Papers by Michelle de Gruchy
Quaternary Science Reviews, 2025
Land use and land cover (LULC) changes have important biophysical and biogeochemical effects on c... more Land use and land cover (LULC) changes have important biophysical and biogeochemical effects on climate via a variety of mechanisms. Several climate modelling studies have demonstrated the impact of LULC scenarios on past climate reconstructions. Testing the impact of anthropogenic land use on mid-Holocene climate thus requires reconstructions of land use that accurately reflect this time frame. To address these concerns, the PAGES LandCover6k working group aims to create data-driven gridded global reconstructions of land use and land cover to provide the climate modelling community with inputs for sensitivity testing of the impact of LULC changes on global climate. As one of the earliest global centres of domestication, agricultural production, and population nucleation, Southwest Asia represents one of the areas of the world expected to display the greatest land use impact and human-induced land cover change at 6 kya, and is therefore critical for the mid-Holocene time frame. Here, we reconstruct land use for Southwest Asia for the 6 kya time frame at a regional scale. We draw on environmental data to reconstruct the range of possible land uses within each particular environment and on archaeological and historical data to reconstruct actualized land use. We then compare this reconstruction to common global LULC models, including the most recent HYDE and KK10 iterations. The reconstruction presented here differs from these previous reconstructions in its methodological approach, spatial extent and resolution. It also differs from both models in population density distribution and land use allocation. While the output of our reconstruction is generally more similar to HYDE 3.2 than KK10, particularly in terms of reconstructed pastoral land use, we model greater agricultural land use than HYDE across the entire region, and less land use overall compared with KK10. The paper provides a method for systematically incorporating archaeological data into models of past land use and demonstrates the value of such an approach for enhancing empirical validity.
The 4.2kyr event saw major changes in civilizations across the world, often attributed to climate... more The 4.2kyr event saw major changes in civilizations across the world, often attributed to climate change and widespread drought. Indeed, there are high quality palaeohydrological proxies that seem to document a significant drying at this time in Egypt, the Indus Valley and in the Near East. In Mesopotamia, settlements were abandoned, agricultural practices shifted and the Akkadian Empire ended. Climate model simulations covering 5000-3000 years ago are able to reproduce much of the evidence for Holocene climate change and some of the key reductions in mid-late Holocene precipitation. However, unlike some other regions, the annual mean rainfall in Mesopotamia at 4.2kyr is similar to the adjoining millennia. The climate model simulates significant droughts during this time, but these are within the range seen both before and after.</p><p>The end of the middle Holocene saw rapid population growth in Mesopotamia, with significant urban centres putting pressure on local resources. Although the models suggest no significant change in climate, the archaeological evidence shows the exploitation of a dryer landscape, both in existing sites and new urban centres in dryer regions. This time also sees changing agricultural practices and the loss of available sources of wood. Vegetation models suggest little impact of climate change on the natural landscape, although drought years bring major losses in net primary productivity. However, human activities in Mesopotamia could have affected the landscape and exacerbated the impacts of existing drought cycles. We suggest that an unexceptional drought, combined with a large population and anthropogenic impacts on the landscape contributed to significant societal change in Mesopotamia at 4.2kyr.</p>
The story of the hollow ways in the North Jazira began more than 5000 years ago, when the collect... more The story of the hollow ways in the North Jazira began more than 5000 years ago, when the collective footprints of people walking to and from their fields, leading their animals to pasture, and travelling between sites became so numerous that they wore away the earth and left paths still visible today. This paper reviews the potential cultural and physical processes behind the formation of hollow ways in the North Jazira, and asks to what extent formation studies may be biased by differential preservation. Whilst taphonomic processes affect all sites and features, recent landscape developments have been particularly destructive to archaeological remains. Despite this, thousands of hollow ways remain, but the reasons why they are preserved have never been examined. In short, this paper explores how the hollow ways got their form and kept them.
Supplementary Online Material for the publication Hewett, Z., de Gruchy, M., Hill, D., and Lawren... more Supplementary Online Material for the publication Hewett, Z., de Gruchy, M., Hill, D., and Lawrence, D. (forthcoming) Raincheck: A new diachronic series of rainfall maps for Southwest Asia over the Holocene. <em>Levant</em>. Included are all the necessary data files and scripts (R) needed to create the rainfall maps that are the subject of the article.
