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Evidence of past glacier fluctuations is valuable palaeoenvironmental data, but determining their relationship to climatic change is sometimes complex because of differing glacier sensitivities and patterns of response. In Iceland, a diverse range of glaciation creates changing geographical patterns of response to climatic changes. The outlet glaciers of the Mardalsjokull ice cap in southern Iceland have produced detailed, but differing, records of change. For a key southwestern sector of the ice cap, we specifically searched for evidence equivalent to the c. 4500 BP, c. 3100 BP and c. 1200 BP advances of Solheimajokull reported earlier. A combination of geomorphological mapping and dating by tephrochronology and lichenometry was used to constrain the glacier advances and determine the relative magnitude of Neoglacial glacier episodes. This is a key step towards creating a record of the changes for the entire ice cap. Major glacier advances c. 4500–1000 BP previously identified on the southern margin of Mardalsjokull are shown not to have occurred in this sector, where Neoglacial maxima occur post-1755 AD.

Moraine ridges are commonly used to identify past glacier ice margins and so infer glacier mass balance changes in response to climatic variability. However, differences in the form of past ice mar...

Summary 1Conceptual models of ecosystem development commonly predict a phase of initial colonization characterized by the nucleation, growth and coalescence of discrete patches of pioneer plants. Spatiotemporal dynamics during subsequent development may follow one of three different models: the classical model, in which initially discrete patches of competitive dominant (secondary) colonists coalesce to form a homogeneous cover; the patch dynamics model, in which renewal mechanisms such as disturbance create a shifting mosaic of patches at different stages; and the geoecological model, in which the vegetation gradually differentiates along edaphic gradients related to the underlying physical template. 2These models of spatiotemporal dynamics were tested using vegetation and soil data from an 850-year chronosequence, comprised of seven lava flows on Mt Hekla, Iceland. The scale and intensity of spatial pattern were quantified on each flow using spatial analyses (mean-variance ratios, quadrat variance techniques and indices of autocorrelation). Changes in spatial pattern with increasing terrain age were compared with predicted trajectories, in order to identify which of the models of spatiotemporal dynamics was most consistent with the observations. 3The early stages of ecosystem development were characterized by colonization of the pioneer species, especially Racomitrium mosses, in discrete patches (‘Pioneer colonization stage’, 600 years). 4Synthesis. The spatiotemporal dynamics observed in the early stages of this succession were consistent with a model of pioneer nucleation in micro-scale safe sites, followed by growth, coalescence and eventual fragmentation of pioneer patches. The spatial patterns which emerged later in development support the geoecological model, with spatial differentiation of vegetation related to meso-scale substrate topography. The findings provide insight on how vegetation patterns emerge at different stages of ecosystem development in response to differing scales of heterogeneity in the underlying physical environment.

Questions: How does vegetation first establish on newly-formed lava substrates? Do very small (cm) and meso-scale (m) variations in the physical environment influence this process and subsequent vegetation development? Location: Mount Hekla, southern Iceland (64°00′ N, 19°40′ W). Methods: Data on vegetation structure and the incidence of ‘safe sites’ suitable for colonisation were collected from high and low points on the surfaces of lava flows emplaced during the 1991 and 2000 A.D. eruptions of Mount Hekla. Effects of flow age and meso-topographic position on vegetation structure (moss cover, patch density, stem length) were assessed by two-way analyses of variance. The distributions of colonisation events and available safe sites were analysed using point pattern techniques. Results: Rapid colonisation of the lava surface was observed, despite stressful environmental conditions. The 1991 and 2000 flows differed significantly in vegetation structure, but there were no significant differences in ...

The origins of the Icelandic biota are discussed with particular reference to recent work on Coleopteran (beetle) and Trichopteran (caddis fly) fossils from deposits which are earlier than the arrival of man (Landnam) in the country. The hypothesis of survival through Pleistocene glaciations in refugia is discounted in favour of immigration on ice floes during Late Glacial/Early Holocene deglaciation. Consideration of the nature of the insect fauna and the extent of Late Glacial ice sheets, with the evidence from ocean circulation patterns, suggests a source area in the fjords of south-west Norway. The model is applicable to the origins of the biota on all the North Atlantic islands, east of the Davis Strait.

Ice-divide migration may explain the pattern of Holocene glacier fluctuations around the Mýrdalsjokull ice cap in southern Iceland. On at least three occasions Solheimajokull, the principal outlet glacier on the southwest flank of the ice cap, has exceeded the Little Ice Age limits of recent centuries that mark the maximum extent of neighbouring glaciers in the Holocene. Bedrock divides beneath the Mýrdalsjokull ice cap do not coincide with present ice divides. It is suggested that the ice divide migrated during the course of ice-cap growth. At various stages during the Holocene (7000-4500, c. 3100, 1400-1200 BP) Solheimajokull could have drained more of the ice cap than today, so becoming more advanced than neighbouring glaciers. In the Little Ice Age (c. AD 1600–1900) the glacier could have had a smaller catchment as a result of ice-divide migration, resulting in a more inhibited advance compared with neighbouring glaciers which reached their Holocene maximum at that time. Identification of ice-divide migration is important for palaeoclimatic reconstructions because of the need to recognize different responses of glaciers to climate if one is to use their fluctuations as indicators of change.

Significance Climate-induced disasters are impacting human well-being in ever-increasing ways. Disaster research and management recognize and emphasize the need to reduce vulnerabilities, although extant policy is not in line with this realization. This paper assesses the extent to which vulnerability to food shortage, as a result of social, demographic, and resource conditions at times of climatic challenge, correlates with subsequent declines in social and food security. Extreme climate challenges are identified in the prehispanic US Southwest and historic Norse occupations of the North Atlantic Islands. Cases with such different environmental, climatic, demographic, and cultural and social traditions allow us to demonstrate a consistent relationship between vulnerability and consequent social and food security conditions, applicable in multiple contexts.

