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Over the past centuries, coastal marsh areas have been declining, mostly as a consequence of human impacts, including direct wetland conversion and land reclamation. More recently, accelerated global sea-level rise poses an additional challenge for the longevity of existing coastal marshes. This risk is further compounded by densely populated coastal zones, where coastal infrastructure inhibits the capacity of coastal marshes to migrate inland in response to rising sea levels (coastal squeeze). In the Mediterranean, coastal wetlands, incl. saltmarshes, are important contributors to the region’s high biodiversity, and provide a set of invaluable ecosystem services. Here, we present a study on the modelling of the future development of Mediterranean coastal marshes, taking into account both their ability to vertically adjust to increasing sea levels through sediment accumulation and their capacity to migrate inland in response to rising sea levels where sufficient inland migration space is available. In contrast to previous global studies, our preliminary results indicate an overall loss of coastal marshes by 2100 for all climate and management scenarios, even under low sea-level rise scenarios and when abundant inland migration space is available. Total losses are projected between 17% and 94% for RCP 2.6 with maximum available space for inland space; and RCP 8.5 with minimum space, respectively. A total loss of coastal marshes is projected for some Mediterranean countries by 2100. Nevertheless, the implementation of coastal management strategies facilitating the inland migration of coastal marshes as well restoration of catchment-to-coast sediment connectivity and enhancement of sediment trapping capacities can, to some degree, mitigate future coastal marsh losses.

Der erste, vom 2015 gegründeten unabhängigen Netzwerk von Mittelmeer-Experten für Klima- und Umweltveränderungen (MedECC) erstellte Bewertungsbericht für den Mittelmeerraum (MAR1), wurde im November 2020 veröffentlicht. MAR1 bewertet die besten wissenschaftlichen Erkenntnisse über Klima- und Umweltveränderungen und die damit verbundenen Risiken im Mittelmeerraum, um sie politischen Entscheidungsträgern, Stakeholdern und Bürgern zugänglich zu machen. Der Bericht enthält eine Zusammenfassung für politische Entscheidungsträger (Summary for Policymakers, SPM), die die Kernaussagen des MAR1 zusammenfasst, der ursprünglich in englischer Sprache und hier in der deutschen Fassung veröffentlicht wurde. 190 Wissenschaftler aus 25 Ländern haben den Bericht verfasst, alle haben ihren Beitrag in ihrer Eigenschaft als Einzelpersonen und ohne finanzielle Vergütung geleistet. Das UNEP/MAP - Sekretariat des Übereinkommens von Barcelona arbeitet über sein Regionales Aktivitätszentrum Plan Bleu und das Sekretariat der Union für das Mittelmeer partnerschaftlich zusammen, um MedECC zu unterstützen und zur Schaffung eines soliden und transparenten wissenschaftlichen Bewertungsprozesses beizutragen., Preferred citation: Zitierweise für dieses Dokument: MedECC – Zusammenfassung für politische Entscheidungsträger 2020 In: Klima- und Umweltveränderungen im Mittelmeerbecken – Aktuelle Situation und Risiken für die Zukunft (Climate and Environmental Change in the Mediterranean Basin – Current Situation and Risks for the Future). Erster Sachstandsbericht für den Mittelmeerraum [Cramer W., Guiot J., Marini K. (Hrsg.)] Union for the Mediterranean, Plan Bleu, UNEP/MAP, Marseille, Frankreich, S. 11-40, doi: 10.5281/zenodo.7081907

Il primo Rapporto di Valutazione del Mediterraneo (MAR1), preparato dalla rete indipendente di esperti mediterranei sui cambiamenti climatici e ambientali (MedECC) è stato pubblicato nel novembre 2020. MAR1 valuta le migliori conoscenze scientifiche sui cambiamenti climatici e ambientali e sui rischi associati nella regione del Mediterraneo, al fine di renderle disponibili ai responsabili politici, agli stakeholder e ai cittadini. Il rapporto comprende una Sintesi per i decisori politici (SPM) che coglie i messaggi chiave del MAR1, originariamente pubblicato in inglese e qui nella sua versione italiana. Il rapporto è stato redatto da 190 scienziati di 25 Paesi, che hanno contribuito individualmente e senza alcun compenso finanziario. L'UNEP/MAP - Segretariato della Convenzione di Barcellona, attraverso il suo Centro di attività regionale Plan Bleu, e il Segretariato dell'Unione per il Mediterraneo, lavoranno in partenariato per sostenere MedECC e contribuire alla creazione di un processo di valutazione scientifica solido e trasparente., Preferred Citation: Sintesi per i Decisori Politici come: Sintesi per i Decisori Politici. MedECC 2020 Summary for Policymakers. In: Climate and Environmental Change in the Mediterranean Basin - Current Situation and Risks for the Future. First Mediterranean Assessment Report [Cramer W, Guiot J, Marini K (ed.)] Unione per il Mediterraneo, Plan Bleu, UNEP/MAP, Marsiglia, Francia, pp 11-40, doi: 10.5281/zenodo.7515876.

