Guiot Joel

Aix-Marseille University | AMU · Institut Pythéas - Observatoire des Sciences de l'Univers (UMS 3470)

The Mediterranean region is currently dealing with critical global challenges, including water scarcity, food and energy insecurity, and ecosystem degradation. These challenges are interconnected and are collectively referred to as the Water-Energy-Food-Ecosystems (WEFE) nexus. Climate change further exacerbates these challenges, making it necessar...

What impact did the Roman Climate Optimum (RCO) and the Late Antique Little Ice Age (LALIA) have on the rise and fall of the Roman Empire? Our article presents an agent-based modelling (ABM) approach developed to evaluate the impact of climate change on the profitability of vineyards, olive groves, and grain farms in Southern Gaul, which were the m...

Bringing together a wide array of modern scientific techniques and interdisciplinary approaches, this book provides an accessible guide to the methods that form the current bedrock of research into Roman, and more broadly ancient, wine. Chapters are arranged into thematic sections, covering biomolecular archaeology and chemical analysis, archaeobot...

The potential areal extent of agricultural crops is sensitive to climate change and its underlying drivers. To distinguish between the drivers of past variations in the Mediterranean viticulture extension since Early Antiquity and improve projections for the future, we propose an original attribution method based on an emulation of offline coupled...

The potential areal extent of agricultural crops is sensitive to climate change and its underlying drivers. To distinguish between the drivers of past variations in the Mediterranean viticulture extension since Early Antiquity and improve projections for the future, we propose an original attribution method based on an emulation of coupled climate...

Currently available data-assimilation-based reconstructions of past climate variations have only used statistical proxy system models to make the link between climate model outputs and indirect observations from tree rings. However, the linearity and stationarity assumptions of the statistical approach may have limitations. In this study, we incorp...

The potential areal extent of agricultural crops is sensitive to climate change and its underlying drivers. To distinguish between the drivers of past variations in the Mediterranean viticulture since Early Antiquity and improve projections for the future, we propose an original attribution method based on an emulation of coupled climate and ecosys...

This volume examines the multidimensional relationship between climate change and security across Mediterranean Basin states and societies, underscoring the key social, political and economic challenges of the present climate emergency and outlining possible cooperative avenues to mitigate its most adverse effects. Part of a broader research and en...

Currently available data assimilation-based reconstructions of past climate variations have only used statistical proxy system models to make the link between the climate model outputs and the indirect observations from tree rings. However, the linearity and stationarity assumptions of the statistical approach may have limitations. In this study, w...

Tree-rings are one of the most commonly used proxies for reconstructing past climates at annual resolution. The climate information is generally deduced from tree-rings using statistical relationships, but the assumed linearity and stationarity may be inadequate. Process-based models allow for non-stationarity and non-linearity; however, many chall...

Boreal Québec is one of the regions of the world where climate change has been the most marked over the past thirty years. The climate has warmed up, but also dried up, with a drop of more than 15% in annual precipitation. The situation could have serious socio-economic conse-quences as nearly 50% of the province's hydroelectric production comes pr...

Starting as early as the 6th century BCE in southern Gaul, viticulture extended after the Roman conquest as far as the south of England. This paper presents different types of multi-proxy spatial modeling incorporating climatic, environmental and geohistorical factors to analyze the causes of the expansion of vineyards outside the Mediterranean reg...

Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature rec...

Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature rec...

The different components of the Mediterranean Basin (land, coast, and sea) are undergoing significant changes due to multiple anthropogenic pressures, including climate change, pollution and other factors. The 1st Mediterranean Assessment Report (MAR1), produced by the Mediterranean Experts on Climate and environmental Change (MedECC) and based on...

The variability and evolution of the physical parameters of atmospheric circulation are currently monitored in real time and on a global scale thanks to a dense network of weather stations and to satellite observations of the Earth. But the time span of these observations is relatively short as compared to the time characteristics of the processes...

Dendrochronology makes use of the annual pattern of tree radial growth in temperate regions. Each year trees put on a new ring under the bark whose width varies depending on various factors among which climate. Under same climatic conditions, trees of the same species growing at the same time show similar tree-ring patterns. Then there is agreement...

Pollen grains emitted by terrestrial plants are used as indicators of past vegetation and climate. They have a very resistant envelop which protects them from oxidation. The morphology of their envelop is a characteristic of the emitting plant type. Every year, terrestrial vegetation disperses billions of pollen grains which accumulate everywhere a...