This research was funded by the Commonwealth Scholarship Commission and received support from the Research Budget of the Department of Archaeology at the University of Aberdeen. This project was undertaken as part of doctoral studies supervised by Dr Karen Milek, to whom V.F. is especially grateful for her support and advice. Thomas Birch, Sigrun Inga Garðarsdottir, and Paul Ledger provided invaluable assistance during fieldwork. V.F. would like to dedicate this paper to Tom and Sia, who met during this fieldwork and are getting married this year. Many people from Fornleifastofnun Islands – Garðar Guðmundsson, Olof Þorsteinsdottir, Þora Petursdottir, Adolf Friðriksson and Uggi AEvarsson – as well as Unnstein Ingason, Agusta Edwald, and Mark Young, helped with fieldwork logistics. Special thanks are due to all the Icelandic farmers and their families who kindly allowed us to collect insects on their farms and provided help when needed: Hermann Aðalsteinsson, Hermina Fjola Ingolfsdottir, Guðmundur Skulason, Sigrun A. Franzdottir, Duna Magnusdottir, Sverrir Steinbergsson, Valgeir Þorvaldsson, Reynir Sveinsson, Jonas Þor Ingolfsson, and Ivar Olafsson. Eva Panagiotakopulu, Jan Klimaszewski, Ales Smetana, Georges Pelletier, Gabor Pozsgai, and Jenni Stockham helped with some of the beetle identifications. A.J.D. acknowledges the support of National Science Foundation through ARC 1202692. Consultation of the BugsCEP database (Buckland & Buckland, 2006) aided the redaction of this paper. The authors would like to thank David Smith and two anonymous reviewers for insightful comments that helped improve the quality of this paper.

This work was funded by the Leverhulme Trust under the programme ‘Landscapes circum-landnam’

We present a new climate and vegetation model, and discuss applications with a study of medieval land degradation and settlement abandonment in þorsmork, Iceland. Existing meteorological data are used as the starting point for modelling glacier snowlines (equilibrium lines), and this is developed to model seasonal snowcover, potential vegetation and growing season. The current status and past fluctuations of glaciers across Iceland provide independent spatial and temporal constraints to the model. In þorsmork, there was extensive landscape degradation and settlement abandonment in the late Medieval period, with an unclear role for climate change. Modelling of the landscape impacts of a 1 °C fall in temperatures shows that climatically induced degradation through reduced vegetation, growing season, and increased snowcover had limited effects on the once settled area, highlighting the importance of anthropogenically driven change. High resolution modelling offers a significant potential for assessing ‘what if’ questions, and identifying key empirical tests.

The marine reservoir effect (MRE) is a 14 C age offset between the oceanic and atmospheric carbon reservoirs. The MRE is neither spatially nor temporally constant and values may deviate significantly from the global model average provided by the Marine04 curve. Such a deviation is calculated as a Δ R value and modern (pre-bomb) values show considerable spatial variations. There is also considerable evidence for temporal variability linked to paleoenvironmental changes identified in paleoclimatic proxy records. Seven new Δ R values are presented for the North Atlantic, relating to the period c. 8430–3890 cal. BP (c. 6480–1940 BC). These were obtained from 14 C analysis of multiple samples of terrestrial and marine material derived from seven individual archaeological deposits from Mainland Scotland, the Outer Hebrides and the Orkney Isles. The Δ R values vary between 143 ± 20 14 C yr and −100 ± 15 14 C yr with the positive values all occurring in the earlier period (8430–5060 cal. BP), and the negative values all coming from later deposits (4820–3890 cal. BP). The nature of MRE values and the potential for spatial and temporal variation in values is the subject of current research interest and these data are placed in the context of (i) other estimates for UK coastal waters and (ii) important questions concerning current approaches to quantifying the MRE.

This paper examines 2 potential sources of the radiocarbon offset between human and terrestrial mammal (horse) bones recovered from Norse (∼AD 870–1000) pagan graves in Mývatnssveit, north Iceland. These are the marine and freshwater 14C reservoir effects that may be incorporated into human bones from dietary sources. The size of the marine 14C reservoir effect (MRE) during the Norse period was investigated by measurement of multiple paired samples (terrestrial mammal and marine mollusk shell) at 2 archaeological sites in Mývatnssveit and 1 site on the north Icelandic coast. These produced 3 new δR values for the north coast of Iceland, indicating a δR of 106 ± 10 14C yr at AD 868–985, and of 144 ± 28 14C yr at AD 1280–1400. These values are statistically comparable and give an overall weighted mean δR of 111 ± 10 14C yr.The freshwater reservoir effect was similarly quantified using freshwater fish bones from a site in Mývatnssveit. These show an offset of between 1285 and 1830 14C yr, where the fish are depleted in 14C relative to the terrestrial mammals. This is attributed to the input of geothermally derived CO2 into the groundwater and subsequently into Lake Mývatn. We conclude the following: i) some of the Norse inhabitants of Mývatnssveit incorporated non-terrestrial resources into their diet that may be identified from the stable isotope composition of their bone collagen; ii) the MRE off the north Icelandic coast during the Norse period fits a spatial gradient of wider North Atlantic MRE values with increasing values to the northwest; and iii) it is important to consider the effect that geothermal activity could have on the 14C activity of samples influenced by groundwater at Icelandic archaeological sites.