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 climate and ecosystem models. The emulator connects the potential productivity of grapevines to global direct and indirect climate drivers, notably orbital parameters, solar and volcanic activities, demography, and greenhouse gas concentrations. This approach is particularly useful to place the evolution of future agrosystems in the context of their past variations. We found that variations in potential area for viticulture during the last 3 millennia in the Mediterranean Basin were mainly due to volcanic activity, while the effects of solar activity and orbital changes were negligible. In the future, as expected, the dominating factor is the increase in greenhouse gases, causing significantly drier conditions and thus major difficulties for viticulture in Spain and North Africa. These constraints will concern significant areas of the southern Mediterranean Basin when global warming exceeds +2 ∘C above preindustrial conditions. Our experiments showed that even intense volcanic activity comparable to that of the Samalas – sometimes considered to be the starting point of the Little Ice Age in the mid-13th century – would not decrease aridity and so not slow down this decline in viticulture extension in the southern margin of the Mediterranean area. This result does not confirm the idea of geoengineering that solar radiation modification (SRM) is an efficient option to limit future global warming.

In the Mediterranean region climate and other environmental changes have become major threats to both ecosystems and human wellbeing. Climate change is expected to be the most important threat to biodiversity in the Mediterranean over the next 10 years, followed by habitat degradation, exploitation, pollution, eutrophication and invasion of species and the loss of biodiversity. Climate change interacts with other environmental problems in the Mediterranean Basin, resulting from land use, pollution and biodiversity loss. The nature of the semi-enclosed Mediterranean Sea implies unique physiographic and ecological features. The Mediterranean Sea is considered as one of the hotspots of global biodiversity where the impact of climate change associated with other anthropogenic pressures could be the most destructive. Although it represents only 0.8% of the world's ocean surface, it is home to between 4 and 18% of the world's marine species.The Mediterranean region is particularly vulnerable because it cumulates environmental risks, including strong warming and drying, accelerating sea-level, rapid urbanization, increasing pollution of the air and the water, and the impacts of mass tourism. Ecosystems suffer from land degradation including the loss of half of the wetlands, overfishing (20% of fish species are at risk of extinction by 2050), non-sustainable agriculture, wildfires (burnt area may double by 2100) and the invasion of non-indigenous species (‘tropicalization’). These factors strongly impact water resources, biodiversity on land and in the ocean, human health and security.The effects of climate change in the Mediterranean basin are asymmetric. In the northern and western part of the Mediterranean, situation is heterogeneous, but historical responsibility of greenhouse emissions since industrial revolution is objectively higher than in southern and eastern part. The EU counties are facing impacts of climate change but societies are less vulnerable. Most countries located in the Southern and Eastern Mediterranean suffer the consequences of climate change with greater effects. Climate change can be an added challenge, when a country is already facing structural issues of poverty rate, weakness of infrastructure and social services, critical demographic changes, high unemployment, economic informality and emigration, political instability, corruption and spatial inequality with fast urbanization. All Mediterranean countries are nevertheless facing cross-cutting common issues, such as biodiversity preservation, sustainable development of tourism, commercial links related to food production and consumption, stock of fishes, blue carbon, energy production, political stability, migrations and security. Their interests are linked, because their share a common resource.The adaptive capacity of ecosystems and humans is expected to be progressively challenged due to the effects of droughts, heat waves, sea-level rise and ocean warming and acidification. Progress towards achievement of the UN Sustainable Development Goals differs strongly between Mediterranean sub-regions, with north-western countries having stronger resilience than southern and eastern countries.Our objective is to present the threats and vulnerabilities of the Mediterranean region. Then we will see the impacts on ecosystems, economic sectors and human well-being. Finally, we will present the different adaptation options, their limits and climate-resilient development pathways. Disclaimer : the content of IPCC reports are pre-decisional and confidential until they are formally accepted by member governments.

Climate and environmental changes as drivers of human migration likely reach back to the rise and decline of ancient civilizations in the Mediterranean Basin. At present, there is evidence of such changes and their impacts to cause risks for human security in the Mediterranean region particularly in its southern and eastern rim countries. Discussions on the relationships between climate change, conflicts, and human migration include framing these as potential threat multipliers, e.g., climate change-induced water shortages, which will lead to food insecurity and may thereby intensify conflicts and ultimately internal and cross-border migration. Most accounts anticipate these threat multipliers to occur in countries that are particularly vulnerable to climate change, lack adequate adaptive capacity, and be exposed to multiple socio-ecological stressors. Against the background of existing socio-political and armed conflicts in the Eastern and Southern Mediterranean, this risk deserves further scholarly attention. Inadequate or missing political instruments or agreements to deal with conflicts, insufficient cross-border collaboration, and limited links to international frameworks exacerbate the challenges faced by local communities in this region. These factors have likely contributed to the internal and cross-border migration of large groups of populations in war-torn countries in the Mediterranean Basin and elsewhere.Despite strong evidence for links between climate change and its consequences for water, food, and economic security, there is still significant debate as to the relative importance of them for individual decisions to migrate. Equally contested are propositions addressing a possible direct causal relationship between climate change impacts or climate variability and violent conflict. In addressing these issues, it quickly becomes clear that the relationships between climate and environmental changes, conflicts, and human migration are multi-causal and are characterized by complex interactions and feedbacks. Key determinants likely include the social, political, cultural, and economic conditions of a specific country or region as well as their historical trajectory.The Mediterranean Expert Group on Environmental and Climate Change (MedECC) has embarked on addressing these challenging issues through a Special Report that follows the First Mediterranean Assessment Report of MedECC (MAR1; 2019). Major issues to be addressed include:(i) how can we identify current “hot spots” of climate change impacts and ongoing or emerging conflicts;(ii) how can we shed light on understanding the roles of different determinants on internal and cross-border migration, particularly with regard to a) migration linked directly and/or indirectly to environmental change and conflicts, b) migration linked to other determinants, and c) understanding the relationships and interdependencies of different determinants;(iii) what are major knowledge gaps and what approaches should be followed to address them?While the “Task Force on Migration” of the Eastern Mediterranean and the Middle East - Cyprus Climate Change Initiative has already discussed strategies and policy instruments to enhance adaptation to climate change, the MedECC Special Report will refine and complete such assessment by considering the links between climate change, conflicts, and migration based on existing adaptation measures.This paper will provide background and rationale for the MedECC Special Report, its present state, and perspectives on its continued development.

