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Analyzing the spatial and temporal properties of information flow with a multi-century perspective could illuminate the sustainability of human resource-use strategies. This paper uses historical and archaeological datasets to assess how spatial, temporal, cognitive, and cultural limitations impact the generation and flow of information about ecosystems within past societies, and thus lead to tradeoffs in sustainable practices. While it is well understood that conflicting priorities can inhibit successful outcomes, case studies from Eastern Polynesia, the North Atlantic, and the American Southwest suggest that imperfect information can also be a major impediment to sustainability. We formally develop a conceptual model of Environmental Information Flow and Perception (EnIFPe) to examine the scale of information flow to a society and the quality of the information needed to promote sustainable coupled natural-human systems. In our case studies, we assess key aspects of information flow by focusing on food web relationships and nutrient flows in socio-ecological systems, as well as the life cycles, population dynamics, and seasonal rhythms of organisms, the patterns and timing of species’ migration, and the trajectories of human-induced environmental change. We argue that the spatial and temporal dimensions of human environments shape society's ability to wield information, while acknowledging that varied cultural factors also focus a society's ability to act on such information. Our analyses demonstrate the analytical importance of completed experiments from the past, and their utility for contemporary debates concerning managing imperfect information and addressing conflicting priorities in modern environmental management and resource use.

Glacial outburst floods (jökulhlaups) have been a significant driver of landscape evolution, environmental change, and geohazards throughout the Quaternary. Iceland experiences more frequent jökulhlaups than nearly anywhere else on Earth, though most research focuses on subglacial volcanogenic floods that drain across outwash plains. Abundant geomorphologic evidence exists for largescale jökulhlaups that drained along the modern-day course of the Hvítá River in southwestern Iceland during early Holocene deglaciation, originating from ice-dammed Glacial Lake Kjölur; yet only one previous publication has investigated these events. This study uses a combination of field mapping and remote sensing to identify new jökulhlaup geomorphologic evidence along the Hvítá River, including erosional landforms such as scoured bedrock, anastomosing channel networks, cataracts, and canyons, and depositional features such as boulder bars and channel infill. We synthesize new findings with previously reported work to: 1) present an updated geomorphologic map of Hvítá jökulhlaup evidence; 2) reconstruct flood drainage routes, landscape impact, hydrology, and relative chronology; and 3) hypothesize scenarios of ice margin position and glacial lake evolution. Interpreting flood landform assemblages reveals a more extensive geomorphologic record than previously reported, with a complex drainage pattern along four separate routes from two potentially different sources. Reconstructed peak flow discharges span four orders of magnitude from 10² to 10$^5$ m³/s. Geomorphologic and paleohydraulic results introduce four hypothesized drainage scenarios, though absolute geochronology is necessary to determine whether multiple floods drained along each route. The Hvítá jökulhlaups yield insight into the timing and dynamics of the final phase of Icelandic Ice Sheet decay, advancing understanding of Iceland’s Pleistocene–Holocene transition, demonstrating the importance of high magnitude, low frequency floods in landscape evolution, and serving as an analogue to ice and meltwater response to past, present, and future climate warming in glaciated regions worldwide.

Financial support for this work was provided by NERC Doctoral Training Partnership Ph.D. studentship NE/L002558/1 to Polly I. J. Thompson. We explore the effect small-scale surface features have on influencing the morphology and grain-size distribution (GSD) of tephra layers within the Quaternary stratigraphy of sub-polar landscapes. Icelandic thúfur, small cryogenic earth mounds, are used to assess how and why the morphology and GSD of tephra layers vary over such formations. Through measurement of tephra layer thickness and GSD, Hekla 1947 and Grímsvötn 2011 tephra layers are analysed. Results indicate that such microtopographic features do indeed alter the form of tephra deposits and therefore the tephra layer that is preserved in the stratigraphy. Tephra thickness is significantly greater in hollows than on the thúfur crests. There is greater variation in tephra thickness measurements from thúfur in comparison to control measurements from a surface where thúfur are absent. Thúfur crests contain larger grain sizes than hollows, for both H1947 and G2011 tephras; however this was only statistically significant for the G2011 tephra. Such morphological patterns are thought to arise from an interplay of tephra characteristics, altered topography from the thúfur formations and earth surface processes operating at the sites. This study provides insight into the potential of tephra layer morphology and internal structures as indicators of Quaternary landforms and processes. Additionally, it provides important context for the appropriate sampling of tephra layers to infer volcanological processes, as the characteristics of preserved layers do not necessarily reflect those of the original fall-out. Publisher PDF

Funding: This work was supported by the NERC Doctoral Training Partnership Ph.D. studentship: NE/ L002558/1 to PT. We explore whether the rate at which a tephra deposit is buried influences the variability (thickness and grain size distribution) within the tephra layer subsequently preserved within the stratigraphic record. This has important implications for understanding how processes of soil formation interact with the creation of a volcanic record. To assess the relationship between soil formation and the preservation of tephra layers, the thickness and grain size distribution of the Katla 1918 tephra in Iceland and the rate at which it was buried (inferred from the thickness of the overlying soil) was measured 1620 times at six locations. Tephra layer thickness does not correlate with rate of burial, but the proportion of original deposit retained does, and variations in grain size distribution are correlated with burial rate. Our results indicate that whilst medium term (i.e. years-decades) burial processes may contribute less to tephra layer variability than environmental processes operating immediately after deposition, rapid burial facilitates better preservation of the original fallout characteristics with important implications for the accurate reconstruction of past volcanic eruptions based on tephra layer characteristics. There are two key implications: firstly, sites need to be chosen where surface characteristics minimise the initial alterations of tephra deposits, and secondly sites with rapid burial will produce the best quality data, although workable data can be gathered elsewhere if areas of uncertainty are acknowledged. Publisher PDF