The first stratigraphically continuous pollen profile spanning the Norse and Medieval periods from the archaeologically-rich My´vatnssveit region of northern Iceland is presented. Detailed analyses were made of the tephra, sediment characteristics, pollen and chironomids of a 3 kyr sediment sequence from Helluvaðstjo¨ rn, a small, shallow lake. The pollen data show a steady decline in the percentage abundance of tree birch (Betula pubescens) pollen between the Norse settlement (landna´m, c. AD 870) and c. AD 1300, a pattern that contrasts with the abrupt fall in birch pollen percentages immediately following the Norse colonization at almost all previously studied sites in Iceland. Some lines of evidence suggest that the gradual birch decline could be a result of reworking of soil pollen, but independent evidence suggests that this may not necessarily be the case. The pollen record indicates that birch woodland was replaced by acidophilic taxa (notably Empetrum nigrum and Sphagnum), again contrasting with the more usual pattern of Poaceae expansion seen in post-landna´m pollen diagrams from mires close to farm sites. Chironomid and Pediastrum accumulation data show that the limnic environment became more productive immediately after landna´m, probably because of anthropogenic disturbance. An increase in sedimentation rate after landna´m appears initially to have been caused by increased lake productivity, while reworked inorganic soil materials became a significant contributor to the sediments after c. AD 1200. The data suggest that the impact of settlement on terrestrial vegetation may have been more variable than previously thought, while freshwater ecosystems experienced significant and rapid change.

Tephrabase was launched on the World Wide Web in 1995 as a tool for tephrochro- nological research. In order to facilitate the identification, correlation and dating of tephra deposits, this database may be interrogated through multiple routes, including by source volcano, date, location, and tephra chemistry; datasets include stratigraphy, geochemistry, chronology and spatial information. Currently all the European data refer to Late Quaternary Icelandic-sourced tephras, post- 12 k yr BP. The sites (62) where the tephra deposits are found include Iceland, the United Kingdom, Ireland, the Faroe Islands, Sweden and Russia. In addition, there are also data on tephra layers in central Mexico. Use of Tephrabase highlights the importance of selected geochemical data, but this has to be used with care as major element characteristics alone do not always produce unique definitions for single tephra deposits. For the most accurate results multiple criteria must be used. Tephrabase can be found at http://www.tephrabase.org. Copyright # 2007 John Wiley & Sons, Ltd.

Timber procurement and the use of woodlands are key issues in understanding the open landscapes of the Norse and Medieval periods in the North Atlantic islands. This paper outlines evidence for the timing and mechanisms of woodland use and deforestation in an area of southern Iceland, which is tracked through the mapping and analysis of charcoal production pits. Precise dating of the use of these charcoal production pits within a Bayesian framework is demonstrated through the combination of tephrochronology, sediment accumulation rates, and multiple radiocarbon dates on the archaeological charcoal. Two phases of charcoal production and woodland exploitation have been demonstrated, the first within the first 2 centuries of settlement (cal AD 870–1050) and the second phase over 100 yr later (cal AD 1185–1295). The implications for using charcoal as a medium for 14C dating in Iceland and the wider North Atlantic are then explored. Archaeobotanical analysis of the charcoal sampled from the pits has indicated that birch roundwood was the dominant wood used, that the roundwood was stripped from larger shrubs/trees in late spring/early summer, and that certain sizes and ages of roundwood were harvested. Finally, the timing of the charcoal production is placed into the wider debate on deforestation across Iceland during the Norse and early Medieval periods.

Geomorphological maps and nine soil profi les containing 92 tephra layers have been examined to explore the nature of medieval environmental change in fijorsardalur, Iceland, where farms are thought to have been abandoned after the massive tephra fall from the eruption of Hekla in 1104 A.D. This paper presents evidence for continued human activity in the area in the two centuries following the 1104 A.D. eruption, indicating that continued utilization of the region changed after another major episode of volcanic fallout in 1300 A.D. The paper proposes that measures were taken in the fourteenth century to conserve woodland in fijorsardalur result- ing in localized landscape stabilization that continued throughout the following Little Ice Age episodes of climate deterioration.

This study was financially supported by the Carnegie Trust for the Universities of Scotland, the National Science Foundation of America (through grant 1202692 ‘Comparative Island Ecodynamics in the North Atlantic’ and grant 1249313 ‘Tephra layers and early warning signals for critical transitions’) and the Leverhulme Trust (Study Abroad Fellowship to AJD). Pre-industrial human impacts on the past environment are apparent in different proxy records at different times in different places. Recognizing environmentally transformative human impacts in palaeoenvironmental archives, as opposed to natural variability, is a key challenge in understanding the nature of the transition to the Earth’s current ‘Anthropocene’ condition. Here, we consider the palaeoenvironmental record for Iceland over the past 2.5 ka, both before and after the late ninth century human settlement (landnám). The Scandinavian colonization of the island was essentially abrupt, involving thousands of people over a short period. The colonization triggered extensive changes in Icelandic ecosystems and landscapes. A volcanic ash known as the Landnám tephra was deposited over most of Iceland immediately before the settlement began. The Landnám tephra layer thus provides a uniquely precise litho-chrono-stratigraphic marker of colonization. We utilize this marker horizon as an independent definition of the effective onset of the local palaeoanthropocene (which is conceptually related to, but distinct from, the global Anthropocene). This allows us to evaluate proxy records for human impact on the Icelandic environment and to assess how and when they show transformative impact. Based on this analysis, we consider the implications for understanding and defining the Anthropocene in those areas of the Earth where such a clear independent marker of the onset of significant human impacts is lacking. Postprint

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (10(0) to 10(3) h). However, their impacts are rarely considered in studies of long-term landscape evolution (10(3) y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic (3)He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m(3)/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene.

