of local factors. Similar climate trends are found at other sites in the northern British Isles. However, the British summer temperature records differ in detail from trends in the oxygen-isotope records from the Greenland ice-cores and from other chironomid-inferred temperature records available from Scandinavia, north-west Europe and central Europe, which suggest important differences in the influence of climatic forcing at regional scales.publishedVersio

A guide to the processing and standardization of global palaeoecological data for large-scale syntheses using fossil pollen

Aim: Palaeoecological data are crucial for comprehending large-scale biodiversity patterns and the natural and anthropogenic drivers that influence them over time. Over the last decade, the availability of open-access research databases of palaeoecological proxies has substantially increased. These databases open the door to research questions needing advanced numerical analyses and modelling based on big-data compilations. However, compiling and analysing palaeoecological data pose unique challenges that require a guide for producing standardized and reproducible compilations. Innovation: We present a step-by-step guide of how to process fossil pollen data into a standardized dataset compilation ready for macroecological and palaeoecological analyses. We describe successive criteria that will enhance the quality of the compilations. Though these criteria are project and research question-dependent, we discuss the most important assumptions that should be considered and adjusted accordingly. Our guide is accompanied by an R-workflow—called FOSSILPOL—and corresponding R-package—called R-Fossilpol—that provide a detailed protocol ready for interdisciplinary users. We illustrate the workflow by sourcing and processing Scandinavian fossil pollen datasets and show the reproducibility of continental-scale data processing. Main Conclusions: The study of biodiversity and macroecological patterns through time and space requires large-scale syntheses of palaeoecological datasets. The data preparation for such syntheses must be transparent and reproducible. With our FOSSILPOL workflow and R-package, we provide a protocol for optimal handling of large compilations of fossil pollen datasets and workflow reproducibility. Our workflow is also relevant for the compilation and synthesis of other palaeoecological proxies and as such offers a guide for synthetic and cross-disciplinary analyses with macroecological, biogeographical and palaeoecological perspectives. However, we emphasize that expertise and informed decisions based on palaeoecological knowledge remain crucial for high-quality data syntheses and should be strongly embedded in studies that rely on the increasing amount of open-access palaeoecological data.publishedVersio

Macrofossils in Raraku Lake (Easter Island) integrated with sedimentary and geochemical records: Towards a palaeoecological synthesis for the last 34,000 years

Macrofossil analysis of a composite 19m long sediment core from Rano Raraku Lake (Easter Island) wasrelated to litho-sedimentary and geochemical features of the sediment. Strong stratigraphical patterns are shown by indirect gradient analyses of the data. The good correspondence between the stratigraphical patterns derived from macrofossil (Correspondence Analysis) and sedimentary and geochemical data (Principal Component Analysis) shows that macrofossil associations provide sound palaeolimnological information in conjunction with sedimentary data. The main taphonomic factors influencing the macrofossil assemblages are run-off from the catchment, the littoral plant belt, and the depositional environment within the basin. Five main stages during the last 34,000 calibrated years BP (calyrBP) are characterised from the lithological, geochemical, and macrofossil data. From 34 to 14.6calkyrBP (last glacial period) the sediments were largely derived from the catchment, indicating a high energy lake environment with much erosion and run-off bringing abundant plant trichomes, lichens, and mosses into the centre of Raraku Lake. During the early Holocene the infilling of the lake basin and warmer conditions favoured the growth of a littoral plant belt that obstructed terrigenous input. Cladoceran remains and Solanaceae seeds are indicative of reduced run-off and higher values of N and organic C indicate increased aquatic and catchment productivity. From 8.7 to 4.5calkyrBP a swamp occupied the entire basin. The increase of Cyperaceae seeds reflects this swamp development and, with oribatid mites and coleopteran remains, indicates a peaty environment and more anoxic conditions in Raraku. At around 4.5calkyrBP dry conditions prevented peat growth and there is a sedimentary hiatus. About 800calyrBP, peat deposition resumed. Finally, in the last few centuries, a small lake formed within the surrounding swamp. Evidence of human activity is recorded in these uppermost sediments. © 2011 Elsevier Ltd.This research was funded by the Spanish Ministry of Science and Education through the projects LAVOLTER (CGL2004-00683/BTE), GEOBILA (CGL2007-60932/BTE) and CONSOLIDER GRACCIE (CSD2007-00067) and an undergraduate grant (BES-2008-002938 to N. Cañellas-Boltà).Peer Reviewe

Did the Eurasian ice sheets melt completely in early Marine Isotope Stage 3? New evidence from Norway and a synthesis for Eurasia