The authors would also like to acknowledge the support of the National Science Foundation, specifically the Arctic Social Sciences Program, and RANNIS (The Icelandic Center for Research). Archaeological records provide a unique source of direct data on long-term human-environment interactions and samples of ecosystems affected by differing degrees of human impact. Distributed long-term datasets from archaeological sites provide a significant contribution to establish local, regional, and continental-scale environmental baselines and can be used to understand the implications of human decision-making and its impacts on the environment and the resources it provides for human use. Deeper temporal environmental baselines are essential for resource and environmental managers to restore biodiversity and build resilience in depleted ecosystems. Human actions are likely to have impacts that reorganize ecosystem structures by reducing diversity through processes such as niche construction. This makes data from archaeological sites key assets for the management of contemporary and future climate change scenarios because they combine information about human behavior, environmental baselines, and biological systems. Sites of this kind collectively form Distributed Long-term Observing Networks of the Past (DONOP), allowing human behavior and environmental impacts to be assessed over space and time. Behavioral perspectives are gained from direct evidence of human actions in response to environmental opportunities and change. Baseline perspectives are gained from data on species, landforms, and ecology over timescales that long predate our typically recent datasets that only record systems already disturbed by people. And biological perspectives can provide essential data for modern managers wanting to understand and utilize past diversity (i.e., trophic and/or genetic) as a way of revealing, and potentially correcting, weaknesses in our contemporary wild and domestic animal populations. Postprint

The North Atlantic Biocultural Organization (NABO) community initiated dataARC to develop digital research infrastructures to support their work on long-term human-ecodynamics in the North Atlantic. These infrastructures were designed to address the challenges of sharing research data, the connections between those data and high-level interpretations, and the interpretations themselves. In parallel, they were also designed to support the reuse of diverse data that underpin transdisciplinary synthesis research and to contextualise materials disseminated widely to the public more firmly in their evidence base. This article outlines the research infrastructure produced by the project and reflects on its design and development. We outline the core motivations for dataARC's work and introduce the tools, platforms and (meta)data products developed. We then undertake a critical review of the project's workflow. This review focuses on our understanding of the needs of stakeholder groups, the principles that guided the design of the infrastructure, and the extent to which these principles are successfully promoted in the current implementation. Drawing on this assessment, we consider how the infrastructure, in whole or in part, might be reused by other transdisciplinary research communities. Finally, we highlight key socio-technical gaps that may emerge as structural barriers to transdisciplinary, engaged, and open research if left unaddressed.

We present major new findings on the stability of Norse landing places on the island of Unst, Shetland using a combination of geomorphology, OSL dating, fetch analysis and sediment transport modelling. Islanders needed reliable access to the sea, and exploited sandy beaches as safe landing places. The persistence of beaches was important for long-term continuity of settlement and could be threatened by stormy conditions. Sediment modelling undertaken on two embayments on Unst, Lunda Wick and Sandwick, reveals major differences in the ability of sandy beaches to reform in these embayments after the onset of persistent stormy conditions; sandy beaches can endure under these conditions at Sandwick, but not at Lunda Wick. OSL dating of blown sands at Lunda Wick reveals a history of sand blow events pointing to large scale depletion of beach material throughout the Little Ice Age (beginning circa 1250 CE). This correlates with known sand blows at Sandwick, but here the beach could be replenished from the nearshore environment, something that was more problematic at Lunda Wick. These findings agree with the emerging picture of increased environment pressure from blown sands on communities throughout the North Atlantic and identifies different models of related beach persistence and change.

Financial support was provided by 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’ (both to AJD). Volcanologists frequently use grain size distributions (GSDs) in tephra layers to infer eruption parameters. However, for long-past eruptions, the accuracy of the reconstruction depends upon the correspondence between the initial tephra deposit and preserved tephra layer on which inferences are based. We ask: how closely does the GSD of a decades-old tephra layer resemble the deposit from which it originated? We addressed this question with a study of the tephra layer produced by the eruption of Mount St Helens, USA, in May 1980. We compared grain size distributions from the fresh, undisturbed tephra with grain size measurements from the surviving tephra layer. We found that the overall grain size characteristics of the tephra layer were similar to the original deposit, and that distinctive features identified by earlier authors had been preserved. However, detailed analysis of our samples showed qualitative differences, specifically a loss of fine material (which we attributed to ‘winnowing’). Understanding how tephra deposits are transformed over time is critical to efforts to reconstruct past eruptions, but inherently difficult to study. We propose long-term, tephra application experiments as a potential way forward. Publisher PDF

Aim We use ecological niche models and environmental stratification of palaeoclimate to reconstruct the changing range of the lion (Panthera leo) during the late Pleistocene and Holocene. Location The modern (early 21st century) range of the lion extends from southern Africa to the western Indian Subcontinent, yet through the 20th century this range has been drastically reduced in extent and become increasingly fragmented as a result of human impacts. Methods We use Global Environmental Stratification with MaxEnt ecological niche models to map environmental suitability of the lion under current and palaeoclimatic scenarios. By examining modelled lion range in terms of categorical environmental strata, we characterise suitable bioclimatic conditions for the lion in a descriptive manner. Results We find that lion habitat suitability has reduced throughout the Holocene, controlled by pluvial/interpluvial cycles. The aridification of the Sahara 6ka dramatically reduced lion range throughout North Africa. The association of Saharan aridification with the development of pastoralism and the growth of sedentary communities, who practised animal husbandry, would have placed additional and lasting anthropogenic pressures on the lion. Main Conclusions This research highlights the need to integrate the full effects of the fluctuating vegetation and desiccation of the Sahara into palaeoclimatic models, and provides a starting point for further continental-scale analyses of shifting faunal ranges through North Africa and the Near East during the Holocene. This scale of ecological niche modelling does not explain the current pattern of genetic variation in the lion, and we conclude that narrow but substantial physical barriers, such as rivers, have likely played a major role in population vicariance throughout the Late Pleistocene.