In order to assess possible contributions of climate change to the human ecology of the North Atlantic islands we evaluate the utility of cumulative deviations from the mean, calculated for the Greenland ice core storm frequency proxy (GISP2 Na+) and sea ice proxy (GISP2 chloride excess). Our aim is to identify episodes of unpredictable change in the context of long-term trends of cultural and environmental development. Key changes are identified in the proxy climate records in 975 and 980 ad, 1025 and 1040 ad, 1180 ad, 1425 and 1450 ad, and 1520 and 1525 ad. Some of these changes are consistent with those inferred from new studies of the palaeoecological record of the Faroes. This indicates that the cumulative deviation measure could give greatest prominence to the most important climate changes affecting landscapes and settlement (such as the changes of 1425 and 1450 ad and their immediate aftermath), rather than extreme events, such as great single storms.

Hubbard, Alun; Sugden, D.; Dugmore, A.; Norddahl, H., (2006) 'A modelling insight into the Icelandic Last Glacial Maximum ice sheet', Quaternary Science Reviews 25(17-18) pp.2283-2296 RAE2008

A chronology of Holocene fluctuations of small outlet glaciers from the Regnabuðajokull ice cap on Hrutfell, central Iceland, allows comparison of their sensitivity with the margin of the nearby Langjokull icefield, to ascertain which frequencies of climatic variability are recorded by adjacent glaciers of different size. Dating utilised tephra layers in aeolian soils lying on, between and beneath moraine ridges. Key marker isochrones dating from the Hekla 4 tephra ( c . 3.8 ka BP) to Katla A.D. 1918 provide unequivocal bracketing ages. The stratigraphy and geochemical fingerprinting of tephras on younger moraines allows subdivision of “Little Ice Age” moraines. Five groups of moraines are identified, at c . 4.5–5.0, c . 3.0–3.5 ka BP, c . 2.0–2.5 ka BP, and from the “Little Ice Age” at c . A.D. 1700 and in the late 19th/early 20th century. These represent a Neoglacial sequence in which steep, small glaciers readvanced to similar positions during what are here termed “Little Ice Age”-type periods (LIATPs). In contrast, the nearby margins of Langjokull show evidence of a late nineteenth-century advance only, suggesting that this was the Holocene maximum for this glacier. The contrasting responses of local glaciers and the large icefield are explained by their different sizes and response times, so that the preserved moraine record is largely pre-conditioned by the glacier type. In general, the forefields of steep, fast-responding glaciers contain more complete archives of Holocene climatic changes than do the margins of the large icefields.

This paper presents geomorphological and sedimentological evidence for three large-scale floods to the west of the ice-capped volcano Katla around the time of Norse settlement or Landnam (AD 870-930). These glacial outburst floods (jokulhlaups), the most recent prehistoric events in a series of Holocene floods in the Markadljot valley, are securely dated by tephrochronology and radiocarbon dating to between c. AD 500 and c. AD 900. The environmental impact of these events would have been extensive, affecting both the highlands and about 40-50 km 2 ofthe coastal lowlands where about 15 of the 400 or so landnam farms in Iceland were sited. An awareness of environmental conditions and landscape stability around the time of the Norse colonisation of Iceland is important to understand the earliest settlement patterns because of the different constraints and opportunities that they represent.

Two megafloods in the canyon of the Jokulsi i Fjóllum, the major northern routeway for glaciovolcanic floods from Vatnajókull, have been closely dated by 14C AMS dates from Betula macrofossils within peat immediately below beds of flood-deposited sand. Ages of c. 4415 and c. 4065 yr BP (5020 and 4610 cal. yr BP) are consistent with the presence of the Hekla 4 tephra (c. 3830 yr BP) resting on the upper surface of the younger flood sand. These sediments are correlated across the Jókulsa a Fjollum canyon with the upper flood sands in a stack recording around 16 flood events. Deposits on both sides of the canyon were trimmed by the last megaflood after the Hekla 3 tephra fall at c. 2900 yr BP, and the highest Holocene flood stages were at the culmination of a series peaking at c. 3500 yr BP. These floods have wider palaeoclimatic significance because they require the formation of large subglacial reservoirs below Vatnajókull. Therefore, the dated floods indicate that a large composite ice cap covered volcanoes in the southeastern highlands through the early and middle Holocene, and that flood routeways largely switched to the south after c. 3500 yr BP.

The marine radiocarbon reservoir effect is an offset in 14C age between contemporaneous organisms from the terrestrial environment and organisms that derive their carbon from the marine environment. Quantification of this effect is of crucial importance for correct calibration of the 14C ages of marine-influenced samples to the calendrical timescale. This is fundamental to the construction of archaeological and palaeoenvironmental chronologies when such samples are employed in 14C analysis. Quantitative measurements of temporal variations in regional marine reservoir ages also have the potential to be used as a measure of process changes within Earth surface systems, due to their link with climatic and oceanic changes. The various approaches to quantification of the marine radiocarbon reservoir effect are assessed, focusing particularly on the North Atlantic Ocean. Currently, the global average marine reservoir age of surface waters, R(t), is c. 400 radiocarbon years; however, regional values deviate from this as a function of climate and oceanic circulation systems. These local deviations from R(t) are expressed as +R values. Hence, polar waters exhibit greater reservoir ages (δR = c. +400 to +800 14C y) than equatorial waters (δR = c. 0 14C y). Observed temporal variations in δR appear to reflect climatic and oceanographic changes. We assess three approaches to quantification of marine reservoir effects using known age samples (from museum collections), tephra isochrones (present onshore/offshore) and paired marine/terrestrial samples (from the same context in, for example, archaeological sites). The strengths and limitations of these approaches are evaluated using examples from the North Atlantic region. It is proposed that, with a suitable protocol, accelerator mass spectrometry (AMS) measurements on paired, short-lived, single entity marine and terrestrial samples from archaeological deposits is the most promising approach to constraining changes over at least the last 5 ky BP.

