Jørgen Hollesen

The National Museum of Denmark · Environmental Archaeology and Materials Science

The Arctic is warming twice as fast as the global average with overlooked consequences for the preservation of the rich cultural and environmental records that have been stored for millennia in archaeological deposits. In this article, we investigate the oxic degradation of different types of organic archaeological deposits located in different cli...

Decomposition of organic carbon from thawing permafrost soils and the resulting release of carbon to the atmosphere are considered to represent a potentially critical global-scale feedback on climate change. The accompanying heat production from microbial metabolism of organic material has been recognized as a potential positive-feedback mechanism...

Growing season conditions are widely recognized as the main driver for tundra shrub radial growth, but the effects of winter warming and snow remain an open question. Here, we present a more than 100 years long Betula nana ring-width chronology from Disko Island in western Greenland that demonstrates a highly significant and positive growth respons...

The cold, wet climate of the Arctic has led to the extraordinary preservation of archaeological sites and materials that offer important contributions to the understanding of our common cultural and ecological history. This potential, however, is quickly disappearing due to climaterelated variables, including the intensification of permafrost thaw a...

Climate change may accelerate the degradation of archaeological sites in the Arctic and lead to a loss of important historical information. This study assesses the current preservation conditions and the processes controlling the physical and chemical stability of the Qajaa kitchen midden in western Greenland. Currently, the site is well protected...

Over the past decades, climate change has accelerated the deterioration of heritage sites and archaeological resources in Arctic and subarctic landscapes. At the same time, increased tourism and growing numbers of site visitors contribute to the degradation and manipulation of archaeological sites. This situation has created an urgent need for new,...

Climate change threatens archaeological sites and cultural landscapes globally. While to date, awareness and action around cultural heritage and climate change adaptation planning has focused on Europe and North America, in this article, the authors address adaptation policy and measures for heritage sites in low- and middle-income countries. Using...

Climate change is affecting archaeological sites and landscapes around the world. Increased rainfall, more frequent extreme weather events, higher temperatures and rising seas not only create new risks but also exacerbate existing vulnerabilities and threats. Building on an earlier Antiquity article that explored climate change and arctic archaeolo...

Wetland archaeological sites offer excellent but vulnerable preservation conditions. This article presents examples of threats to such sites that may be enhanced, or diminished, by climate change, discusses methods for predicting and quantifying impacts, and examines what heritage managers can do to mitigate their effects. The consequences of clima...

The Intergovernmental Panel on Climate Change has documented wide-ranging changes to the world's coasts and oceans, with significant further change predicted. Impacts on coastal and underwater heritage sites, however, remain relatively poorly understood. The authors draw on 30 years of research into coastal and underwater archaeological sites to hi...

The success and failure of past cultures across the Arctic was tightly coupled to the ability of past peoples to exploit the full range of resources available to them. There is substantial evidence for the hunting of birds, caribou and seals in prehistoric Greenland. However, the extent to which these communities relied on fish and cetaceans is und...

The success and failure of past cultures across the Arctic was tightly coupled to the ability of past people to exploit the full range of resources available to them, and to adapt to fluctuations in resource availability. There is substantial evidence for the hunting of birds, caribou and a wide range of marine mammals in pre-historic Greenland fro...

The combined effects of climate change and nutrient availability on Arctic vegetation growth are poorly understood. Archaeological sites in the Arctic could represent unique nutrient hotspots for studying the long-term effect of nutrient enrichment. In this study, we analysed a time-series of ring widths of Salix glauca L. collected at nine archaeo...

Insect defoliations are a major natural disturbance in high-latitude ecosystems and are expected to increase in frequency and severity due to current climatic change. Defoliations cause severe reductions in biomass and carbon investments that affect the functioning and productivity of tundra ecosystems. Here we combined dendro-anatomical analysis w...

The degradation of archaeological bones is influenced by many variables. The bone material itself is a composite of both organic and inorganic components, and their degradation depends on processes occurring both before and after burial, and on both intrinsic bone characteristics as well as extrinsic environmental parameters. In this study we attem...

AimsPlant growth in the Arctic is often nutrient limited due to temperature constraints on decomposition and low atmospheric input of nitrogen (N). Local hotspots of nutrient enrichment found in up to 4000-year-old archaeological deposits can be used to explore the recycling and long-term retention of nutrients in arctic ecosystems.Methods We inves...

Climate change is expected to accelerate the microbial degradation of the many extraordinary well-preserved organic archaeological deposits found in the Arctic. This could potentially lead to a major loss of wooden artefacts that are still buried within the region. Here, we carry out the first large-scale investigation of wood degradation within ar...

Vegetation is changing across the Arctic in response to increasing temperatures, which may influence archaeological sites in the region. At the moment, very little is known about how different plant species influence archaeological remains. In this study we visited 14 archaeological sites stretching across a climatic gradient from the outer coast t...

Climate change threatens many well‐preserved archaeological sites in the Arctic. Here we present the first Arctic multi‐threat assessment focusing on the Nuuk region in Greenland. Our results suggest that the majority of the 336 known archaeological sites are already exposed to impacts from microbial degradation, permafrost thaw and vegetation and...

Across the Arctic, microbial degradation is actively destroying irreplaceable cultural and environmental records that have been preserved within archaeological deposits for millennia. Because it is not possible to survey the many sites in this remote part of the world, new methods are urgently needed to detect and assess the potential degradation....

https://www.icomos.org/en/what-we-do/image-what-we-do/77-articles-en-francais/59522-icomos-releases-future-of-our-pasts-report-to-increase-engagement-of-cultural-heritage-in-climate-action

Tundra ecosystems are highly vulnerable to climate change, and climate–growth responses of Arctic shrubs are variable and altered by microsite environmental conditions and biotic factors. With warming and drought during the growing season, insect‐driven defoliation is expected to increase in frequency and severity with potential broad‐scale impacts...