We describe glaci-lacustrine sediments buried under thick tills in Folldalen, south-east Norway, a site located close to the former centre of the Scandinavian Ice Sheet. Thus, the location implies that the ice sheet had melted when the sediments were deposited. The exposed ground was occupied by arctic vegetation. The best age estimate from 20 quartz luminescence dates is 55.6 ± 4.6 ka. Due to possible incomplete bleaching, an age in the younger part of the time range is most probable. We conclude that the Scandinavian Ice Sheet melted almost completely away early in Marine Isotope Stage (MIS) 3. Our review shows that the other Eurasian ice sheets also disappeared in that period. In north-western Germany, there were forests, containing warmth-demanding trees early in MIS 3, indicating a summer climate only slightly cooler than at present, thus supporting the evidence that the adjacent ice sheets had melted. The melting of the Eurasian ice sheets contributed to 50–100% of the sea-level rise from MIS 4 to MIS 3, implying that the much larger North American ice sheets did not melt much. In contrast, the Eurasian ice sheets contributed only about 30% to the sea-level drop from MIS 3 to MIS 2, meaning that the North American ice sheets during that period expanded strongly.publishedVersio

Exploring spatio-temporal patterns of palynological changes in Asia during the Holocene

Historical legacies influence present-day ecosystem composition and dynamics. It is therefore important to understand the long-term dynamics of ecosystems and their properties. Analysis of ecosystem properties during the Holocene using fossil pollen assemblages provides valuable insights into past ecosystem dynamics by summarising so-called pollen-assemblage properties (PAPs). Using 205 fossil pollen data-sets (records), we quantify eight PAPs [pollen-taxonomic richness, diversity, evenness, pollen-compositional turnover, pollen-compositional change, and rate of pollen-compositional change (RoC)] for the Asian continent at different spatial scales (in individual records, within and across climate-zones, and within the continent) and time (temporal patterns over the past 12,000 years). Regression tree (RT) partitioning of the PAP-estimates using sample-age as a sole predictor revealed the “change-point(s)” (time or sample-age of major change in a PAP). We estimated the density of RT and multivariate regression tree (MRT) change-points in 1,000-year time bins during the Holocene. Pollen-compositional turnover (range of sample scores along the first DCCA axis) and change (number of MRT partitions) in each record reveal gradual spatial variation across latitude and a decline with longitude eastward. Temporally, compositional turnover declines linearly throughout the Holocene at all spatial scales. Other PAPs are heterogeneous across and within spatial scales, being more detectable at coarser scales. RT and MRT change-point density is broadly consistent in climate-zones and the continent, increasing from the early- to mid-Holocene, and mostly decrease from the mid-Holocene to the present for all PAPs. The heterogenous patterns in PAPs across the scales of study most likely reflect responses to variations in regional environmental conditions, anthropogenic land-use, and their interactions over space and time. Patterns at the climate-zone and continental scales indicate a gradual but congruent decline in major PAPs such as compositional turnover, rate of compositional change, and major temporal compositional changes (MRT) during the Holocene, especially during recent millennia, suggesting that vegetation in Asia has become progressively more homogenous. Data properties (e.g., spatial distribution of the records, distribution of samples within the records, and data-standardisation and analytical approaches) may also have partly influenced the results. It is critically important to evaluate the data properties and the approaches to data standardisation and summarisation.publishedVersio

Approaches to pollen taxonomic harmonisation in Quaternary palynology

Pollen taxonomic harmonisation involves the standardisation of the nomenclature of pollen and fern spores with similar morphotypes at the determination level that is common to all grains or spores with that morphotype within the pollen sequence(s) of interest. Such harmonisation is required prior to subsequent investigations such as numerical analysis, comparing, mapping, synthesis, and environmental reconstruction involving several pollen sequences. Here we present two approaches to harmonisation. These are a ‘top-down’ and a ‘bottom-up’ approach. The bottom-up approach is preferred. It is based on the concept of the regional pollen flora for the sequence(s) in the spatial area(s) of study. We present bottom-up harmonisation tables for the continental or sub-continental scales developed for the Humans on Planet Earth (HOPE) project. The tables are for North America, Latin America, Europe, Asia (three parts), and Indo-Pacific. These harmonisations are project-specific and sequence-specific, relating to the geographical area and to the sequences in the area under consideration, both of which are linked to the research questions being addressed. A new bottom-up harmonisation with a consistent taxonomic level and nomenclature is needed when additional sequences or areas are added. However, the HOPE tables can serve as a starting point for further research involving multi-sequence analyses or syntheses.publishedVersio