The arrival of the Vikings in the Faroe Islands and Iceland in the ninth century AD from Scandinavian and British Isles homelands essentially represented the colonisation of virgin landscapes. Environmental investigations show that their imported agricultural package was supplemented in coastal areas by bird and marine resources which, for the Faroes at least, continued to be of significance. The Faroese also developed appropriate land management practices such as outfield grazing and soil augmentation to counteract any detrimental affects arising from, for instance, reductions in the bird population, soil and slope erosion and the lack of naturally fertile soils. It seems that there had always been sufficient resources available for an enterprising human population and that the Faroes did not exceed their carrying capacity during the Norse period. The Icelanders faced different challenges: a more extreme climate, the rapid and substantial erosion of volcanic soils following settlement and the di...

Hovsdalur, an area delimited by the great cirques of upland central Suðuroy, draining into the valley of the Hovsa and terminating in the east at the coastal amphitheatre of Hovsfjo rdur, is a microcosm of the Faroes. The area contains the physical and economic features which characterize the greater part of the island group—mountain, valley, and coast, and marine, cultivation, and grazing environments. Data comprising mainly geomorphological, palynological, and pedological evidence, covering the period prior to and subsequent to the initial Norse settlement (landnam), are used to test a series of hypotheses which exemplify the human ecology of the area. Not all the hypotheses, or aspects of them, proved acceptable—the Norse period clearly coincided with a number of vegetational and pedological changes, but this must be set partly against a backdrop of long-term geomorphological activity.

We present palaeoenvironmental, geomorphological, archaeological, and place-name data which allow a holistic assessment of the history of landscape change on Sandoy, Faroe Islands, especially in terms of the changes that occurred in response to the colonization of the island by humans. In contrast to other situations in the North Atlantic region, there is considerable continuity in the patterns and processes of landscape evolution across the initial settlement horizon. Many of the characteristic features of post-settlement North Atlantic landscapes—absence of trees, widespread blanket mires, high rates of soil erosion—were already in place when the first people arrived. Although human impact on Sandoy appears to have been light, conversely, the unusual environment forced major alterations of the subsistence economy imported by the colonists. Settlement-era archaeological records suggest that, from the start, patterns of resource use differed substantially from the regional norm, and these differences became amplified over time as the Faroese economy created a locally sustainable cultural landscape.

In Iceland, studies that integrate local perceptions about the landscape with scientific evidence of change have been few. This article presents a case study from southeast Iceland that has two main objectives. Firstly, ethnographic data is used to explore the human dimension of the Little Ice Age through perceptions of landscape and climatic change and to describe the impacts that these changes had on life and livelihood. Secondly, the paper critically assesses the coherence of the scientific record regarding the Little Ice Age glacial maximum with evidence gained from the ethnographic survey and the local historical record. Although climatic deterioration from the seventeenth through nineteenth centuries ultimately affected farming viability, it was the interplay of climate with concomitant cultural and socio-economic factors that ensured effective strategies were emplaced to preserve life and livelihood in southeast Iceland. Furthermore, despite different trajectories of perception emanating from either the scientific or the local points of view, data from all sources are strongly coherent and point to a Little Ice Age maximum during the late eighteenth to early nineteenth centuries. This study also illustrates that sensitive landscapes can ‘store memories’ through the cumulative accumulation of disturbances during periods of climatic variability, eventually reaching a critical threshold and inducing landscape instability, such as occurred during the nineteenth century.

Radiocarbon ages were measured on replicate samples of burnt grain and 5 mollusk species collected from a single sealed layer at an archaeological site (Hornish Point) on the west coast of South Uist, Scotland. The aim was to examine the impact of using different mollusk species on ΔR determinations that are calculated using the paired terrestrial/marine sample approach. The mollusk species examined inhabit a range of environments and utilize a variety of food sources within the intertidal zone. Several authors have suggested that these factors may be responsible for observed variations in the 14C activity of mollusk shells that were contemporaneous in a single location. This study found no significant variation in the 14C ages of the mollusk species, and consequently, no significant variation in calculated values of ΔR. The implication is that in an area where there are no carboniferous rocks or significant local inputs of freshwater to the surface ocean, any of a range of marine mollusk species can be used in combination with short-lived terrestrial material from the same secure archaeological context to accurately determine a ΔR value for a particular geographic location and period in time.

Evidence is provided from the joint application of tephrochronology and palynology in two Icelandic locations — the island of Papey off the east coast and Seljaland in the south. The Papey study relates to vegetation change around the time of volcanic ash deposition from the eruption of Katla in 1755. This produced various hypotheses concerning volcanic impacts and land-use activities, including changes in nutrient inputs, grazing activity, and climate. Similar data have been obtained from Seljaland, where a group of farms was affected by fall-out from the 1947 eruption of Hekla. The patterns of pollen-based vegetational change were similar at both locations, enabling a fuller exploration of floristic and anthropogenic responses to ash deposition. The Seljaland data are influenced by the known removal of livestock in order to guard against the effects of fluorosis. The resultant cessation of grazing was probably responsible for much of the vegetational change apparent in the pollen record, and this represents a credible recent analogue for processes that may have taken place in Papey in 1755.