In many parts of the world, the strong seasonality in the annual distribution of temperatures and rainfall is reflected in the annual growth of trees. It induces succession of clear and dark bands which record variations of the environment in which the trees have grown. It is the domain of dendrochronology, a discipline one century old only, which...

Virtually all sub-regions of the Mediterranean Basin, on land and in the sea, are impacted by recent anthropogenic changes in the environment. The main drivers of change include climate (temperature, precipitation, atmospheric circulation, extreme events, sea-level rise, sea water temperature, salinity and acidification), population increase, pollu...

Virtually all sub-regions of the Mediterranean Basin, on land and in the sea, are impacted by recent anthropogenic changes in the environment. The main drivers of change include climate (temperature, precipitation, atmospheric circulation, extreme events, sea-level rise, sea water temperature, salinity and acidification), population increase, pollu...

Fossil pollen records are well-established indicators of past vegetation changes. The prevalence of pollen across environmental settings including lakes, wetlands, and marine sediments, has made palynology one of the most ubiquitous and valuable tools for studying past environmental and climatic change globally for decades. A complementary research...

Food security and water security in the Mediterranean are intrinsically linked and are facing similar challenges. Food security is threatened mainly by the high dependency of Mediterranean countries on food imports, making them vulnerable to external pressures such as volatile food prices. From a nutritional standpoint, the number of overweight and...

Tree-ring archives are one of the main sources of information to reconstruct climate variations over the last millennium with annual resolution. The links between tree-ring proxies and climate have usually been estimated using statistical approaches, assuming linear and stationary relationships. Both assumptions may be inadequate, but this issue ca...

Abstract. Tree-ring archives are one of the main sources of information to reconstruct climate variations over the last millennium with annual resolution. The links between tree-ring proxies and climate have usually been estimated using statistical approaches, assuming linear and stationary relationships. Both assumptions may be inadequate but this...

Holocene climate variability in the Mediterranean Basin is often cited as a potential driver of societal change, but the mechanisms of this putative influence are generally little explored. In this paper we integrate two tools–agro-ecosystem modeling of potential agricultural yields and spatial analysis of archaeological settlement pattern data–in...

Locations of sites with regard to elevation and slope. (JPG)

References for SI. (DOCX)

Holocene temperature and precipitation in the study area averaged across cultural periods. (JPG)

Cultural history of provence. (DOCX)

Managing uncertainties. (DOCX)

Potential pulse productivity of the landscape. (JPG)

Summary W1 values for landscape and exploited fractions. (DOCX)

Comparisons of the W1 means of the exploited fractions for each period to the contemporary landscape (landscape mean of pixelwise means across the period for each pixel), and of each period to every other period. (PDF)

Full- text available through the IPCC website: https://www.ipcc.ch/sr15/

Recent accelerated climate change has exacerbated existing environmental problems in the Mediterranean Basin that are caused by the combination of changes in land use, increasing pollution and declining biodiversity. For five broad and interconnected impact domains (water, ecosystems, food, health and security), current change and future scenarios...

The 4.2 ka BP event is defined as a phase of environmental stress characterized by severe and prolonged drought of global extent. The event is recorded from the North Atlantic through Europe to Asia and has led scientists to evoke a 300-year global mega-drought. For the Mediterranean and the Near East, this abrupt climate episode radically altered...

The 4.2ka BP event is defined as a phase of environmental stress characterized by severe and prolonged drought of global extent. The event is recorded from the North Atlantic through Europe to Asia, leading scientists to evoke a 300-yr global mega-drought. Focusing on the Mediterranean and the Near East, this abrupt climate episode radically altere...

Assessing the implications of paleoclimatic and paleoenvironmental data at temporal and spatial scales that would have directly intersected with human decision-making and activity is a fundamental archaeological challenge. This paper addresses this challenge by presenting a spatial and temporal downscaling method that can provide quantitative high-...

The Tambora eruption (1815 AD) was one of the major eruptions of the last two millennia and has no equivalents over the last two centuries. Here, we collected an extensive network of early meteorological time series, climate simulation data and numerous, well-replicated proxy records from Eastern Canada to analyze the strength and the persistence o...

This paper explores the relationship between past climate and prehistoric Mediterranean agriculture by adapting a process-based dynamic vegetation model to estimate potential agricultural productivity under climate scenarios that characterize the extremes of Mediterranean climate in the Holocene. We adapt LPJmL (the Lund-Potsdam-Jena-managed-land m...

Northeastern North America has very few millennium-long, high-resolution climate proxy records. However, very recently, a new tree-ring dataset suitable for temperature reconstructions over the last millennium was developed in the northern Quebec taiga. This dataset is composed of one δ18O and six ring width chronologies. Until now, these chronolog...

