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Forests provide important ecosystem services (ESs), including climate change mitigation, local climate regulation, habitat for biodiversity, wood and non‐wood products, energy, and recreation. Simultaneously, forests are increasingly affected by climate change and need to be adapted to future environmental conditions. Current legislation, including the European Union (EU) Biodiversity Strategy, EU Forest Strategy, and national laws, aims to protect forest landscapes, enhance ESs, adapt forests to climate change, and leverage forest products for climate change mitigation and the bioeconomy. However, reconciling all these competing demands poses a tremendous task for policymakers, forest managers, conservation agencies, and other stakeholders, especially given the uncertainty associated with future climate impacts. Here, we used process‐based ecosystem modeling and robust multi‐criteria optimization to develop forest management portfolios that provide multiple ESs across a wide range of climate scenarios. We included constraints to strictly protect 10% of Europe's land area and to provide stable harvest levels under every climate scenario. The optimization showed only limited options to improve ES provision within these constraints. Consequently, management portfolios suffered from low diversity, which contradicts the goal of multi‐functionality and exposes regions to significant risk due to a lack of risk diversification. Additionally, certain regions, especially those in the north, would need to prioritize timber provision to compensate for reduced harvests elsewhere. This conflicts with EU LULUCF targets for increased forest carbon sinks in all member states and prevents an equal distribution of strictly protected areas, introducing a bias as to which forest ecosystems are more protected than others. Thus, coordinated strategies at the European level are imperative to address these challenges effectively. We suggest that the implementation of the EU Biodiversity Strategy, EU Forest Strategy, and targets for forest carbon sinks require complementary measures to alleviate the conflicting demands on forests. [ABSTRACT FROM AUTHOR]

Climate change mitigation necessitates increased investment in green sectors. This study proposes a methodology to predict green finance growth across various countries, aiming to encourage such investments. Our approach leverages time-series Conditional Generative Adversarial Networks (CT-GANs) for data augmentation and Nonlinear Autoregressive Neural Networks (NARNNs) for prediction. The green finance growth predicting model was applied to datasets collected from forty countries across five continents. The Augmented Dickey-Fuller (ADF) test confirmed the non-stationary nature of the data, supporting the use of Nonlinear Autoregressive Neural Networks (NARNNs). CT-GANs were then employed to augment the data for improved prediction accuracy. Results demonstrate the effectiveness of the proposed model. NARNNs trained with CT-GAN augmented data achieved superior performance across all regions, with R-squared (R2) values of 98.8%, 96.6%, and 99% for Europe, Asia, and other countries respectively. While the RMSE for Europe, Asia, and other countries are 1.26e+2, 2.16e+2, and 1.16e+2 respectively. Compared to a baseline NARNN model without augmentation, CT-GAN augmentation significantly improved both R2 and RMSE. The R2 values for the Europe, Asia, and other countries models are 96%, 73%, and 97.2%, respectively. The RMSE values for the Europe, Asia, and various countries models are 2.24e+2, 7e+2, and 2.07e+2, respectively. The Nonlinear Autoregressive Exogenous Neural Network (NARX-NN) exhibited significantly lower performance across Europe, Asia, and other countries with R2 values of 74%, 52%, and 86%, and RMSE values of 1.11e+2, 3.63e+2, and 1.8e+2, respectively. [ABSTRACT FROM AUTHOR]

The EU Biodiversity Strategy 2030 aims to better protect natural ecosystems with high biodiversity and climate change mitigation potential. To achieve this goal, it is crucial to identify forests worth protecting, such as those characterized by long continuity and old age. Here, we propose a robust approach that combines historical maps from the mid‐19th century with remote sensing data to identify areas that have been forested for over 150 years, aiming to reduce the need for detailed and time‐consuming field investigations in potential conservation areas. We tested this approach in a 20,000 km2 region in the Polish Carpathians, an area likely containing many unprotected forests of high conservation value, where historical maps from the mid‐19th century are representative of much of Central Europe. Our results showed that an area of approximately 4200 km2 has been continuously forested since at least the mid‐19th century. Currently, 50% of these forests are outside protected areas, representing an important conservation opportunity. More generally, our approach can support the identification of valuable forests worth protecting before they are lost and provide useful insights for policymakers and stakeholders in the ongoing debate on the challenges of improving forest conservation in the Carpathians, and Europe more widely. [ABSTRACT FROM AUTHOR]

