Thomas H. McGovern

Interdisciplinary investigations of the end of the Norse Western Settlement in Greenland

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 This study employs an interdisciplinary approach combining historical documents, detailed archaeological investigations, and a high-resolution proxy climate record from the Greenland Ice Sheet Project 2 (GISP2) to investigate possible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.

Bioarchaeological and climatological evidence for the fate of Norse farmers in medieval Greenland

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.

Cultural adaptation, compounding vulnerabilities and conjunctures in Norse Greenland

Norse Greenland has been seen as a classic case of maladaptation by an inflexible temperate zone society extending into the arctic and collapse driven by climate change. This paper, however, recognizes the successful arctic adaptation achieved in Norse Greenland and argues that, although climate change had impacts, the end of Norse settlement can only be truly understood as a complex socioenvironmental system that includes local and interregional interactions operating at different geographic and temporal scales and recognizes the cultural limits to adaptation of traditional ecological knowledge. This paper is not focused on a single discovery and its implications, an approach that can encourage monocausal and environmentally deterministic emphasis to explanation, but it is the product of sustained international interdisciplinary investigations in Greenland and the rest of the North Atlantic. It is based on data acquisitions, reinterpretation of established knowledge, and a somewhat different philosophical approach to the question of collapse. We argue that the Norse Greenlanders created a flexible and successful subsistence system that responded effectively to major environmental challenges but probably fell victim to a combination of conjunctures of large-scale historic processes and vulnerabilities created by their successful prior response to climate change. Their failure was an inability to anticipate an unknowable future, an inability to broaden their traditional ecological knowledge base, and a case of being too specialized, too small, and too isolated to be able to capitalize on and compete in the new protoworld system extending into the North Atlantic in the early 15th century.

Northern Islands, human error, and environmental degradation: A view of social and ecological change in the Medieval North Atlantic

Between ca. 790 and 1000 AD, Scandinavian settlers occupied the islands of the North Atlantic: Shetland, the Orkneys, the Hebrides, the Faroes, Iceland, and Greenland. These offshore islands initially supported stands of willow, alder, and birch, and a range of non-arboreal species suitable for pasture for the imported Norse domestic animals. Overstocking of domestic animals, fuel collection, ironworking, and construction activity seems to have rapidly depleted the dwarf trees, and several scholars argue that soil erosion and other forms of environmental degradation also resulted from Norse landuse practices in the region. Such degradation of pasture communities may have played a significant role in changing social relationships and late medieval economic decline in the western tier colonies of Iceland and Greenland. This paper presents simple quantified models for Scandinavian environmental impact in the region, and suggests some sociopolitical causes for ultimately maladaptive floral degradation.

Fuel resource utilisation in landscapes of settlement

One little understood aspect of the settlement and colonisation of Iceland is fuel resource use. In this paper we identify fuel ash residues from temporally constrained middens at two contrasting settlement age sites in Mývatnssveit, northern Iceland, one high status, the other low status and ultimately abandoned. Fuel residues derived from experimental combustion of historically defined fuel resources are used to provide control for thin section micromorphology and complementary image analyses of fuel residue materials found in the midden deposits. The results suggest that fuel resources utilised at the time of settlement were for both low temperature and high temperature use, and included a mix of birch and willow wood, peat, mineral-based turf and cow dung. There are, however, marked variations in the mix of fuel resources utilised at the two sites. This is considered to reflect social regulation of fuel resources and socially driven changes to local and regional environments that may have contributed to the success or failure of early settlement sites in Iceland.

Raiding the Landscape: Human Impact in the Scandinavian North Atlantic

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.

Abandoned Farms, Volcanic Impacts, and Woodland Management: Revisiting Þjórsárdalur, the “Pompeii of Iceland”

Geomorphological maps and nine soil profiles containing 92 tephra layers have been examined to explore the nature of medieval environmental change in Þjórsárdalur, 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 Þjórsárdalur resulting in localized landscape stabilization that continued throughout the following Little Ice Age episodes of climate deterioration.

Temporal and Spatial Variations in Freshwater 14C Reservoir Effects: Lake Mývatn, Northern Iceland

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.

Reservoirs and radiocarbon: C-14 dating problems in Myvatnssveit, northern Iceland

This paper examines 2 potential sources of the radiocarbon offset between human and terrestrial mammal (horse) bones recovered from Norse (~AD 8701000) pagan graves in Mvatnssveit, 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 Mvatnssveit and 1 site on the north Icelandic coast. These produced 3 new Δ R values for the north coast of Iceland, indicating a Δ R of 106 10 14C yr at AD 868985, and of 144 28 14C yr at AD 12801400. These values are statistically comparable and give an overall weighted mean Δ R of 111 10 14C yr. The freshwater reservoir effect was similarly quantified using freshwater fish bones from a site in Mvatnssveit. 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 Mvatn. We conclude the following: i) some of the Norse inhabitants of Mvatnssveit 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 Peopling of Iceland

In recent years intensive archaeological research on the Viking Age in Iceland has produced much new evidence supporting a late 9th century colonization of the country. It can now be stated not only that people had arrived in Iceland before AD 870 but also that comprehensive occupation only took place after that date. The increased temporal resolution of the new archaeological data not only allows the characterization of different phases of the colonization but also supports assessments of the scale and rate of the immigration. In this paper we report the results of fieldwork in Mývatnssveit, NE-Iceland, where more than 30 sites have been investigated, ranging from small test trenches to large-scale open area excavations. We argue, based on the Mývatnssveit data, that a minimum of 24,000 people must have been transported to Iceland in less than 20 years to account for the dates and density of the Mývatn sites. In the absence, so far, of comparable data from other parts of the country these conclusions must remain hypothetical but if supported by further work they will have significant implications for our understanding of first peopling of Holocene farming populations in general and of Viking Age migrations in particular.