A three-dimensional, time-dependent numerical ice-sheet model is used to investigate the southern extent of the last Icelandic ice-sheet since the Last Glacial Maximum (LGM, ca. 20 000 14C yr BP). Ice development over southern Iceland is forced using a linear relationship between mass balance and altitude based on observations over Solheimajokull, a southern outlet glacier of the Mýrdalsjokull ice-cap. A continentality factor is introduced that raises inland equilibrium-line altitudes (ELAs) and also slackens the mass-balance/altitude gradient driving the model. With this calibration the present-day ice distribution can be reconstructed. Growth from ice-free to total ice cover is assessed and the sensitivity of ice extent to ELA change is shown to be non-linear. The model indicates that an ELA lowering of 500 m, consistent with a ca. 5°C temperature depression for southern Iceland at the LGM, would enable glacier ice to cover the whole land surface within the modelled area and inundate any putative ecological refugia. Modelling with a 300 m ELA depression, consistent with previous reconstructions of Younger Dryas (YD, 10 000–11 000 14C yr BP) ice extent, indicates that the principal outcrops of the Solheimar ignimbrite were glaciated at this time, suggesting that an origin during this stadial (and a correlation with North Atlantic Ash Zone I / Vedde Ash) is problematic. Copyright © 2003 John Wiley & Sons, Ltd.

Glacier responses to tephra deposition are shown to be highly variable where wind-transported eruption plumes produce narrow distal fallout zones with steep lateral thickness gradients. Significant but short-lived advances of faster-flowing glaciers can be triggered by deposition from modest eruptions. The 1947 eruption of Hekla, south Iceland, covered nearby glaciers with variable thicknesses of tephra, causing dramatic spatial variations in ablation rate. Relative snow ablation increased by an estimated >80% at the eastern margin of Eyjafjallajökull, but decreased by >54% at the western margin. Relative ice ablation increased by only 4% in the east but decreased by >75% at the western margin, only 15 km distant. The effect on mass balance therefore depends on tephra distribution as well as on the nature of the glacier surface. On Gígjökull, retardation of ablationwas greatest at the terminus, associated with an anomalous advance of ≥328 m between 1947 and 1954. Other glaciers in the fallout zone show either no recognizable response, or accelerated retreat. Advances will be short-lived due to the rapid redistribution of supraglacial tephra in a maritime climate, and the potential for discriminating between volcanically and climatically forced advances in the glacio-geomorphological record is low. The long-term glaciological effect of volcanism is to create thin, low-albedo covers after reworking, which make conditions less favourable for glaciation.

We use a coupled energy-balance/glacier-flow model to reconstruct Holocene climate from a 5000-yr record of glacier length fluctuations at Solheimajokull, an outlet glacier in southern Iceland. The climatic reconstruction is presented in terms of Equilibrium-Line Altitude and is translated to envelopes of possible temperature and precipitation changes. The reconstruction is highly resolved between AD 1700 and 1990: the 20th Century retreat of the glacier resulted from a warming between AD 1920 and 1940 while the advance since AD 1970 was in response to both a cooling and a precipitation increase after AD 1940. The early 18th Century climate of Iceland was warm, comparable to that of the early 20th Century, while the coldest period in recent history occurred during the 1780s. Earlier Holocene glacier advances at about 5000, 3100 and 1400 yr BP, and in the 10th and 14th Centuries AD resulted from cooling of 1–2°C, and correlate with worldwide glacier expansion, atmospheric changes in Greenland and changes in ocean circulation north of Iceland. Glacier expansions follow periods when sea ice is extensive in the Greenland and Barents Sea. Resulting temperature changes mean that natural climatic variability has a large signature in Iceland, making it difficult to isolate any longer term trends, such as an enhanced anthropogenic signal.

This work is supported by a UK Natural Environment Research Council (NERC) PhD studentship (NE/F00799X/1) The chronological challenge of cross-scale analysis within coupled socio-ecological systems can be met with tephrochronology based on numerous well-dated tephra layers. We illustrate this with an enhanced chronology from Skaftártunga, south Iceland that is based on 200 stratigraphic profiles and 2635 individual tephra deposits from 23 different eruptions within the last 1140 years. We present new sediment-accumulation rate based dating of tephra layers from Grímsvötn in AD 1432 ± 5 and AD 1457 ± 5. These and other tephras underpin an analysis of land surface stability across multiple scales. The aggregate regional sediment accumulation records suggest a relatively slow rate of land surface change which can be explained by climate and land use change over the period of human occupation of the island (after AD ∼870), but the spatial patterning of change shows that it is more complex, with landscape scale hysteresis and path dependency making the relationship between climate and land surface instability contingent. An alternative steady state of much higher rates of sediment accumulation is seen in areas below 300 m asl after AD ∼870 despite large variations in climate, with two phases of increased erosion, one related to vegetation change (AD 870–1206) and another related to climate (AD 1597–1918). In areas above 300 m asl there is a short lived increase in erosion and related deposition after settlement (AD ∼870–935) and then relatively little additional change to present. Spatial correlation between rates of sediment accumulation at different profiles decreases rapidly after AD ∼935 from ∼4 km to less than 250 m as the landscape becomes more heterogeneous. These new insights are only possible using high-resolution tephrochronology applied spatially across a landscape, an approach that can be applied to the large areas of the Earth's surface affected by the repeated fallout of cm-scale tephra layers. Postprint

At least 12 silicic tephra layers (SILK tephras) erupted between ca. 6600 and ca. 1675 yr BP from the Katla volcanic system, have been identified in southern Iceland. In addition to providing significant new knowledge on the Holocene volcanism of the Katla system which typically produces basaltic tephra, the SILK tephras form distinct and precise isochronous marker horizons in a climatically sensitive location close to both the atmospheric and marine polar fronts. With one exception the SILK tephras have a narrow compositional range, with SiO2 between 63 and 67%. Geochemically they are indistinguishable from ocean transported pumice found on beaches in the North Atlantic region, although they differ significantly from the silicic component of the North Atlantic Ash Zone One (NAAZO). Volumes of airborne SILK tephra range from 0.05 to 0.3 km3. We present new isopach maps of the six largest layers and demonstrate that they originate within the Katla caldera. The apparently stable magma system conditions that produced the SILK tephras may have been established as a consequence of the eruption of the silicic component of NAAZO (ca. 10.3 ka) and disrupted by another large-scale event, the tenth century ad Eldgja eruption (ca. 1 ka). Despite the current long repose, silicic activity of this type may occur again in the future, presenting hitherto unknown hazards. Copyright © 2001 John Wiley & Sons, Ltd.