Climate change has irrevocable consequences for the otherwise well-preserved archaeological deposits in the Arctic. Vegetation changes are expected to impact archaeological sites, but currently the effects are poorly understood. In this article we investigate five archaeological sites and the surrounding natural areas along a climate gradient in So...

Evaluating the rate of deterioration at archaeological sites in the Arctic presents several challenges. In West Greenland, for example, increasing soil temperatures, perennial thaws, coastal erosion, storm surges, changing microbial communities, and pioneer plant species are observed as increasingly detrimental to the survival of organic archaeolog...

Permafrost is vulnerable to rapid changes in climate, and increasing air temperatures have recently resulted in the increase of active layer thickness, thaw subsidence and warming of the underlying permafrost. Such changes have important implications for geotechnical properties and the stability of infrastructures in permafrost-affected areas. Many...

Bryggen i Bergen modtager hvert år over en million besøgende, som tiltrækkes af det stemningsfulde miljø og de karakteristiske træbygninger fra starten af 1700-tallet. Mindre synligt, men lige så vigtigt ligger der op til 11 meter tykke kulturlag under husene, som vidner om livet på Bryggen tilbage til 1000-tallet. Omfattende udgravninger i årene 1...

Monitoring of the archaeological deposits at the World Heritage Site Bryggen in Bergen has been ongoing since 2001. In latter years a large-scale project of mitigation works has been carried out, resulting in the creation of a watermanagement system aimed at raising groundwater-levels and increasing soil moisture content in areas with poor preserva...

This paper presents archaeological observations and results of palaeoecological and geo-chemical analyses of archaeological deposits from two rural sites in northernmost Norway. These are combined with climate data and the first period of continuous monitoring of soil temperature, moisture, and redox potential in sections. This data constitutes the...

This paper addresses the knowledge gap that exists in relation to understanding and quantifying the sensitivity of organic-rich archaeological deposits with respect to changes in the soil environment. Based on two case studies we demonstrate that it is possible to quantify the current decay rate in unsaturated archaeological deposits by combining d...

Oxygen is a key parameter in the degradation of archaeological material, but little is known of its dynamics in situ. In this study, 10 optical oxygen sensors placed in a 2 m deep test pit in the cultural deposits at Bryggen in Bergen have monitored oxygen concentrations every half hour for more than a year. It is shown that there is a significant...

Arctic regions contain many archaeological sites with exceptional organic preservation is due to the climate. Beyond the features and artifacts left by past humans, these sites archive the residues of human subsistence activities, as stratified layers, often spanning millennia, of the remains of animals and plants gathered from the surrounding area...

MESSAGE FROM MINISTER OF CLIMATE AND ENVIRONMENT World Heritage Site Bryggen in Bergen is one of our most important historical monuments and one of the country’s most popular tourist destinations. The Ministry of Climate and Environment has overall responsibility for the upkeep of Norway’s world heritage sites and has kept a close eye on the work a...

The sensitivity of organic-rich archaeological layers at Bryggen in Bergen, Norway, to changes in soil temperatures, water contents and oxygen concentrations is investigated. This is done by linking measurements of oxic decay at varying temperatures and water contents with on-site monitoring data using a one-pool decomposition model. The results sh...

Recent warming is expected to dramatically modify the arctic terrestrial ecosystem and woody plants growth. Many studies dealing with Arctic shrubs growth responses to temperature usually base their estimations on biomass measurements of only the above-ground segments neglecting the below-ground growth. In this context, the study of shrub-rings can...

The degradation of archaeological wood at freezing and thawing temperatures is studied at the site of Qajaa in West Greenland through a combination of environmental monitoring, measurement of oxygen consumption and microscopy of wood samples. Permanently frozen wood is still very well preserved after 2–4000 years, while wood samples that thaw every...

Archaeological materials may be extraordinarily well preserved in Arctic areas, where permanently frozen conditions in the ground slow down the decay of materials such as wood, bone, flesh, hair, and DNA. However, the mean annual air temperature in the Arctic is expected to increase by between 2·5 to 7·5°C by the end of the twenty-first century. This...

Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures as the release of AMD normally is limited by permafrost...

Thawing permafrost and the resulting mineralization of previously frozen organic carbon (C) is considered an important future feedback from terrestrial ecosystems to the atmosphere. Here, we use a dynamic process oriented permafrost model, the CoupModel, to link surface and subsurface temperatures from a moist permafrost soil in High-Arctic Greenla...

The release of Acid Mine Drainage, AMD, from mine waste rocks in Arctic areas is commonly assumed to be limited by low air temperatures and permafrost. Here we show that heat generation within a sulphidic coal mining waste rock pile in Svalbard (78°N) is sufficiently high to keep the pile warm at roughly 5 °C throughout the year despite average win...

Acid mine drainage (known as AMD) is a well-known environmental problem resulting from the oxidation of sulfidic mine waste. In cold regions, AMD is often considered limited by low temperatures most of the year and observed environmental impact is related to pollution generated during the warm summer period. Here we show that heat generation within...

Changes in the amount of soil organic carbon (SOC) stored in arctic soils may influence the global carbon cycle and be an important feedback mechanism to global climate changes. In order to estimate the carbon stock and accumulation rates at Flakkerhuk on Disko Island in West Greenland, an 1800-ha study area was divided into land cover types using...