Holocene treeline and timberline changes in the South Carpathians (Romania): Climatic and anthropogenic drivers on the southern slopes of the Retezat Mountains

Two high-altitude lake-sediment sequences (Lake Lia, 1910 m a.s.l. and Lake Bucura, 2040 m a.s.l.) from the Retezat Mountains (South Carpathians, Romania) were analysed using multi-proxy methods to study responses of treeline, timberline and alpine/subalpine vegetation to climate change and human impact during the past 16,000 years. Woody species (Pinus mugo, Pinus cembra, Picea abies and Juniperus communis) reached Lake Lia between 12,000 and 11,800 cal. yr BP, whereas P. mugo colonised the shores of Lake Bucura at 9600 cal. yr BP. Lake Lia was in the timberline ecotone between 8000 and 3200 cal. yr BP, in semi-open P. cembra and Picea abies woodland, probably mixed with P. mugo on the steeper slopes. Lake Bucura was surrounded by the upper part of the krummholz zone during the mid-Holocene. The increase in P. cembra after c. 6000 cal. yr BP around Lake Lia suggests that the composition of the timberline forest changed. The disappearance of P. cembra and Picea abies around Lake Lia at ~3000 cal. yr BP reflects descent of the timberline. A large mean July temperature decline between 3300 and 2800 cal. yr BP may have driven or at least contributed to the descent of the Picea abies?P. cembra forests. An increase in human indicator pollen types in Lake Bucura around 4200 cal. yr BP may reflect human impact in the naturally open alpine zone in the Late Bronze Age. In contrast, human impact likely appeared considerably later, around 2650 cal. yr BP (Early Iron Age) around Lake Lia in the upper subalpine zone. Human impact likely intensified after 2200 cal. yr BP at both sites that resulted in the lowering of the krummholz zone. We conclude that climate change and human impact both played an important role in the lowering of the treeline and timberline in the late-Holocene

Holocene fire-regime changes near the treeline in the Retezat Mts. (Southern Carpathians, Romania)

To investigate Holocene vegetation and fire-disturbance histories in the treeline ecotone, macroscopic charcoal, plant-macrofossil, and pollen records from two lacustrine sediment records were used. Lake Lia is on the southern slope and Lake Brazi is on the northern slope of the west-east-oriented Retezat Mountain range in the Romanian Carpathians. The records were used to reconstruct Holocene fire-return intervals (FRIs) and biomass burning changes. Biomass burning was highest at both study sites during the drier and warmer early Holocene, suggesting that climate largely controlled fire occurrence. Fuel load also influenced the fire regime as shown by the rapid biomass-burning changes in relation to timberline shifts. Overall, the number of inferred fire episodes was smaller on the northern than on the southern slope. FRIs were also comparatively longer (1000-4000 years) on the northern slope where Picea abies-dominated woodlands persisted around Lake Brazi throughout the Holocene. On the southern slope, where Pinus mugo was more abundant around Lake Lia, FRIs were significantly shorter (80-1650 years). A period of frequent fire episodes occurred around 1900-1300 cal yr BP on the southern slope, when chironomid-inferred summer temperatures increased and the pollen record documents increased anthropogenic activity near the treeline. However, the forest clearance by burning to increase grazing land was subdued in comparison to other European regions. © 2016 Elsevier Ltd and INQUA

European Code against Cancer 4th Edition:Obesity, body fatness and cancer

AbstractIt is estimated that over half the population of the European Union (EU) is overweight or obese due to an imbalance between energy expenditure and energy intake; this is related to an obesogenic environment of sociocultural, economic and marketing challenges to the control of body weight. Excess body fat is associated with nine cancer sites – oesophagus, colorectum, gall bladder, pancreas, postmenopausal breast, endometrium, ovary, kidney and prostate (advanced) – and 4–38% of these cancers (depending on site and gender) can be attributed to overweight/obesity status. Metabolic alterations which accompany excess body weight are accompanied by increased levels of inflammation, insulin, oestrogens and other hormonal factors. There are some indications that intentional weight loss is associated with reduced cancer incidence (notably in postmenopausal breast and endometrial cancers). Excess body weight is also a risk factor for several other diseases, including diabetes and heart disease, and is related to higher risk of premature death.In reviewing the current evidence related to excess body fat and cancer, the European Code against Cancer Nutrition Working Group has developed the following recommendation: ‘Take action to be a healthy body weight’