Aim We use ecological niche models and environmental stratification of palaeoclimate to reconstruct the changing range of the lion (Panthera leo) during the late Pleistocene and Holocene. Location The modern (early 21st century) range of the lion extends from southern Africa to the western Indian Subcontinent, yet through the 20th century this range has been drastically reduced in extent and become increasingly fragmented as a result of human impacts. Methods We use Global Environmental Stratification with MaxEnt ecological niche models to map environmental suitability of the lion under current and palaeoclimatic scenarios. By examining modelled lion range in terms of categorical environmental strata, we characterise suitable bioclimatic conditions for the lion in a descriptive manner. Results We find that lion habitat suitability has reduced throughout the Holocene, controlled by pluvial/interpluvial cycles. The aridification of the Sahara 6ka dramatically reduced lion range throughout North Africa. The association of Saharan aridification with the development of pastoralism and the growth of sedentary communities, who practised animal husbandry, would have placed additional and lasting anthropogenic pressures on the lion. Main Conclusions This research highlights the need to integrate the full effects of the fluctuating vegetation and desiccation of the Sahara into palaeoclimatic models, and provides a starting point for further continental-scale analyses of shifting faunal ranges through North Africa and the Near East during the Holocene. This scale of ecological niche modelling does not explain the current pattern of genetic variation in the lion, and we conclude that narrow but substantial physical barriers, such as rivers, have likely played a major role in population vicariance throughout the Late Pleistocene.

This research was supported by grants from the Royal Geographical Society (ref: SRG 01/18) and Quaternary Research Association to NAC. Tephra layers are frequently used to reconstruct past volcanic activity. Inferences made from tephra layers rely on the assumption that the preserved tephra layer is representative of the initial deposit. However, a great deal can happen to tephra after it is deposited; thus, tephra layer taphonomy is a crucial but poorly understood process. The overall goal of this research was to gain greater insight into the taphonomy of terrestrial tephra layers, specifically the extent to which deposit thickness is altered over time, with implications for tephra volume estimation. We approached this by a)conducting a new survey of the tephra layer from the recent, well-studied eruption of Mount St Helens on May 18th, 1980 (MSH1980); b)modelling the tephra layer thickness using a mathematical technique and c)comparing our results with an equivalent model based on measurements taken immediately after the eruption. In this way, we aimed to quantify any losses and transformations that have occurred. During our study, we collected measurements of tephra layer thickness from 86 locations ranging from 600 km from the vent. Geochemical analysis was used to identify tephra of uncertain origin. Our results indicated that the extant tephra layer at undisturbed sites was representative of the original deposit: overall, preservation in these locations (in terms of thickness, stratigraphy and geochemistry) had been remarkably good. However, the isopach maps generated from our measurements diverged from isopachs produced in the same way, but derived from the original survey data. Furthermore, our estimates of the quantity of tephra produced during the eruption greatly exceeded previous estimates of the fallout volume. In our study, inaccuracies in the modelled fallout arose from issues of sampling strategy, rather than taphonomy. Our results demonstrate the sensitivity of volcanological reconstructions to measurement location, and the great importance of reliably measured low/zero values in reconstructing tephra deposits. Postprint

Glacial lake outburst floods (GLOFs) have occurred across the planet throughout the Quaternary and are a significant geohazard in Arctic and alpine regions today. Iceland experiences more frequent GLOFs—known in Icelandic as jökulhlaups—than nearly anywhere on Earth, yet most research focuses on floods triggered by subglacial volcanic and geothermal activity. However, floods from proglacial lakes may be a better analogue to most global GLOFs.As the Icelandic Ice Sheet retreated across Iceland in the Late Pleistocene-Early Holocene, meltwater pooled at ice margins and periodically drained in jökulhlaups. Some of the most catastrophic floods drained from ice-dammed Glacial Lake Kjölur, surging across southwestern Iceland from the interior highlands to the Atlantic Ocean. These floods left extensive geomorphologic evidence along the modern-day course of the Hvítá River, including canyons, scoured bedrock, boulder deposits, and Gullfoss—Iceland’s most famous waterfall. The largest events reached an estimated maximum peak discharge of 300,000 m3 s-1, ranking them among the largest known floods in Iceland and on Earth.Yet, all our evidence for the Kjölur jökulhlaups comes from only one publication to date (Tómasson, 1993). My research employs new methods to better constrain flood timing, routing, magnitude, and recurrence interval at this underexplored site. This talk presents new and synthesized jökulhlaup geomorphologic evidence; HEC-RAS hydraulic modeling results of flow magnitude and routing; and ongoing geochronological analyses using cosmogenic nuclide exposure dating and tephrochronology. It also situates these events within Icelandic Ice Sheet deglaciation chronology and environmental change at the Pleistocene-Holocene transition. Finally, it examines the Kjölur floods as an analogue to contemporary ice sheet response, proglacial lake formation, and jökulhlaup processes and landscape evolution in Arctic and alpine regions worldwide, where GLOFs pose an increasing risk to downstream communities due to climate-driven meltwater lake expansion. Citation: Tómasson, H., 1993. Jökulstífluð vötn á Kili og hamfarahlaup í Hvítá í Árnessýslu. Náttúrufræðingurinn 62, 77-98.

Archaeological chronologies use many radiocarbon (14C) dates, some of which may be misleading. Strict ‘chronometric hygiene protocols’, which aim to enhance the overall accuracy and precision of 14C datasets by removing all potentially problematic samples, mean that so few dates remain in some locations that accurate chronologies cannot be established. 14C dates on charcoal can be affected by an ‘old-wood’ effect, and so they are often removed from analyses, despite >40,000 being available worldwide, representing > $25 million. We show that when a Bayesian chronological model is used, which incorporates an Outlier Model specific to wood charcoal, the 14C dataset of Iceland's Viking Age settlement agrees well with ice core-dated tephrochronology and written sources. Greatest accuracy comes from an even temporal distribution of 14C dates and more dates lead to greater precision (

High energy, rocky coastlines often feature sandy beaches within headland‐bound embayments. Not all such embayments have beaches however, and beaches in embayments can be removed by storms and may subsequently reform. What dictates the presence or absence of an embayed beach and its resilience to storms? In this paper, we explore the effect of offshore slope and wind conditions on nearshore sediment transport within idealised embayments to give insight into nearshore sediment supplies. We use numerical simulations to show that sand can accumulate near shore if the offshore slope is >0.025 m/m, but only under persistent calm conditions. Our modelling also suggests that if sediment in an embayment with an offshore gradient steeper than 0.025 m/m is removed during a period of persistent stormy conditions, it will be unlikely to return in sub‐decadal timescales. In contrast, sediment located in embayments with shallower gradients can reform swiftly in both calm and stormy conditions. Our findings have wide implications for contemporary coastal engineering in the face of future global climate change, but also for Quaternary environmental reconstruction. Our simple method to predict beach stability based on slope can be used to interpret differing responses of embayments to periods of changing coastal storminess such as the medieval climate anomaly‐little ice age (MCA‐LIA) transition.