The First Mediterranean Assessment Report (MAR1) prepared by the independent network of Mediterranean Experts on Climate and environmental Change (MedECC) is now published.MAR1 assesses the best available scientific knowledge on climate and environmental change and associated risks in the Mediterranean Basin in order to render it accessible to policymakers, stakeholders and citizens.The report includes a Summary for Policymakers (SPM), which comprises the key messages of the MAR1. The text of the SPM has been approved during a Plenary Session of MedECC Stakeholders on September 22, 2020. The report has been written by 190 scientists from 25 countries, all contributing in individual capacity and without financial compensation.The UNEP/MAP – Barcelona Convention Secretariat, through its Plan Bleu Regional Activity Center, and the Secretariat of the Union for the Mediterranean work in partnership to support MedECC, and to contribute to establish a sound and transparent scientific assessment process.

International audience; Global vegetation and land-surface models embody interdisciplinary scientific understanding of the behaviour of plants and ecosystems, and are indispensable to project the impacts of environmental change on vegetation and the interactions between vegetation and climate. However, systematic errors and persistently large differences among carbon and water cycle projections by different models highlight the limitations of current process formulations. In this review, focusing on core plant functions in the terrestrial carbon and water cycles, we show how unifying hypotheses derived from eco-evolutionary optimality (EEO) principles can provide novel, parameter-sparse representations of plant and vegetation processes. We present case studiesthat demonstrate how EEO generate parsimonious representations of core, leaf-level processes that are individually testable and supported by evidence. EEO approaches to photosynthesis and primary production, dark respiration, and stomatal behaviour are ripe for implementation in global models. EEO approaches to other important traits, including the leaf economics spectrum and applications of EEO at the community level are active research areas. Independently tested modules emerging from EEO studies could profitably be integrated into modelling frameworks that account for the multiple time scales on which plants and plant communities adjust toenvironmental change.

International audience; In the Mediterranean region, the long-term provision of agro-ecosystem services is threatened by accelerating climate change, unsustainable farming practices and other pressures. Alternative management practices such as conservation agriculture could be expected to ensure sustainability of ecosystem services from Mediterranean agro-ecosystems. Conservation agriculture is characterized by minimal soil disturbance, permanent soil cover, and diversification of crop species. We analyzed the impacts of several forms of alternative agricultural management practices (conservation tillage, cover cropping, mulching, manual weed management, organic fertilizer use, no-irrigation system) on multiple ecosystem services based on 155 published case studies (1994-2015). The effect size of various management options on four pro-visioning and four regulating ecosystem services were quantified. Impacts of conservation management options are not uniform. All regulating services were positively affected by the conservation management options except for the system without irrigation. In contrast, the provisioning services were inconsistently influenced by the conservation management options. For crop yield, environmentally sustainable soil management was beneficial, but organic fertilization (effect size =-0.17), manual weed management (effect size =-0.35) and no-irrigation system (effect size =-0.5) led to lower crop yields. The impact on crop biomass was mainly negative but not significant. Water availability was especially important to enhance both pro-visioning and regulating services. Overall, alternative agriculture management practices led to more positive than negative effects on ecosystem services in the study region. Stimulating the application of conservation management practices is therefore an important policy option for decision makers given the vulnerability of ecosystem services in the Mediterranean basin.

Worldwide, Mediterranean cropping systems face the complex challenge of producing enough high-quality food while preserving the quantity and quality of scarce water for people and agriculture in the context of climate change. While good management of nitrogen (N) is paramount to achieving this objective, the efficient strategies developed for temperate systems are often not adapted to the specificities of Mediterranean systems. In this work, we combine original data with a thorough literature review to highlight the most relevant drivers of N dynamics in these semi-arid systems. To do so, we provide an analysis at nested scales combining a bottom-up approach from the field scale, with a top-down approach considering the agro-food system where cropping systems are inserted. We analyze the structural changes in the agro-food systems affecting total N entering the territory, the contrasting response of yields to N availability under rainfed and irrigated conditions in a precipitation gradient, the interaction between N management and climate change adaptation, the main drivers affecting the release of Nr compounds (nitrate, ammonia, nitric oxide and nitrous oxide) compared with temperate systems and finally, the behavior of N once exported to highly regulated river networks. We conclude that sustainable N management in Mediterranean cropping systems requires the specific adaptation of practices to particular local agro-environmental characteristics with special emphasis on water availability for rainfed and irrigated systems. This approach should also include a systemic analysis of N input into the territory that is driven by the configuration of the agro-food system., This work was partly supported by 7th Framework Programmes funded by the European Union through the LUC4C project (Grant Agreement 603542). A Bondeau and W Cramer acknowledge Labex OTMed (ANR-11-LABX-0061) funded by the French Government Investissements d’Avenir program of the French National Research Agency (ANR) through the A∗MIDEX project (ANR-11-IDEX-0001-02). The authors are grateful to the Spanish Ministry of Economy and Competitiveness (AgroSceNA-UP, PID2019-107972RB-I00), the Comunidad de Madrid, Spain (AGRISOST-CM S2018/BAA-4330 pro ject). L Lassaletta is supported by Spanish Ministry of Economy and Competitiveness (MINECO) and European Commission ERDF Ramón y Cajal grant (RYC-2016-20269), Programa Propio from UPM and acknowledges the Comunidad de Madrid (Spain) and structural funds 2014-2020 (ERDF and ESF). Lassaletta is extremely grateful to Rafael Lassaletta (Nano) for permanent support and care. E Aguilera is supported by a Juan de la Cierva research contract from the Spanish Ministry of Economy and Competitiveness (FJCI-2017-34077). A Sanz-Cobena grate fully acknowledges the Autonomous Community of Madrid and UPM for their economic support through the research project APOYOJOVENES NFW8ZQ-42-XE8B5K.