Oxygen isotopes in tree rings (δ18OTR) are widely used to reconstruct past climates. However, the complexity of climatic and biological processes controlling isotopic fractionation is not yet fully understood. Here, we use the MAIDENiso model to decipher the variability in δ18OTR of two temperature-sensitive species of relevant palaeoclimatological...

A better understanding of the coupling between photosynthesis and carbon allocation in the boreal forest, together with its associated environmental factors and mechanistic rules, is crucial to accurately predict boreal forest carbon stocks and fluxes, which are significant components of the global carbon budget. Here, we adapted the MAIDEN ecophys...

Oxygen isotopes in tree-rings (δ18OTR) are widely used to reconstruct past climates. However, the complexity of climatic and biological processes controlling isotopic fractionation is not yet fully understood. Here, we use the MAIDENiso model to decipher the variability of δ18OTR of two temperature-sensitive species of relevant paleoclimatological...

Forest performance is challenged by climate change but higher atmospheric [CO2 ] (ca ) could help trees mitigate the negative effect of enhanced water stress. Forest projections using data-assimilation with mechanistic models are a valuable tool to assess forest performance. Firstly, we used dendrochronological data from 12 Mediterranean tree speci...

A better understanding of the coupling between photosynthesis and carbon allocation in the boreal forest, with implicated environmental factors and mechanistic rules, is crucial to accurately predict boreal forest carbon stocks and fluxes, which are significant components of the global carbon budget. Here we adapted the MAIDEN ecophysiological fore...

Oil, which sparked the first Gulf War, is not the only liquid resource that may trigger global crises from within a Middle Eastern theater. Water - or the lack of it - could be a cause of future conflicts because it is the most precious natural resource that can be manipulated and controlled by humans. Here, we report the written evidence for the d...

The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional size of the event, which had both an eruption magnitude and a volcanic explosivity i...

The meteorological observational period in Turkey, which starts ca. 1930 CE, is too short for understanding long-term climatic variability. Tree rings have been used intensively as proxy records to understand summer precipitation history of the region, primarily because they have a dominant precipitation signal. Yet, the historical context of tempe...

Après un rapide tour d’horizon de l’apport du GIEC à la problématique du changement climatique, cet article présente les contraintes liées à la volonté des négociateurs de l’Accord de Paris de limiter le réchauffement planétaire à moins de 2° C et même 1,5° C. Partant du constat que le réchauffement actuel a déjà atteint le seuil de + 1° C, on prés...

A warming limit for the Mediterranean basin Pollen cores from sediments provide rich detail on the history of vegetation and climate in the Mediterranean during the Holocene (the most recent ~10,000 years). Guiot and Cramer used this information as a baseline against which to compare predictions of future climate and vegetation under different clim...

We present a multiproxy record from magnetic susceptibility, loss on ignition and chemical analysis of a sediment core collected from “Ciénega Las Taunas”, a peatland in the northwest of the Sierra Madre Occidental in Mexico. The oldest sediments were dated to 12,850 cal yr BP. The relatively cool and wet Younger Dryas (YD) shows higher concentrati...

The last glacial-interglacial transition encompassed rapid climate oscillations that affected both hemispheres. At low latitudes, the pattern of oscillations is not well established. To address this issue, pollen analysis was performed at Ciénega San Marcial, a monsoon-influenced site located on the southeastern edge of the Sonoran Desert at the li...

Ce cahier thématique a été réalisé par le Groupe régional d’experts sur le climat en Provence-Alpes-Côte d’Azur (GREC-PACA). Il a été coordonné par l’association A.I.R. Climat (Philippe ROSSELLO) qui a pour mission d’animer le GREC-PACA. Le projet bénéficie d’un financement au titre de la Convention Etat - Région Provence-Alpes-Côte d’Azur - ADEME.

The 20th century was marked by significant decreases in spring temperature ranges and increased nighttime temperatures throughout Turkey. The meteorological observational period in Turkey, which starts ca. 1929 CE, is too short for understanding long-term climatic variability. Hence, the historical context of this gradual warming trend in spring te...

This paper explores the relationship between past climate and prehistoric Mediterranean agriculture by adapting a process-based dynamic vegetation model to estimate past agricultural productivity under climate scenarios that characterize the extremes of Mediterranean climate (warm/wet, cool/wet, warm/dry, and cool/dry) in the Holocene. We adapt LP...

The spatial context is critical when assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. Th...