This paper contributes to recent studies exploring the longue duree of human impacts on island landscapes, the impacts of climate and other environmental changes on human communities, and the interaction of human societies and their environments at different spatial and temporal scales. In particular, the paper addresses Iceland during the medieval period (with a secondary, comparative focus on Norse Greenland) and discusses episodes where environmental and climatic changes have appeared to cross key thresholds for agricultural productivity. The paper draws upon international, interdisciplinary research in the North Atlantic region led by the North Atlantic Biocultural Organization (NABO) and the Nordic Network for Interdisciplinary Environmental Studies (NIES) in the Circumpolar Networks program of the Integrated History and Future of People on Earth (IHOPE). By interlinking analyses of historically grounded literature with archaeological studies and environmental science, valuable new perspectives can emerge on how these past societies may have understood and coped with such impacts. As climate and other environmental changes do not operate in isolation, vulnerabilities created by socioeconomic factors also beg consideration. The paper illustrates the benefits of an integrated environmental-studies approach that draws on data, methodologies and analytical tools of environmental humanities, social sciences, and geosciences to better understand long-term human ecodynamics and changing human-landscape-environment interactions through time. One key goal is to apply previously unused data and concerted expertise to illuminate human responses to past changes; a secondary aim is to consider how lessons derived from these cases may be applicable to environmental threats and socioecological risks in the future, especially as understood in light of the New Human Condition, the concept transposed from Hannah Arendt's influential framing of the human condition that is foregrounded in the present special issue. This conception admits human agency's role in altering the conditions for life on earth, in large measure negatively, while acknowledging the potential of this self-same agency, if effectively harnessed and properly directed, to sustain essential planetary conditions through a salutary transformation of human perception, understanding and remedial action. The paper concludes that more long-term historical analyses of cultures and environments need to be undertaken at various scales. Past cases do not offer perfect analogues for the future, but they can contribute to a better understanding of how resilience and vulnerability occur, as well as how they may be compromised or mitigated.

This paper demonstrates the use of tephrochronology in dating the earliest archaeological evidence for the settlement of Iceland. This island was one of the last places on Earth settled by people and there are conflicting ideas about the pace and scale of initial colonisation. Three tephra layers, the Landnam (‘land-taking’) tephra layer (A.D. 877 ± 1), the Eldgja tephra (A.D. 939) and the recently dated V-Sv tephra (A.D. 938 ± 6) can be found at 58% of 253 securely-dated early settlement sites across the country. The presence of the tephras permits both a countrywide comparison, and a classification of these settlement sites into pre-Landnam, Landnam and post-Landnam. The data summarised here for the first time indicate that it will be possible to reconstruct the tempo and development of the colonisation process in decadal resolution by more systematically utilising the dating potential of tephrochronology.

Financial support was provided by the National Science Foundation of America through grants 1202692 and 1249313, the Carnegie Trust for the Universities of Scotland through a grant to RTS, and the NERC Doctoral Training Partnership PhD studentship NE/L002558/1 to PT. We explore developments in tephra science that consider more than chronology, using case studies. Volcanic processes and prevailing weather conditions determine the distribution of tephra deposits immediately after an eruption, but as these freshly fallen tephra become part of the stratigraphic record, the thickness, morphology and definition of the layers they form changes, reflecting the interplay of the tephra, Earth surface processes, topography and vegetation structure, plus direct or indirect modification caused by people and animals. Once part of the stratigraphic record, further diagnostic changes can happen to the morphology of tephra layers, such as the creation of over folds by cryoturbation. Thus, tephra layers may contain proxy evidence of both past surface environments and subsurface processes. Transformations of tephra deposits can complicate the reconstruction of past volcanic processes and make the application of classical tephrochronology as pioneered by Thorarinsson (Sigurður Þórarinsson in Icelandic) challenging. However, as Thorarinsson also noted, novel sources of environmental data can exist within transformed tephra sequences that include the spread or removal of tephra, variations in layer thickness and internal structures, the nature of contact surfaces and the orientation of layers. Postprint

Understanding the chronology of Norse settlement is crucial for deciphering the archaeology of many sites across the North Atlantic region and developing a timeline of human-environment interactions. There is ambiguity in the chronology of settlements in areas such as the Northern Isles of Scotland, arising from the lack of published sites that have been scientifically dated, the presence of plateaus in the radiocarbon calibration curve, and the use of inappropriate samples for dating. This novel study uses four absolute dating techniques (AMS radiocarbon, tephrochronology, spheroidal carbonaceous particles and archaeomagnetism) to date a Norse house (the “Upper House”), Underhoull, Unst, Shetland Isles and to interpret the chronology of settlement and peat which envelops the site. Dates were produced from hearths, activity surfaces within the structure, and peat accumulations adjacent to and above the structure. Stratigraphic evidence was used to assess sequences of dates within a Bayesian framework, constraining the chronology for the site as well as providing modelled estimates for key events in its life, namely the use, modification and abandonment of the settlement. The majority of the absolute dating methods produced consistent and coherent datasets. The overall results show that occupation at the site was not a short, single phase, as suggested initially from the excavated remains, but instead a settlement that continued throughout the Norse period. The occupants of the site built the longhouse in a location adjacent to an active peatland, and continued to live there despite the encroachment of peat onto its margins. We estimate that the Underhoull longhouse was constructed in the period cal. AD 805–1050 (95% probability), and most probably in cal. AD 880–1000 (68% probability). Activity within the house ceased in the period cal. AD 1230–1495 (95% probability), and most probably in cal. AD 1260–1380 (68% probability). The Upper House at Underhoull provides important context to the expansion and abandonment of Norse settlement across the wider North Atlantic region.