This is a recording of a presentation given at the workshop on 'Reproducible research in Arch... more This is a recording of a presentation given at the workshop on 'Reproducible research in Archaeology' at Durham University on 15th October 2021. The workshop included an introduction to what reproducibility is, why it is important for archaeological research and how you can make your research workflow reproducible. It also included some case studies demonstrating reproducible workflows used in archaeological research. This workshop was organised by Software Sustainability Institute Fellows - Alison Clarke and Emma Karoune. The slides from the presentation are available at https://doi.org/10.5281/zenodo.5564648.
Environmental Archaeology, 2021 [Peer Reviewed Journal], 2021
Quaternary International
Abstract Understanding the organisation of food production is vital for understanding ancient soc... more Abstract Understanding the organisation of food production is vital for understanding ancient societies. Multiple factors may influence decision making, including the local environmental capacity of a given area and individual and cultural preferences. This study compares zooarchaeological data from sites across the length and breadth of the Holocene Near East with modelled patterns of land use. The goal is to determine how far variation in the capacities of local landscapes impacted the choices made in animal production. Our approach allows us to investigate trends through time as well as between different regions of the Near East. The spatial and temporal scales employed also mean we can investigate the relationship between food production and climate trends. We find substantial patterning in the choices made in animal production, reflecting complex and regionally diverse production approaches. We demonstrate a prioritisation of individual and societal preferences to produce specific animals which is rarely impacted by either short or long term changes in aridity. We also find that the emergence of urban sites has a major impact on provisioning structures, and argue that the resulting organisational forms may have resulted in urban sustainability at the expense or rural sites.
Remote Sensing
This study presents the results of the first remote sensing survey of hollow ways in Southern Mes... more This study presents the results of the first remote sensing survey of hollow ways in Southern Mesopotamia between Baghdad and the Persian Gulf, primarily using the imagery in Google Earth. For archaeologists, hollow ways are important trace fossils of past human movement that inform about how people travelled in the past and what considerations were important to them as they moved through the landscape. In this study, remotely sensed hollow ways were ground-truthed and dated by association with both palaeochannels and known archaeological sites. Contextual and morphological evidence of the hollow ways indicate that they are likely the archaeological manifestation of ethnographically attested "water channels" formed through the dense reeds of marshlands in southern Iraq, not formed by traction overland like other known hollow ways. The map itself documents the first known hollow ways preserved underwater and one of the best-preserved landscapes of past human movement in the Near East.
Internet Archaeology, 2017
James (2017) 'Velocity-based terrain coecients for time-based models of human movement.', Interne... more James (2017) 'Velocity-based terrain coecients for time-based models of human movement.', Internet archaeology. (45).
Journal of Archaeological Method and Theory, 2015
The full-text may be used and/or reproduced, and given to third parties in any format or medium, ... more The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details.
International Journal of Heritage in the Digital Era, 2012
The impact of each dam on cultural heritage is enormous, affecting hundreds or even thousands of ... more The impact of each dam on cultural heritage is enormous, affecting hundreds or even thousands of sites. Dams are required, however, to offset water shortages and provide electricity for a rising global population. This short paper describes the initial outcomes of a new project, the aim of which is the production of a practical set of guidelines for cultural heritage management before and after dam construction, aimed at developers, foreign contractors, and policy-makers.