International audience; 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, pollution, unsustainable land and sea use practices and non-indigenous species. In most areas, both natural ecosystems and human livelihoods are affected. Due to global and regional trends in the drivers, impacts will be exacerbated in the coming decades, especially if global warming exceeds 1.5 to 2°C above the pre-industrial level. Significantly enhanced efforts are needed in order to adapt to inevitable changes, mitigate change drivers and increase resilience.

International audience; Scenarios of biodiversity and ecosystem services (BES) are key for decision-makers to understand the consequences of future environmental change on BES. Though a major driver of terrestrial biodiversity loss, land use and land cover changes (LUCC) have been largely overlooked in previous BES assessments. But ecologists lack practical guidance for the general use of LUCC projections. We review the practices in use in LUCC-driven BES assessments and summarize the questions ecologists should address before using LUCC projections. LUCC-driven BES scenarios rely on a substantial set of different socioeconomic storylines (> 200 for 166 papers). Studies explore different futures, but generally concentrate on projections obtained from a single LUCC model. The rationale regarding time horizon, spatial resolution, or the set of storylines used is rarely made explicit. This huge heterogeneity and low transparency regarding the what, why, and how of using LUCC projections for the study of BES futures could discourage researchers from engaging in the design of such biodiversity scenarios. Our results call on those using LUCC projections to more systematically report on the choices they make when designing LUCC-based BES scenarios (e.g. time horizon, spatial and thematic resolutions, scope of contrasted futures). Beyond the improvement of reliability, reproducibility, and comparability of these scenarios, this could also greatly benefit others wanting to use the same LUCC projections, and help land use modellers better meet the needs of their intended audiences. The uncertainties in LUCC-driven BES futures should also be explored more comprehensively, including different socioeconomic storylines and different LUCC models, as recommended in studies dealing with climate-driven BES futures.

Most of the global population leaves in cities, expected to expand rapidly in the next decades. Cities and their industrial facilities are estimated to release more than 70% of fossil fuel CO2, although these estimates need to be verified at the city scale. Furthermore, cities are undergoing higher temperatures than their surrounding rural areas due to the Urban Heat Island (UHI) which also directly influence some CO2 fluxes (for example from buildings domestic heating, car air-conditioning, urban and rural vegetation uptake). Cities are thus strategic places where actions on mitigating CO2 emissions and also on lowering down atmospheric temperature elevation should be undertaken in priority.The ANR COoL-AMmetropolis project focuses on characterizing and mitigating CO2 emissions and UHI in the Aix-Marseille metropolis (AMm), of which the new governance entity is the “Metropole Aix-Marseille-Provence" (noted AMPM). AMm is the second most populated area of France (1.8 M inhabitants), is much industrialized, and is located in the PACA region strongly exposed to the risks of Climate Change. The objectives of the project are : (1) verifying and improving the spatio-temporal distribution of the AMm FFCO2 emissions estimates and quantifying their current contribution against natural fluxes, (2) characterizing the variability of the UHI and atmospheric CO2 at the diurnal, synoptic and seasonal scales in the AMm area, and modeling UHI and CO2 sources and sinks interactions at the local to the AMm scale; and (3) defining and evaluating the benefits of development scenarios of the AMm urban ecosystem to the horizon 2035 for mitigating both CO2 emissions and UHI, at the different scales, and find the most effective way to integrate the vertuous scenarios, defined in interaction with stakeholders, into legal and urban planning schemes, tools, charters or practices.To reach these objectives, a multidisciplinary Consortium made of 5 main partners (IMBE, CNRM, LIEU, AtmoSud, UMS Pytheas) and 6 non-funded partners (LSCE, INRA/URM, ESPACE, MIO, DTN, GNZ New-Zeeland) is proposed, ensuring complementarity between atmospheric physicists, urbanists, territorial jurists, emission stockcounters and AMm socio-economic actors with privileged links with local/regional stakeholders. Through its expertise and the organisation of annual seminars, GREC-SUD (sub-contract.) will reinforce these interactions.The project is organized in 4 workpackages. WP0 is dedicated to the project coordination. WP1 is assigned to the collection and analyzes of CO2 and UHI observations, and WP2 to the development and assessment of the CO2 and UHI modelling framework. WP1 and WP2 will feed WP3, dedicated to the role of the several levels in the AMPM in the governance for the urban adaptation strategies on the UHI and CO2 issues. It relies on legal documents analyses, multi-indicators evaluation of scenarios, and a strategy of ensuring regular interactions between the research community, local stakeholders & civil society throughout the full project duration.The ANR COoL-AMmetropolis is funded for 4 years, starting on January 2020.