Accurately dating when people first colonized new areas is vital for understanding the pace of past cultural and environmental changes, including questions of mobility, human impacts and human responses to climate change. Establishing effective chronologies of these events requires the synthesis of multiple radiocarbon (14C) dates. Various “chronometric hygiene” protocols have been used to refine 14C dating of island colonization, but they can discard up to 95% of available 14C dates leaving very small datasets for further analysis. Despite their foundation in sound theory, without independent tests we cannot know if these protocols are apt, too strict or too lax. In Iceland, an ice core-dated tephrochronology of the archaeology of first settlement enables us to evaluate the accuracy of 14C chronologies. This approach demonstrated that the inclusion of a wider range of 14C samples in Bayesian models improves the precision, but does not affect the model outcome. Therefore, based on our assessments, we advocate a new protocol that works with a much wider range of samples and where outlying 14C dates are systematically disqualified using Bayesian Outlier Models. We show that this approach can produce robust termini ante quos for colonization events and may be usefully applied elsewhere.

The Mývatn area in northeast Iceland has been occupied by farming communities since the arrival of Viking Age settlers in the late ninth century. Despite its inland location and relatively high elevation, this lake basin was affected by continuous human occupation through periods of harsh climate, volcanic eruptions, epidemics, and world system impacts. Mývatn’s residents have practised farming, fishing, egg-collecting, and hunting activities for over a millennium. They managed the landscape and its resources with the use of traditional knowledge, which included the story of the troll woman, Kraka, who lived in a cave in the mountain Blafjall (“Blue Mountain”). The story of Kraka and the river Kraka that bears her name provides a striking metaphor for the landscape history including water resources and environmental changes the agricultural community sustained over time.

Financial support was provided by 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’ (both to AJD). Volcanologists often use terrestrial tephra layers to reconstruct volcanic eruptions. However, the conversion of fresh tephra deposits into tephra layers is poorly understood. To address this knowledge gap, we surveyed tephra layers emplaced by the 1980 eruption of Mount St Helens, USA (MSH1980) and the 1947 eruption of Hekla, Iceland (H1947). We compared our measurements with observations made shortly after the 1947 and 1980 eruptions, to calibrate the subsequent transformation of the tephra deposit. We expected the tephra layers to retain the broad characteristics of the original deposits, but hypothesized a) changes in thickness and mass loading due to re-working, and b) positive correlations between thickness and vegetation density. We observed some systematic changes in tephra layer properties with distance from the vent and the main plume axis. However, the preservation of the layers varied both between and within our survey locations. Closed coniferous forest appeared to provide good conditions for the preservation of the MSH1980 tephra, as expected; preservation of the H1947 deposit in sparsely vegetated parts of Iceland was much more variable. However, preservation of the MSH1980 deposit in sparsely vegetated areas of eastern Washington State was also excellent, possibly due to biocrust formation. We concluded that the preservation of tephra layers is sensitive to surface conditions at the time of the eruption. These findings have implications for the reconstruction of past eruptions where eruption plumes span regions of variable surface cover. Postprint

We argue that the deep time perspectives offered by historical disciplines, such as archaeology and history, provide important human-scale data about climate-adaptation over long timescales, and that these insights are currently lacking in global change research and Intergovernmental Panel on Climate Change reports. Pre-modern societies are not comparable with contemporary societies, but the completed experiments they represent can offer evidence of the consequences of climate change, the challenges of uncertainty and socio-cultural limits to adaptation. The limited visibility of data on long-term human interactions with climate change in global change research could be overcome through a ‘new social contract’, a two-way movement between global change and historical disciplines to, 1) make use of, and apply, historical data to contemporary climate-related challenges, 2) design robust interdisciplinary, and transdisciplinary research, 3) publish synthesised research in high-impact climate-adaptation journals, and 4) communicate research to the public in cultural history museums.

Financial support was provided by 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 support of the Carnegie Trust for the Universities of Scotland. Our aim is to understand the significance of slope position, slope angle and the interplay between slopes and vegetation in influencing the ways in which tephra layers may be preserved, thickened or thinned within the Quaternary stratigraphic record. This matters because tephra layers are used to reconstruct volumes of past volcanic eruptions and assess both past and future risks, hazards and impacts. This study uses modern data to better understand the formation of the palaeoenvironmental record and evaluates a data set of > 5500 tephra layer thickness measurements across a range of slopes and vegetation types in Iceland and Washington State, USA. We measured tephra layers formed in October 1918, March 1947, May 1980, April 2010 and May 2011 across moderate slopes (< 35°). Holding vegetation communities constant, location on slope had no systematic impact on mean tephra layer thickness. Holding slopes constant (< 5°), we observed systematic modifications of initial fallout thickness in areas of different vegetation types, with layers both thinning and thickening in areas of partial vegetation cover, and thickening within taller vegetation. This has implications for the interpretation of Quaternary environmental record and the reconstruction of past volcanic fallout across areas of varied relief and strong vegetation gradients, where vegetation structure is patchy and topography is variable. Sloping sites with a consistent vegetation cover may produce the most reliable stratigraphic records of fallout whereas flat sites with varied vegetation might not. Postprint

During the Viking Age, Norse peoples established settlements across the North Atlantic, colonizing the pristine and near-pristine landscapes of the Faroe Islands, Iceland, Greenland, and the short-lived Vinland settlement in Newfoundland. Current North Atlantic archaeological research themes include efforts to understand human adaptation and impact in these environments. For example, early Icelandic settlements persisted despite substantial environmental impacts and climatic change, while the Greenlandic settlements were abandoned ca. AD 1450 in the face of similar environmental degradation. The Norse settlers utilized both imported domestic livestock and natural fauna, including wild birds and aquatic resources. The stable isotope ratios of carbon and nitrogen (expressed as δ13C and δ15N) in archaeofaunal bones provide a powerful tool for the reconstruction of Norse economy and diet. Here we assess the δ13C and δ15N values of faunal and floral samples from sites in North Iceland within the conte...

It is often assumed that the colonisation of Greenland by Norse settlers in c. A.D. 985 had a sudden and dramatic effect on the environment, involving substantial vegetation clearance and environmental degradation. Consequently, it has been argued that charcoal-rich horizons, visible in many sections in Greenland, represent the initial burning of the vegetation by Norse farmers to create land suitable for agriculture. In this study a charcoal-rich layer, visible in a modern drainage ditch beside the Norse farm of Ø69, was analysed using archaeobotany, sedimentary analysis and radiocarbon dating to test the date and formation processes of the horizon. It is demonstrated that the charcoal-rich layer at Ø69 was not derived from in situ vegetation burning in the 10th century and concluded that the layer was probably formed by the addition of midden material to the infields around Ø69 in the 13th and 14th centuries cal AD, perhaps as part of a soil amendment strategy. It is argued that caution must be exercised when interpreting charcoal-rich horizons as time-specific chronological markers in palaeoenvironmental sequences in Greenland.