Environmental Archaeology
Quaternary Science Reviews
This paper illustrates long-term trends in human population and climate from the Late Pleistocene... more This paper illustrates long-term trends in human population and climate from the Late Pleistocene to the Late Holocene (14,000e2500 cal. yr. BP) in order to assess to what degree climate change impacted human societies in the Near East. It draws on a large corpus of archaeo-demographic data, including anthropogenic radiocarbon dates (n ¼ 10,653) and archaeological site survey (n ¼ 22,533), and 16 hydroclimatic records from cave speleothems and lake sediments. Where possible, inferred population dynamics and climatic trends have been made spatially congruent, and their relationships have been statistically tested. Demographic proxies and palaeoclimatic records have been compared for the greater Near East as a whole and for seven major geo-cultural regions (Anatolia, Arabia, Cyprus, Iran, Levant, Mesopotamia, and South Caucasus). This approach allows us to identify regionalised patterns in population and climate trends. The results suggest a clear relationship between population and climate in the Late Pleistocene and Early Holocene (14,000e8326 cal. yr. BP) with population increasing in concomitance with wetter climatic conditions. During the Middle Holocene (8326-4200 cal. yr. BP) there is an increased regionalisation of demographic patterns, followed by marked interregional contrasts in the Late Holocene (4200-2500 cal. yr. BP). We identify a decoupling of demographic and climatic trends from the Middle Holocene onwards, and relate this to the existence of more complex societies. These were less vulnerable to gradual climatic shifts due to their logistical infrastructure, social organisation and technological capacity. We also assess the impact of five Rapid Climate Changes (RCC) which occurred during the study period on population levels. Although all five RCC (the so-called 10.2 k, 9.2 k, 8.2 k, 4.2 k, and 3.2 k cal. yr. BP events) are visible to some degree in our palaeoclimatic and demographic proxies, there are marked regional variations in magnitude and duration.
PLOS ONE
The rise and fall of ancient societies have been attributed to rapid climate change events. One o... more The rise and fall of ancient societies have been attributed to rapid climate change events. One of the most discussed of these is the 4.2kya event, a period of increased aridity and cooling posited as the cause of societal changes across the globe, including the collapse of the Akkadian Empire in Mesopotamia. Studies seeking to correlate social and climatic changes around the 4.2kya event have tended to focus either on highly localized analyses of specific sites or surveys or more synthetic overviews at pan-continental scales, and temporally on the event and its aftermath. Here we take an empirical approach at a large spatial scale to investigate trends in population and settlement organization across the entirety of Northern Fertile Crescent (Northern Mesopotamia and the Northern Levant) from 6,000 to 3,000 cal BP. We use Summed Probability Distributions of radiocarbon dates and data from eighteen archaeological surveys as proxies for population, and a dataset of all settlements ov...
The late fourth millennium B.C. of Mesopotamia is best known for an expansion of material culture... more The late fourth millennium B.C. of Mesopotamia is best known for an expansion of material culture from Southern Mesopotamia known as the Uruk Expansion or Uruk Phenomenon. The precise nature of this expansion remains unknown, but at its core it evidences unprecedented levels of interregional interaction whether in the form of colonies, trade diasporas, or otherwise. This thesis uses quantitative route analysis to examine the hollow ways across the North Jazira region of northern Mesopotamia before, during, and after the Uruk Expansion in the late fourth millennium B.C. to learn more about the phenomenon. To accomplish this, new methodologies were required. A bottom up method for reconstructing land cover was developed and the first velocity-based terrain coefficients were calculated to factor both land cover and slope into the route models. Additionally, the first quantitative method for directly comparing route models to preserved routes was developed to statistically assess the si...
Environmental Archaeology
WIREs Climate Change
During the Late Chalcolithic and Early Bronze Age (c. 6500–4000 BP), the Fertile Crescent in Sout... more During the Late Chalcolithic and Early Bronze Age (c. 6500–4000 BP), the Fertile Crescent in Southwest Asia saw the earliest development of cities anywhere in the world. Climate and environmental factors are generally considered to be significant in these changes because in pre‐industrial societies they directly relate to food production and security. The emergence of cities also coincides with a decoupling of settlement and climate trends, suggesting urbanism may have enhanced the adaptive capacity of societies to withstand changing climatic conditions. Urban forms followed a variety of different trajectories, with a much more sporadic and episodic history in the dry farming plains of the North and West of the study region compared to the stable build‐up in the irrigated South. Although models dealing with urban growth have emphasized the differential access to agrarian resources as a key driver in promoting hierarchical social systems, climate has rarely been explicitly discussed. In contrast, so‐called “collapse” events brought about by extreme, but short‐lived, climate changes such as droughts have been blamed for declines in urban and rural populations, social complexity, political systems, and entire empires. However, the extent to which these “collapses” are visible in the archeological record, let alone how far they can be attributed to climate changes, is a matter of intense debate. The archeological and historical record, the variegated environmental conditions, and the deep time perspective on complexity available, make the Fertile Crescent an ideal laboratory for assessing causal links between urban formations and climate fluctuations
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Papers by Michelle de Gruchy