Plants and vegetation play a critical-but largely unpredictable-role in global environmental changes due to the multitude of contributing processes at widely different spatial and temporal scales. In this Perspective, we explore approaches to master this complexity and improve our ability to predict vegetation dynamics by explicitly taking account of principles that constrain plant and ecosystem behaviour: natural selection, self-organization and entropy maximization. These ideas are increasingly being used in vegetation models, but we argue that their full potential has yet to be realized. We demonstrate the power of natural selection-based optimality principles to predict photosynthetic and carbon allocation responses to multiple environmental drivers, as well as how individual plasticity leads to the predictable self-organization of forest canopies. We show how models of natural selection acting on a few key traits can generate realistic plant communities and how entropy maximization can identify the most probable outcomes of community dynamics in space- and time-varying environments. Finally, we present a roadmap indicating how these principles could be combined in a new generation of models with stronger theoretical foundations and an improved capacity to predict complex vegetation responses to environmental change.Integrating natural selection and other organizing principles into next-generation vegetation models could render them more theoretically sound and useful for earth system applications and modelling climate impacts.

International audience; The Mediterranean region faces significant challenges to supply its growing population with food and living space. The region's potential to do so in the future is even more uncertain in the light of global change effects. Climate change will impact water availability in the region, which is already limited and often used at un-sustainable rates. To investigate the effects of global change and explore alternative development pathways of Mediterranean land use, we simulated two future scenarios with different land, water and biodiversity management transitions. We adopted a land systems approach, where land use and land cover are combined with data on land management, irrigation and livestock density, taking into account the characteristics of Mediterranean multifunctional landscapes, specific agricultural products, such as permanent crops, and irrigation water demands. Future land system changes were explored using the CLUMondo model for different development pathways of the region. We constrained the withdrawal of irrigation water based on existing freshwater resources. In a 'growth' scenario, we simulated a hypothetical future without consideration of environmental constraints and where food production and urban expansion are main priorities. The 'sustain-ability' scenario represents a future where limited water resources are extracted in a sustainable way and where areas of high biodiversity value are protected. The growth scenario projected significant intensification of land management, and loss of agro-silvo-pastoral mosaic systems. To achieve this, we calculate that the region would need to increase water withdrawal for irrigation significantly, resulting in increased pressure on freshwater resources. The sustainability scenario presents a way of increasing food production and at the same time improving the state of water resources, wetlands and traditional landscapes. Achieving this future would require improvements of yields of rain-fed systems and efficiencies of irrigated systems. The results indicate that coordinated environmental policy together with appropriate market access are needed to steer the regions land management towards a more sustainable future while ensuring food production.

International audience

P. 529–542 Land abandonment and the loss of traditional farming practices are thought to control land cover dynamics, and hence the ecosystem service supply in traditionally managed mountain landscapes. We evaluate the impact of land cover changes in Cantabrian Mountains (NW Spain), over 1990–2012, on the potential supply capacity of ecosystem services (regulating, provisioning, and cultural) at both regional and local scales. We also analyze trends in the use of ecosystem services at the local scale. Land cover changes were estimated from CORINE Land Cover database. Patterns of potential ecosystem service supply were assessed by applying an ecosystem service supply capacity matrix and trends in their actual use by using field data. Main trajectories of land cover change encompassed woody vegetation spread in semi-natural open systems and agricultural expansion in the most suitable areas. The capacity of landscape to provide ecosystem services improved during 1990–2012 at both scales. We detected trade-offs between the potential supply of ecosystem services associated to natural systems and those linked to traditional land uses, at both regional and local scales. Changes in the potential supply of ecosystem services matched trends in ecosystem service use. This study could help develop future scenarios to address upcoming challenges in ecosystem service supply SI

Attribution involves comparison of observed changes in the variable of interest with expected changes due to external forcings and drivers. Atmospheric warming currently occurs at different spatial scales, including globally. It is unabated and unequivocal. Climate change attribution statements play a very important role in the assessments of the Intergovernmental Panel on Climate Change. Attribution of climate change is an effort to scientifically explain the cause of changes observed recently in the Earth’s climate. Attribution studies to date have focused overwhelmingly on large-scale temperature changes, with continental and regional scale being of increasing interest. The growing emissions of greenhouse gases and the on-going change of the land surface affect, through the changing climate, many natural systems and almost every aspect of human life on Earth. There is considerable and understandable interest in detection and attribution of changes. Policy makers and the wider public want to know the detail of observed climate change and to understand why it happens.

Cramer, Wolfgang ... et al.-- 9 pages, 3 figures, 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 consistently point to significant and increasing risks during the coming decades. Policies for the sustainable development of Mediterranean countries need to mitigate these risks and consider adaptation options, but currently lack adequate information — particularly for the most vulnerable southern Mediterranean societies, where fewer systematic observations schemes and impact models are based. A dedicated effort to synthesize existing scientific knowledge across disciplines is underway and aims to provide a better understanding of the combined risks posed, Coordination was supported by the Laboratory of Excellence OT-Med (A*MIdex project no. 11-IDEX-0001-02)