Tephra layers can form useful age-equivalent stratigraphic markers for correlating palaeoenvironmental sequences and they provide information about the spatio-temporal nature of past volcanic ash fall events. The use of microscopic ‘cryptotephra’ layers has both increased the stratigraphic resolution of tephra sequences in proximal areas and extended the distal application of tephrochronology to regions of the world situated far from volcanoes. Effective tephrochronology requires the discrimination between in situ tephra deposited directly from volcanic plumes and tephras that have been remobilised since their initial deposition. We present tephrostratigraphic and glass chemistry data from two proximal peat profiles (one lowland, one upland) from the Shetland Islands, UK. Both profiles contain the Hekla-Selsund tephra (deposited c. 1800–1750 cal. BC), whilst the Hekla 4 ash (c. 2395–2279 cal. BC) is present in the upland record. Overlying the Hekla-Selsund tephra are a number of distinct peaks in tephra shard abundance. The geochemistry of these layers shows that they represent re-working of the Hekla 4 and Hekla-Selsund layers rather than primary air-fall deposits. Pollen analysis of the peat sequences illustrates that these re-deposited tephra layers are coincident with a rise in heather-dominated vegetation communities (heath and/or moorland) and a subsequent intensification of burning in the landscape. We suggest that burning caused increased erosion of peats resulting in the remobilisation of tephra shards. The study demonstrates both the need for caution and the opportunities created when applying tephrochronologies in regions heavily affected by past human activity that contain both reworked tephra layers and in situ fallout.

This paper considers the changes in education and capacity building that are needed in response to environmental and social challenges of the 21st Century. We argue that such changes will require more than adjustments in current educational systems, research funding strategies, and interdisciplinary collaborations. Instead, it calls for a deeper questioning of the assumptions and beliefs that frame both problems and solutions. We first discuss the challenges of transforming education and capacity building within five key arenas: interdisciplinary research; university education systems; primary and secondary education systems; researchers from the developing world; and the public at large and politicians. Our starting point is that any type of revolution that is proposed in response to global change is likely to reflect the educational perspectives and paradigms of those calling for the revolution. We differentiate between a circular revolution (as in the “plan-do-check-act cycle” often used in change management) versus an axial revolution (moving to a different way of thinking about the issues), arguing that the latter is a more appropriate response to the complex transdisciplinary challenges posed by global environmental change. We present some potential tools to promote an axial revolution, and consider the limits to this approach. We conclude that rather than promoting one large and ideologically homogenous revolution in education and capacity building, there is a need for a revolution in the way that leaders working with education and capacity building look at systems and processes of change. From this perspective, transformative learning may not only be desirable, but critical in responding to the challenges posed by global environmental change.

The interplay of human actions and natural processes over varied spatial and temporal scales can result in abrupt transitions between contrasting land surface states. Understanding these transitions is a key goal of sustainability science because they can represent abrupt losses of natural capital. This paper recognizes flickering between alternate land surface states in advance of threshold change and critical slowing down in advance of both threshold changes and noncritical transformation. The early warning signals we observe are rises in autocorrelation, variance, and skewness within millimeter-resolution thickness measurements of tephra layers deposited in A.D. 2010 and A.D. 2011. These signals reflect changing patterns of surface vegetation, which are known to provide early warning signals of critical transformations. They were observed toward migrating soil erosion fronts, cryoturbation limits, and expanding deflation zones, thus providing potential early warning signals of land surface change. The record of the spatial patterning of vegetation contained in contemporary tephra layers shows how proximity to land surface change could be assessed in the widespread regions affected by shallow layers of volcanic fallout (those that can be subsumed within the existing vegetation cover). This insight shows how we could use tephra layers in the stratigraphic record to identify “near misses,” close encounters with thresholds that did not lead to tipping points, and thus provide additional tools for archaeology, sustainability science, and contemporary land management.

The hugely disruptive Eyjafjallajokull eruptions of 2010 AD are well known, but the recent history of the volcano is not, which compromises both Icelandic and international hazard assessments and risk planning. This paper identifies and dates the floods caused by two flank eruptions (the c. 920 AD eruption of the Skerin ridge and 6–7th century AD activity around Miðtungugil) and clarifies understanding of c. 6th century AD central vent eruption. These specific contributions to volcanic history are used to illustrate applications of tephrochronology with widespread relevance: how to date eruptions that generate little tephra, better understand the flood hazards presented by glaciated, mountainous volcanoes and the relationship between long-term patterns of activity in neighbouring volcanoes, in this case Eyjafjallajokull and its close (and much larger) neighbour, the volcano Katla. Copyright © 2013 John Wiley & Sons, Ltd.

The research was funded by a grant from the National Science Foundation to AJD (award number 1249313). The factors that influence tephra layer taphonomy are poorly understood, but vegetation cover is likely to play a role in the preservation of terrestrial tephra deposits. The impact of vegetation on tephra layer preservation is important because: 1) the morphology of tephra layers could record key characteristics of past land surfaces and 2) vegetation-driven variability in tephra thickness could affect attempts to infer eruption and dispersion parameters. We investigated small- (metre-) scale interactions between vegetation and a thin (