Tephrochronology is used to date mid-Holocene moraines in Iceland. In the Granavatn cirque (Trollaskagi Peninsula) the H-4 tephra (ca. 3830 yr BP) lies within sediment accumulated against the distal slope of a lateral moraine, providing a minimum age for glaciation, and the absence of H-5 (ca. 5950 yr BP) provides a maximum age. By implication, the cirque was glaciated in the early Neoglacial period. A large rock glacier, the development of which post-dates the moraine, probably formed within the ‘Little Ice Age’ (LIA) of the sixteenth to nineteenth centuries ad. At Eystri-Loðmundarjokull in central Iceland, frozen colluvium containing the H-3 (ca. 2900 yr BP) and H-4 tephras provides a minimum age of ca. 3830 yr BP for two terminal moraines, and a maximum age of ca. 2900 yr BP for a third. The older moraines are correlated with the Vatnsdalur I/Drangagil advances (ca. 4700 yr BP and ≥ 4500 yr BP respectively) and the Begisardalur I advance (ca. 4200 yr BP). They imply that early Neoglacial advances throughout Iceland were locally more extensive than those of the LIA. The apparent LIA Holocene glacial maximum may reflect (i) selective sampling of large ice-cap-outlet glaciers, where the preservation potential of pre-LIA deposits is low, and (ii) reliance on lichenometric dating, which has a restriced temporal range. Copyright © 2001 John Wiley & Sons, Ltd.

In discussions of landscape sensitivity, human activities have generally been regarded as external forces contributing to landscape change, with a focus on the impacts of cultivation methods, fertiliser practices, grazing pressures and atmospheric pollution. However, there has been comparatively little study undertaken that integrates physical and social systems in a historic context to explain the basis of human activity in sensitive landscapes. Where such attempts have been made, the manner of common land management has figured prominently, with ‘tragedy of the commons’ concepts used to explain land degradation and to provide a foundation for policy response. This has also been the case in Southern Iceland and in this paper we assess the extent to which common land domestic grazing pressures were the primary external force causing soil erosion and land degradation during the period of occupation from ca. 874 AD. We first provide field observation of soil erosion, temporally defined by tephrochronology, to highlight the extent of land degradation during this period. The ‘tragedy of the commons’ explanation of degradation is then assessed by evaluating historic documentary sources, and by environmental reconstruction and modeling of historic grazing pressures. These analyses indicate that regulatory mechanisms were in place to prevent overgrazing from at least the 1200s AD and suggest that there was sufficient biomass to support the numbers of domestic livestock indicated from historic sources. We suggest that failure to remove domestic livestock before the end of the growing season and an absence of shepherding were more likely to contribute to land degradation than absolute numbers. Lack of appropriate regulation of domestic livestock on common grazing areas can be attributed to limited cultural knowledge of changing and rapidly fluctuating environmental conditions.

The first human impacts on the Icelandic environment came with the Norse colonisation or Landnam of the ninth century AD. The colonisation represents a fundamental environmental change that is both rapid and profound. In this paper we assess geomorphological dimensions of the initial settlement period using a tephrochronology that includes the Landnam Tephra, erupted ca. 870 AD, two tenth century AD tephras KR 920 and E 935, and 11 other well dated tephra layers. We report a new 14C age of 1676 ±12 14C yr BP (cal AD 345 (400) 419) for the tephra SILK-YN which forms a key prehistoric marker horizon that constrains rates of environmental change in the centuries before Norse Settlement. Aeolian sediment accumulation rates show five geomorphological responses to settlement that differ in the rate and trajectory of change. These distinct anthropogenic signals are the result of spatially variable sensitivity to grazing and deforestation, and reflect the extent of local soil erosion. This critical erosio...

The number of tiger subspecies is a major conservation issue that is difficult to resolve owing to small fragmented extant populations and limited historical samples in museums, which compromise the rigour of both molecular and morphological taxonomic studies. Rather than considering a static taxonomic approach to geographical variation in the tiger, we consider the changing biogeographical range of the tiger through the last glacial-interglacial cycle, based on habitat associations of modern tiger specimen records, and environmental reconstructions from the Last Glacial Maximum (LGM; approximately 20000 years before present (B.P.)). We regard this cycle as representative of the numerous glacial cycles that span the evolutionary history of the tiger since its appearance in the fossil record about two million years ago, thereby giving a deep-time perspective. The key issue is to determine the extent to which ancestral populations of the tiger were geographically isolated. If no geographical isolation is likely, and gene flow between tiger populations could be maintained until modern times, then diagnosably distinct populations could not have evolved. Our reconstructions show that only two tiger populations were likely to have experienced significant geographical isolation from the main species distribution; these were to the west of Tibet (during the LGM) and on Japan (throughout the glacial cycle). In addition, the LGM is likely to have seen the partial separation of peninsular Malayan and Sunda Islands tigers from mainland populations. From a biogeographical perspective it seems probable that only three contemporary populations were sufficiently separated for the evolution of distinct populations, which can be regarded as subspecies or evolutionary significant units. Therefore, most variation in modern tiger populations is probably clinal, which has important implications for future conservation strategies both in the wild and in captivity.