Unidad de excelencia María de Maeztu MdM-2015-0552 Urbanization is an important driver of changes in land cover in the Mediterranean Basin and it is likely to impact the supply and demand of ecosystem services (ES). The most significant land cover changes occur in the peri-urban zone, but little is known about how these changes affect the ES supply. For eight European and four North African cities, we have quantified changes in peri-urban land cover, for periods of sixteen years (1990-2006) in the Northern African, and twenty-two years (1990-2012) in the European cities, respectively. Using an expert-based method, we derived quantitative estimates of the dynamics in the supply of twenty-seven ES. The nature of land cover changes slightly differed between European and North African Mediterranean cities, but overall it increased in urban areas and decreased in agricultural land. The capacity of the peri-urban areas of Mediterranean cities to supply ES generally reduced over the last 20-30 years. For nine ES the potential supply actually increased for all four North African cities and three out of the eight European cities. Across all cities, the ES timber, wood fuel and religious and spiritual experience increased. Given the expected increase of urban population in the Mediterranean Basin and the current knowledge of ES deficits in urban areas, the overall decrease in ES supply capacity of peri-urban areas is a risk for human well-being in the Mediterranean and poses a serious challenge for the Sustainable Development Goals in the Mediterranean basin.

International audience

International audience; A major challenge of current ecological research is to determine the responses of plant and animal communities and ecosystem processes to future environmental conditions. Ecosystems respond to climate change in complex ways, and the outcome may significantly depend on biodiversity. We studied the relative effects of enhanced drought and of plant species mixture on soil biota and on litter decomposition in a Mediterranean oak forest. We experimentally reduced precipitation, accounting for seasonal precipitation variability, and created a single-species litter (Quercus pubescens), a two-species litter mixture (Q. pubescens + Acer monspessulanum) and a three-species litter mixture (Q. pubescens + A. monspessulanum + Cotinus coggygria).In general, drier conditions affected decomposers negatively, directly by reducing fungal biomass and detritivorous mesofauna, and also indirectly by increasing the predation pressure on detritivorous mesofauna by predatory mesofauna. This is reflected under drier conditions in that Collembola abundance decreased more strongly than Acari abundance. One Collembola group (i.e. Neelipleona) even disappeared completely. Increased drought strongly decreased litter decomposition rates. Mixed litter with two and three plant species positively affected soil biota communities and led to a more efficient litter decomposition process, probably through a greater litter quality. Faster decomposition in mixed litter can thus compensate slower decomposition rates under drier condition. Synthesis. Our results highlight that, within our study system, drier climate strongly impacts on soil biodiversity and hence litter decomposition. Species-rich litter may mitigate such a decline in decomposition rates. Diverse plant communities should hence be maintained to reduce shifts in ecosystem functioning under climate change.

Bioclimatic indices for use in studies of ecosystem function, species distribution, and vegetation dynamics under changing climate scenarios depend on estimates of surface fluxes and other quantities, such as radiation, evapotranspiration and soil moisture, for which direct observations are sparse. These quantities can be derived indirectly from meteorological variables, such as air temperature, precipitation and cloudiness. Here we present a consolidated set of Simple Process-Led Algorithms for Simulating Habitats (SPLASH) allowing robust approximations of key quantities at ecologically relevant time scales. We specify equations, derivations, simplifications and assumptions for the estimation of daily and monthly quantities of top-of-the-atmosphere solar radiation, net surface radiation, photosynthetic photon flux density, evapotranspiration (potential, equilibrium and actual), condensation, soil moisture, and runoff, based on analysis of their relationship to fundamental climatic drivers. SPLASH, as presented here, is designed for application at discrete locations; however, the same methodology can naturally be applied to spatial grids. The climatic drivers include a minimum of three meteorological inputs: precipitation, air temperature, and either fraction of bright sunshine hours or fractional cloud cover. Indices, such as the moisture index, the climatic water deficit, and the Priestley-Taylor coefficient, are also defined. The SPLASH code is transcribed in C++, FORTRAN, Python, and R. One year of results from a specific location are provided to exemplify the daily and monthly model outputs, following a two-year spin-up of soil moisture content.

International audience; Regional Environmental Change now enters its 17 th volume, having published 1161 papers in 75 issues through its existence, 209 of them in 2016 alone. As editors, we are quite proud about this. We also know just how much work this represents, first of all by the authors presenting their work to us, and then through the huge time investment and intellectual contribution made by subject editors, guest editors and reviewers. Much of this work is carried out in anonymity, and so authors have little opportunity to thank for the invaluable support of their work they are receiving through this process. But we know this work is appreciated! For the papers submitted during the period of Nov 1, 2015 to Oct 31, 2016, in total 387 reviewers provided advice, often in the form of detailed and constructive statements including specific remarks for parts of the manuscript. On behalf of the authors, we as editors wish to thank these colleagues, and also all other reviewers, for their hugely important contribution. From next year onwards we plan to give this work some recognition by listing the full list of reviewers in the last issue of any year. We are pleased to be able to work with a strong group of handling editors – also they contribute large amounts of their time to the common objective of producing publications of high academic quality and interdisciplinary standards. Three of them deserve to be mentioned specifically, since they are now stepping down from work for our journal, after many years of unfaltering support: Elena Bennett, Helmut Geist, and Will Steffen have each been handling many papers, engaged in discussions with reviewers, authors and chief editors, and generally sorted out numerous small and large problems before papers were published. We want to use this space to point out just how grateful we are for their support! Now, with the first issue of 2017, we have decided to reorganize the journal's crucial support structure, its Editorial Board. In the past, the board consisted of a large group of colleagues (64 at the time of writing) who had all supported us by a great number of reviews and other activities. From now on, we plan to make their contributions visible by listing all reviewers at the end of a given annual volume. The Editorial Board, from now, on, will be composed of only the active handling editors, a group that is growing in number and also in diversity across disciplines and countries of residence. It currently includes – but several more colleagues will join us in the near future. So we thank the old Editorial Board for its reviewing activities (which we hope will continue), and we welcome our new Editorial Board with whom we plan to engage also in terms of discussing more generic issues of journal development.