Vegetation cover mediates a number of important geomorphological processes. However, the effect of different vegetation types on the retention of fine aeolian sediment is poorly understood. We investigated this phenomenon, using the retention of fine, pyroclastic material (tephra) from the 2011 eruption of the Grímsvötn volcano, Iceland, as a case study. We set out to quantify structural variation in different vegetation types and to relate structural metrics to the thickness of recently deposited volcanic ash layers in the sedimentary section. We utilised a combination of vegetation and soil surveys, along with photogrammetric analysis of vegetation structure. We found that indices of plant community composition were a poor proxy for vegetation structure and were largely unrelated to tephra thickness. However, structural metrics, derived from photogrammetric analysis, were clearly related to variations in tephra layer thickness at a landscape scale and tephra layers under shrub patches were significantly thicker than those outside the shrub canopy. We therefore concluded that a) vegetation cover was a critical factor in the retention of fine aeolian sediment for deposit depths up to few centimetres and b) structural variation in vegetation cover played a major role in determining the configuration of tephra deposits in the sedimentary section. These findings have implications for the analysis of ancient volcanic eruptions and archaeological/palaeoenvironmental reconstructions based on the interpretation of tephra deposits. Furthermore, they present the possibility that the detailed form of tephra layers may be used as a proxy for palaeo vegetation structure. Postprint

Recent research in ecology suggests that generic indicators, referred to as early warning signals (EWS), may occur before significant transformations, both critical and non-critical, in complex systems. Up to this point, research on EWS has largely focused on simple models and controlled experiments in ecology and climate science. When humans are considered in these arenas they are invariably seen as external sources of disturbance or management. In this article we explore ways to include societal components of socio-ecological systems directly in EWS analysis. Given the growing archaeological literature on ‘collapses,’ or transformations, in social systems, we investigate whether any early warning signals are apparent in the archaeological records of the build-up to two contemporaneous cases of social transformation in the prehistoric US Southwest, Mesa Verde and Zuni. The social transformations in these two cases differ in scope and severity, thus allowing us to explore the contexts under which warning signals may (or may not) emerge. In both cases our results show increasing variance in settlement size before the transformation, but increasing variance in social institutions only before the critical transformation in Mesa Verde. In the Zuni case, social institutions appear to have managed the process of significant social change. We conclude that variance is of broad relevance in anticipating social change, and the capacity of social institutions to mitigate transformation is critical to consider in EWS research on socio-ecological systems.

This paper reflects on the application of tephrochronology in geomorphology. A common use of tephra layers is to define isochrons and use them to date environmental records. Applications of tephrochronology with the greatest practical utility, however, involve both classic isochrons (layers with an extensive distribution, distinctive well-characterised properties and good independent dating) and all other tephras present, including poorly-identified, unprovenanced and re-mobilised units that define time transgressive horizons. The effective use of this ‘total tephrochronology’ requires replication across multiple sites, the clear identification of primary tephra deposits and re-mobilised deposits, combined with a good understanding of when tephra deposits truly define isochrons. Large scale replication of tephra stratigraphy is possible (and desirable) with terrestrial sequences, and can offer a detailed understanding of both geomorphological processes and human interactions with the environment. It is possible to use sequences of unprovenanced tephras as a ‘barcode’ to undertake local correlations and refine the application of well-known marker horizons to environmental records. High frequency and high resolution measurement of both the units between tephra layers and the tephra layers themselves can identify subtle shifts in landscape stability and land use.

High resolution records of sediment accumulation are necessary to evaluate subtle temporal and spatial variations in sediment flux, especially in the context of decadal-scale human–environment interactions. Digital photography using consumer-grade cameras may be used to gather thousands of stratigraphic measurements to ± 1 mm (potentially equivalent to ± 2 years of accumulation) and provide data amenable to statistical manipulation. This new approach is illustrated with an evaluation of 15th century landscape change in Iceland. High resolution measurements show that apparent ‘spikes’ in accumulation after episodes of plague are an artefact of lower resolution measurements (± 2.5 mm) over decadal periods. Regional records show little change in sediment accumulation rates after the plagues but key local records made possible using this new methodology reveal that the period ad 1389–1416 (encompassing the plague outbreak of ad 1402) had some of the lowest sediment accumulation rates since settlement of the island. This new approach to landscape assessment indicates that in this pastoralist community the aftermath of human mortality rates of 50–60% saw no development of feral sheep populations or a switch to less labour-intensive wool production. The implication is that cattle production was maintained and the relative easing of landscape impacts could explain the lag between 14th century climatic deterioration and 18th century increases in landscape change.

In debates on societal collapse, Iceland occupies a position of precarious survival, defined by not becoming extinct, like Norse Greenland, but having endured, sometimes by the narrowest of margins. Classic decline narratives for late medieval to early modern Iceland stress compounding adversities, where climate, trade, political domination, unsustainable practices, and environmental degradation conspire with epidemics and volcanism to depress the Icelanders and turn the once-proud Vikings and Saga writers into one of Europe's poorest nations. A mainstay of this narrative is the impact of incidental setbacks such as plague and volcanism, which are seen to have compounded and exacerbated underlying structural problems. This research shows that this view is not correct. We present a study of landscape change that uses 15 precisely dated tephra layers spanning the whole 1,200-y period of human settlement in Iceland. These tephras have provided 2,625 horizons of known age within 200 stratigraphic sections to form a high-resolution spatial and temporal record of change. This finding shows short-term (50 y) declines in geomorphological activity after two major plagues in A.D. 15th century, variations that probably mirrored variations in the population. In the longer term, the geomorphological impact of climate changes from the 14th century on is delayed, and landscapes (as well as Icelandic society) exhibit resilience over decade to century timescales. This finding is not a simple consequence of depopulation but a reflection of how Icelandic society responded with a scaling back of their economy, conservation of core functionality, and entrenchment of the established order.

A number of recent studies of the UK coastal environment have assessed the 14C marine radiocarbon reservoir effect (MRE) via quantification of ΔR values for several periods throughout the Holocene using marine mollusc shells. However, none have employed fish bone as the marine sample, and the importance of being able to use this material as a reliable dating tool is evident when considering the boom in the British fish trade during the first millennium AD, the so-called ‘fish event horizon’, and the corresponding volume of fish remains that appear in the archaeological record from this time. This study compares ΔR values derived using the multiple paired sample approach employing burnt cereal grain (Hordeum sp.) as the terrestrial sample and either fish bone [North Sea cod (Gadus morhua)] or marine shell [limpet (Patella vulgata)] as the marine sample. The results show a general trend of increasing ΔR for the fish bone compared to shell, however, the differences are not statistically significant when the standard error for predicted values is used as the measure of variability in the ΔR values.