The major element chemistry of nine silicic tephras of historical age from Iceland is assessed as a key step in the development of the recent tephrochronology of the North Atlantic region. The tephras include the largest such layers produced by each of the five central volcanoes Hekla, Ö ræfajökull, Eyjafjallajökull, Torfajökull and Askja since the ninth century ad (H 1104, Ö1362, E 1821, Landnám tephra c. 870, A 1875) and four other tephras (H 1158, H 1510, H 1947, Ö1727). The determination of grain discrete major element chemistry of the glass fraction is a fundamental stage in the identification and correlation of tephra, and allows links to be made between Icelandic source areas (with precise dating evidence) and distal deposits elsewhere in the North Atlantic region. Although major element data can be used to discriminate between tephra layers produced by the different central volcanoes, on its own it cannot be used to identify all the Holocene layers produced by each central volcano. However, integration with other stratigraphic and chronological data can resolve ambiguous cases, permitting the confident identification of precise isochrones.

The loss of the Norse Western Settlement in Greenland around the mid-fourteenth century has long been taken as a prime example of the impact of changing climate on human populations. This study employs an interdisciplinary approach combining historical documents, detailed archaeological investigations, and a high-resolution proxy climate record from the Greenland Ice Sheet Project 2 (GISP2) to investigate possible causes for the end of this settlement. Historical climate records, mainly from Iceland, contain evidence for lowered temperatures and severe weather in the north Atlantic region around the mid-fourteenth century. Archaeological, palaeoecological and historical data specifically concerning the Western Settlement suggest that Norse living conditions left little buffer for unseasonable climate, and provide evidence for a sudden and catastrophic end around the mid-fourteenth century. Isotopic data from the GISP2 ice core provide annual- and seasonal-scale proxy-temperature signals which suggest multiyear intervals of lowered temperatures in the early and mid-fourteenth century. The research synthesized here suggests that, while periods of unfavourable climatic fluctuations are likely to have played a role in the end of the Western Settlement, it was their cultural vulnerabilities to environmental change that left the Norse far more subject to disaster than their Inuit neigh bours.

A first rule of statistics is that the existence of a correlation does not itself prove a causal connection. This is the heart of the recurrent question in later European prehistory — whether in the Mediterranean or in the Atlantic northwest — about volcanic eruptions, their impact on climate, and then of the climatic impact on human populations. The burial under tephra of the Late Bronze Age settlement of Santorini is proof of a particular catastrophe: but is there the evidence to prove wider European calamity?

The object of the study was to assess the effects of a range of pretreatment/extraction schemes on the yields of humic acid and humin obtained from peat and the subsequent radiocarbon ages. We analyzed peat from Flókadalur in northern Iceland, collecting material from a profile containing seven visible tephra horizons in the upper 3 m, whose form and extent indicated little disturbance to the section over the last 4000 yr. The results of a range of pretreatments demonstrated that time rather than the strength of alkali is the more important factor governing the extraction of humic acid. An increase in alkali molarity did not correspond to any systematic increase in yield, whereas an increase in time did, implying that the extraction is kinetically controlled. We found no evidence of variability in 14C age due to pretreatment scheme or between different geochemical fractions of the peat. Further implications from this study are that bog stability and ecological simplicity produce a favorable environment for 14C dating.

Between ca. A.D. 800–1000, Scandinavian chiefly societies with a mixed maritime and agricultural economy expanded into the North Atlantic, colonizing Shetland, Orkney, Caithness, Hebrides, Faeroes, Iceland, Greenland, and Vinland. The settlers brought continental European economics and expectations to a widely varied set of island ecosystems. In many regions, rapid degradation of flora and soils took place associated with social and climate change. Recent research coordinated by the North Atlantic Bicultural Organization (NABO) highlights the extent of pre-modern impacts.

We report on the earliest archaeological evidence from the Faroe Islands, placing human colonization in the 4th–6th centuries AD, at least 300–500 years earlier than previously demonstrated archaeologically. The evidence consists of an extensive wind-blown sand deposit containing patches of burnt peat ash of anthropogenic origin. Samples of carbonised barley grains from two of these ash patches produced 14C dates of two pre-Viking phases within the 4th–6th and late 6th–8th centuries AD. A re-evaluation is required of the nature, scale and timing of the human colonization of the Faroes and the wider North Atlantic region.

Greenland, far north land of the Atlantic, has often been beyond the limit of European farming settlement. One of its Norse settlements, colonized just before AD 1000, is — astonishingly — not even at the southern tip, but a way up the west coast, the ‘Western Settlement’. Environmental studies show why its occupation came to an end within five centuries, leaving Greenland once more a place of Arctic-adapted hunters.

This paper reports the presence and geochemical characteristics of seven separate tephras in Scotland that fell in AD 1510, and about 450 BP, 2100 BP, 3600 BP, 3830 BP, 5600 BP and around 6000 BP. The results come from 14 peat bogs spread throughout the Highlands and Islands where 26 tephra deposits have been characterized using over 400 grain-discrete electron-probe micro-analysis. Firstly, tephras are identified and defined by major element characteristics at a reference site. Secondly, tephras are linked between sites on the basis of geochemistry, and dated. Informal names, based on British sites, are suggested for tephras not yet linked to precise sources in Iceland. Despite some apparent variation in colour, all analysed grains in these seven deposits are silicic or intermediate in composition (SiO2>57%). This phenomenon does not appear to be an artifact of preservation for two reasons. First, small (