International audience; The mapping of ecosystem service supply has become quite common in ecosystem service assessment practice for terrestrial ecosystems, but land cover remains the most common indicator for ecosystems ability to deliver ecosystem services. For marine ecosystems, practice is even less advanced, with a clear deficit in spatially-explicit assessments of ecosystem service supply. This ``situation, which generates considerable uncertainty in the assessment of ecosystems' ability to support current and future human well-being, contrasts with increasing understanding of the role of terrestrial and marine biodiversity for ecosystem functioning and thereby for ecosystem services. This paper provides a synthesis of available approaches, models and tools, and data sources, that are able to better link ecosystem service mapping to current understanding of the role of ecosystem service providing organisms and land/seascape structure in ecosystem functioning. Based on a review of literature, models and associated geo-referenced metrics are classified according to the way in which land or marine use, ecological processes and especially biodiversity effects are represented. We distinguish five types of models: proxy-based, phenomenological, niche-based, trait-based and full-process. Examples from each model type are presented and data requirements considered. Our synthesis demonstrates that the current understanding of the role of biota in ecosystem services can effectively be incorporated into mapping approaches and opens avenues for further model development using hybrid approaches tailored to available resources. We end by discussing ways to resolve sources of uncertainty associated with model representation of biotic processes and with data availability. (C) 2016 Elsevier Ltd. All rights reserved.

International audience

International audience; Global sustainability policies, such as the Sustainable Development Goals (SDGs) or the Aichi Targets, aim to ensure sustainable development, including improved human well-being and the conservation of nature. Although not yet explicitly used to evaluate the progress towards sustainable development, the ecosystem service concept implies a direct link between biodiversity and human well-being. This study explores how and which ecosystem services are currently considered in the SDGs and the Aichi Targets. We also identify which information might be already available for monitoring the progress towards their goals by reviewing national ecosystem assessments. This allows the identification of the main knowledge gaps for monitoring progress towards these global sustainability targets. There is a wealth of information on all major ecosystem services categories which is directly relevant for the Aichi Targets and the SDGs. The top 25% most cited ecosystem services across both policy documents are: Natural heritage and diversity, Capture fisheries, Aquaculture, Water purification, Crops, Cultural heritage & diversity and Livestock. Most monitoring information recommended for the global sustainability goals, as well as in the information available from national assessments, is biased towards supply related aspects of ecosystem services flows. In contrast, there is much less information on social behaviour, use, demand and governance measures. Indicators are rarely available for all aspects of a specific ecosystem service. The national statistical bureaus currently in charge of providing observations for reporting on SDGs, could be well placed to address this bias, by integrating ecological observations with socio-economic statistics into socioecological indicators for ecosystem services flows. IPBES can potentially address the gaps identified in this paper by improving coverage of the different dimensions of ecosystem services flows.

International audience; The United Nations Framework Convention on Climate Change Paris Agreement of December 2015 aims to maintain the global average warming well below 2°C above the preindustrial level. In the Mediterranean basin, recent pollen-based reconstructions of climate and ecosystem variability over the past 10,000 years provide insights regarding the implications of warming thresholds for biodiversity and land-use potential. We compare scenarios of climate-driven future change in land ecosystems with reconstructed ecosystem dynamics during the past 10,000 years. Only a 1.5°C warming scenario permits ecosystems to remain within the Holocene variability. At or above 2°C of warming, climatic change will generate Mediterranean land ecosystem changes that are unmatched in the Holocene, a period characterized by recurring precipitation deficits rather than temperature anomalies.

© 2016 Macmillan Publishers Limited, part of Springer Nature. The Paris Climate Agreement is an important step for international climate policy, but the compensation for negative effects of climate change based on clear assignment of responsibilities remains highly debated. From both a policy and a science perspective, it is unclear how responsibilities should be defined and on what evidence base. We explore different normative principles of justice relevant to climate change impacts, and ask how different forms of causal evidence of impacts drawn from detection and attribution research could inform policy approaches in accordance with justice considerations. We reveal a procedural injustice based on the imbalance of observations and knowledge of impacts between developed and developing countries. This type of injustice needs to be considered in policy negotiations and decisions, and efforts strengthened to reduce it.

This chapter explores the main results from the sub-global Millennium Assessments that have been undertaken in the Mediterranean Basin, and analyses the relationships between the provision of ecosystem services and the effect of different drivers of change in different Mediterranean ecosystems. The Mediterranean Basin is located across the south of Europe and the north of Africa. The multifunctional landscapes of the Mediterranean provide many examples of social-ecological systems with a diversity of disturbance levels, where ecosystems with extensive disturbance and human management can reach a peak of species and ecosystem services diversity. The Millennium Ecosystem Assessment has inspired several 'sub-global' assessments in the Mediterranean Basin, namely the Spanish National Ecosystem Assessment and the Israel National Ecosystem Assessment. Agroecosystems are those ecosystems managed with the intention of producing, distributing and consuming food, fuel and fibre. Trade-offs between ecosystem services occur in agroecosystems. Mediterranean forests and scrublands are important ecological infrastructure for biodiversity and the delivery of ecosystem services to people.