Currently, there is significant ongoing research into the temporal and spatial variability of marine radiocarbon reservoir effects (MREs) through quantification of ΔR values. In turn, MRE studies often use large changes in ΔR values as proxies for changes in ocean circulation. ΔR values are published in a variety of formats with variations in how the errors on these values are calculated, making it difficult to identify trends or to compare values, unless the method of calculating the ΔR is explicitly described or all of the data are made available in the publication. This paper demonstrates the large range in ΔR values (+34 to −122) that can be obtained from a single, secure archaeological context when using the multiple paired sample approach, despite the fact that the terrestrial entities were of statistically indistinguishable 14C ages, as were the marine samples. This demonstrates the inherent variability in the ΔR calculations themselves and we propose that, together with calculation of mean ΔR, the distribution of ΔR values should be displayed, e.g. as histograms in order to illustrate the full data range. This spread is only apparent when employing a multiple paired sample approach as the uncertainty derived on a single pair of samples, taking account only of the errors on the individual 14C ages, will never truly represent the overall variability in ΔR that results from the intrinsic variability in the population of 14C ages in samples that might have been used. Consequently, ΔR values and the associated uncertainty calculated from single pairs should be treated with some caution. We propose that, where possible, when using paired archaeological samples, that a multiple paired approach should be employed as it will test the context security of the material used in the ΔR calculations. When summarizing the values by the weighted average, we also propose that the standard error for predicted values should be employed as this will fully encompass the uncertainty of a future ΔR calculation, using different samples for a similar time and location. Finally, we encourage future publishing of ΔR values using the histogram format, making all of the data available. This will help ensure that ΔR values are comparable across the literature and should provide a framework for standardization of publication methods.

The marine radiocarbon reservoir effect (MRE) occurs as a spatially and temporally dependent variable owing to localized changes in oceanic water composition. This study investigates ΔR values (deviations from the global average MRE whose ΔR = 0) during the period 500–1350 BP for the east coast of Scotland, where a complex estuarine system exists that drains into the semi-enclosed North Sea basin. Due to the availability of suitable archaeological samples, the data set has a distinct Medieval focus that spans the area from Aberdeen in the north to East Lothian in the south. Many of the ΔR values are not significantly different from 0 (the global average), but there are occasional excursions to negative values (max –172 ± 20) indicating the presence of younger water. These values show greater variability compared to other published data for this general region, suggesting that considerable care must be taken when dating marine derived samples from archaeological sites on the east coast of Scotland.

Lake Mývatn is an interior highland lake in northern Iceland that forms a unique ecosystem of international scientific importance and is surrounded by a landscape rich in archaeological and paleoenvironmental sites. A significant freshwater reservoir effect (FRE) has been identified in carbon from the lake at some Viking (about AD 870–1000) archaeological sites in the wider region (Mývatnssveit). Previous accelerator mass spectrometry (AMS) measurements indicated this FRE was about 1500–1900 14C yr. Here, we present the results of a study using stable isotope and 14C measurements to quantify the Mývatn FRE for both the Viking and modern periods. This work has identified a temporally variable FRE that is greatly in excess of previous assessments. New, paired samples of contemporaneous bone from terrestrial herbivores and omnivores (including humans) from Viking sites demonstrate at least some omnivore diets incorporated sufficient freshwater resources to result in a herbivore-omnivore age offset of up to 400 14C yr. Modern samples of benthic detritus, aquatic plants, zooplankton, invertebrates, and freshwater fish indicate an FRE in excess of 5000 14C yr in some species. Likely geothermal mechanisms for this large FRE are discussed, along with implications for both chronological reconstruction and integrated investigation of stable and radioactive isotopes.

We investigated surface ocean–atmosphere 14C offsets for the later Holocene at eight locations in the eastern North Atlantic. This resulted in 11 new ΔR assessments for the west coast of Ireland, the Outer Hebrides, the north coast of the Scottish mainland, the Orkney Isles and the Shetland Isles over the period 1300–500 BP. Assessments were made using a robust Multiple Paired Sample (MPS) approach, which is designed to maximize the accuracy of ΔR determinations. Assessments are placed in context with other available data to enable reconstruction of a realistic picture of surface ocean 14C activity over the Holocene period within the North Atlantic region.

With reference to 18 tephra isochrones, we present six reconstructions of landscapes in South Iceland at precise times through the last 1200 years and develop three related models of soil erosion. Before the late ninth century A.D., the landscapes of Iceland were without people and resilient to natural processes. The initial impact of human settlement in the ninth century AD was most profound in ecologically marginal areas, where major anthropogenic modifi cations of the ecology drove geomorphological change. In the uplands, overgrazing contributed to the formation of a dense patchwork of breaks in the vegetation cover where soil erosion developed and resulted in the rapid denudation of large areas. As the upland soils were shallow (generally 2 m) involved a lower spatial density of eroding fronts and a slower loss of soil cover, but a much greater movement of sediment. Land-management strategies, changes in species patterns of plant communities, extreme weather events, and climate changes have combined in differing degrees to initiate and drive rates of soil erosion. Sensitivity to change and the crossing of erosion thresholds has varied through time. The record of soil erosion has major implications for both archaeology and contemporary land management.

Two glaciers at Eyjafjallajökull, south Iceland, provide a record of multiple episodes of glacier advance since the Sub-Atlantic period, ca. 2000 yr ago. A combination of tephrochronology and lichenometry was applied to date ice-marginal moraines, tills and meltwater deposits. Two glacier advances occurred before the 3rd century AD, others in the 9th and 12th centuries bracketing the Medieval Warm Period, and five groups of advances occurred between AD 1700 and 1930, within the Little Ice Age. The advances of Eyjafjallajökull before the Norse settlement (ca. AD 870) were synchronous with other glacier advances identified in Iceland. In contrast, medieval glacier advances between the 9th and 13th centuries are firmly identified for the first time in Iceland. This challenges the view of a prolonged Medieval Warm Period and supports fragmentary historical data that indicate significant medieval episodes of cooler and wetter conditions in Iceland. An extended and more detailed glacier chronology of the mid- and late Little Ice Age is established, which demonstrates that some small outlet glaciers achieved their Little Ice Age maxima around AD 1700. While Little Ice Age advances across Iceland appear to synchronous, the timing of the maximum differs between glacier type and region.