International audience; Efficient management of biodiversity requires a forward-looking approach based on scenarios that explore biodiversity changes under future environmental conditions. A number of ecological models have been proposed over the last decades to develop these biodiversity scenarios. Novel modelling approaches with strong theoretical foundation now offer the possibility to integrate key ecological and evolutionary processes that shape species distribution and community structure. Although biodiversity is affected by multiple threats, most studies addressing the effects of future environmental changes on biodiversity focus on a single threat only. We examined the studies published during the last 25years that developed scenarios to predict future biodiversity changes based on climate, land-use and land-cover change projections. We found that biodiversity scenarios mostly focus on the future impacts of climate change and largely neglect changes in land use and land cover. The emphasis on climate change impacts has increased over time and has now reached a maximum. Yet, the direct destruction and degradation of habitats through land-use and land-cover changes are among the most significant and immediate threats to biodiversity. We argue that the current state of integration between ecological and land system sciences is leading to biased estimation of actual risks and therefore constrains the implementation of forward-looking policy responses to biodiversity decline. We suggest research directions at the crossroads between ecological and environmental sciences to face the challenge of developing interoperable and plausible projections of future environmental changes and to anticipate the full range of their potential impacts on biodiversity. An intergovernmental platform is needed to stimulate such collaborative research efforts and to emphasize the societal and political relevance of taking up this challenge.

Any regular interaction of land and river during flooding affects carbon pools within the terrestrial system, riverine carbon and carbon exported from the system. In the Amazon basin carbon fluxes are considerably influenced by annual flooding, during which terrigenous organic material is imported to the river. The Amazon basin therefore represents an excellent example of a tightly coupled terrestrial–riverine system. The processes of generation, conversion and transport of organic carbon in such a coupled terrigenous–riverine system strongly interact and are climate-sensitive, yet their functioning is rarely considered in Earth system models and their response to climate change is still largely unknown. To quantify regional and global carbon budgets and climate change effects on carbon pools and carbon fluxes, it is important to account for the coupling between the land, the river, the ocean and the atmosphere. We developed the RIVerine Carbon Model (RivCM), which is directly coupled to the well-established dynamic vegetation and hydrology model LPJmL, in order to account for this large-scale coupling. We evaluate RivCM with observational data and show that some of the values are reproduced quite well by the model, while we see large deviations for other variables. This is mainly caused by some simplifications we assumed. Our evaluation shows that it is possible to reproduce large-scale carbon transport across a river system but that this involves large uncertainties. Acknowledging these uncertainties, we estimate the potential changes in riverine carbon by applying RivCM for climate forcing from five climate models and three CO2 emission scenarios (Special Report on Emissions Scenarios, SRES). We find that climate change causes a doubling of riverine organic carbon in the southern and western basin while reducing it by 20 % in the eastern and northern parts. In contrast, the amount of riverine inorganic carbon shows a 2- to 3-fold increase in the entire basin, independent of the SRES scenario. The export of carbon to the atmosphere increases as well, with an average of about 30 %. In contrast, changes in future export of organic carbon to the Atlantic Ocean depend on the SRES scenario and are projected to either decrease by about 8.9 % (SRES A1B) or increase by about 9.1 % (SRES A2). Such changes in the terrigenous–riverine system could have local and regional impacts on the carbon budget of the whole Amazon basin and parts of the Atlantic Ocean. Changes in riverine carbon could lead to a shift in the riverine nutrient supply and pH, while changes in the exported carbon to the ocean lead to changes in the supply of organic material that acts as a food source in the Atlantic. On larger scales the increased outgassing of CO2 could turn the Amazon basin from a sink of carbon to a considerable source. Therefore, we propose that the coupling of terrestrial and riverine carbon budgets should be included in subsequent analysis of the future regional carbon budget.

Large-scale environmental assessments involve the participation of many scientific disciplines, even more so when repeated throughout the decades and be implemented in institutionalized context such as the IPCC and the IPBES. Although the purported function of these international organizations is to provide a working interface between science and the decision-making circles at international level, the "boundary work" concerns as much the coordination between scientific disciplines not used to work together and lacking a common language, as it defines the interactions between the world of politics and that of scientists. The development of common standards for scientific evidence and plausibility is crucial, both within and then between the natural and social sciences. The challenge is to produce statements of greater clarity than otherwise found in scientific publications for the use of policymakers, without compromising the established scientific standards. The institutional similarities between these two international organizations are deliberate and originate from the same willingness of the UN member states to retain some control over potentially far-reaching scientific assessments (see chap. 2 above). Institutional differences are largely a consequence of more than two decades of experience between the establishment of the IPCC and that of IPBES, and the creation of a more favourable political "climate" during this time: Today, many member states recognise more clearly the potential for valuable policy support provided by science-policy interfaces as compared to the 1980s. Likewise, lobbying groups from all kinds of political background sense the need to actively relate to the existing science-policy interface. The development of IPBES will hopefully benefit from the IPCC experience in both areas, interaction with policymakers and complex scientific coordination. Therefore, it is important to understand the nature of the IPCC and its limits and shortcomings, and also to understand the differences between the two institutions. The first section of this chapter reviews the social sciences literature devoted to the IPCC and its reports without endorsing all the opinions expressed, to reflect on the kinds of problems and challenges the IPBES will have to face. The second section, based on the personal experience of the second co-author, both in the IPCC and in the nascent IPBES, illustrates these problems and emphasises the specificities of the IPBES in its early stages. The ambiguities of the IPCC "model"