Although afforestation is a potential strategy to mitigate climate change by sequestering carbon, its potential biophysical effects on climate, such as regulating surface albedo, evapotranspiration, and energy balance, have not been fully incorporated into climate change mitigation strategies. This is partly due to the challenges associated with modeling the complex bidirectional interactions between vegetation and climate. In this study, we assess the impact of afforestation on low cloud cover using a regional climate model (RCM) and Earth observation data, applying a space‐for‐time approach to overcome limitations that may arise from comparing satellite and RCM results, such as different background climate conditions or different extents of land cover change. Our results show a consistent increase in low cloud cover in Europe due to afforestation in both datasets (3.71% and 3.56% on average, respectively), but the magnitude and direction of this effect depend on various factors, including location, seasonality, and forest type. These results suggest that afforestation can have important feedbacks on the climate system, and that its biophysical effects must be considered in climate change mitigation strategies. Furthermore, we emphasize the role of the modeling community in developing accurate and reliable approaches to assess the biophysical effects of land cover change on climate. Plain Language Summary: Although forests can help combat climate change by capturing carbon dioxide, we haven't fully considered the potential impact they can have on the climate in terms of biophysical factors such as surface reflectivity, evaporation, and energy balance. This is because it's challenging to accurately model the complex interactions between forests and climate. In this study, we used a regional climate model and Earth observation data to examine how forests affect the amount of low‐lying clouds. We used a method that compares satellite and model data to overcome limitations arising from different climate conditions and changes in land cover. Our findings consistently show that forests increase the coverage of low clouds in Europe. However, the specific effects depend on factors such as the location, season, and forest type. These results indicate that forests can have significant impacts on the climate system, and it is important to consider these effects when developing climate change strategies. We also emphasize the need for accurate modeling to better understand how changes in forest cover influence the climate. Key Points: Forests increase the amount of low clouds in EuropeForests impact climate beyond carbon sequestration [ABSTRACT FROM AUTHOR]

Climate change mitigation through negative CO2 emissions has been recognized as a crucial strategy to combat global warming. However, its potential effects on terrestrial productivity and agricultural activities remain uncertain. In this study, we utilized large ensemble simulations with an Earth system model of full complexity to investigate the response of Gross Primary Production (GPP) to CO2 forcings. Our findings reveal a significant asymmetry in the GPP response to CO2 ramp-up and symmetric ramp-down model experiments, especially in Europe, suggesting that GPP declines rapidly as CO2 levels decrease. Remarkably, during the CO2 removal period, the North Atlantic Sea surface temperature experienced cooling due to a delayed recovery of the Atlantic Meridional Overturning Circulation (AMOC). This cooling led to precipitation and soil moisture deficits, resulting in a rapid reduction in GPP. This asymmetry in GPP response holds consistent across multi-model simulations. These results underscore the potential implications of delayed recovery in ocean circulation, which could unexpectedly accelerate terrestrial GPP reduction. These insights are crucial for policymakers, aiding them in projecting agricultural activity and formulating targeted GPP control policies specific to the European region. [ABSTRACT FROM AUTHOR]

Soil management strategies involving the application of organic matter (OM) inputs (crop residues, green and livestock manure, slurry, digestate, compost and biochar) can increase soil carbon storage but simultaneously lead to an increase in non‐CO2 greenhouse gas (GHG) emissions such as N2O. Although multiple meta‐analyses have been conducted on the topic of OM input impacts on GHG, none has focused specifically on European arable soils. This study plugs this gap and can assist policymakers in steering European agriculture in a more sustainable direction. The objective of this meta‐analysis was to quantify how OM inputs of different nature and quality, but also the application strategy, can mitigate soil N2O emissions in different pedoclimatic conditions in Europe. We quantitatively synthesised the results of over 50 field experiments conducted in 15 European countries. Diverse arable crops, mainly cereals, were cultivated in monoculture or in crop rotations on mineral soils. Cumulative N2O emissions were monitored during periods of 30–1070 days in treatments, which received OM inputs, alone or in combination with mineral N fertiliser; and in controls fertilised with mineral N. The overall effect of OM inputs had a slight tendency to reduce N2O emissions by 10% (n = 53). With the increasing carbon‐to‐nitrogen ratio of the OM inputs, this mitigation effect became more pronounced. In particular, compost and biochar significantly reduced N2O emissions by 25% (n = 6) and 33% (n = 8) respectively. However, their effect strongly depended on pedoclimatic characteristics. Regarding the other types of OM inputs studied, a slight N2O emission reduction can be achieved by their application alone, without mineral N fertiliser (by 16%, n = 17). In contrast, their co‐application with mineral N fertiliser elevated emissions to some extent compared to the control (by 14%, n = 22). We conclude that amongst the seven OM inputs studied, the application of compost and biochar are the most promising soil management practices, clearly demonstrating N2O emission reduction compared to mineral N fertiliser. In contrast, other OM inputs had a small tendency to mitigate N2O emissions only when applied without mineral N fertiliser. [ABSTRACT FROM AUTHOR]

There is considerable academic interest in the potential for air quality improvement as a co-benefit of climate change mitigation. Few studies use regional air quality models for simulating future co-benefits, but many use global chemistry-climate model output. Using regional atmospheric chemistry could provide a better representation of air quality changes than global chemistry-climate models, especially by improving the representation of elevated urban concentrations. We use a detailed regional atmospheric chemistry model (WRF-Chem v 4.2) to model European air quality in 2050 compared to 2014 following three climate change mitigation scenarios. We represent different climate futures by using air pollutant emissions and chemical boundary conditions (from CESM2-WACCM output) for three Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0; a high, medium and low mitigation pathway). We find that in 2050, following SSP1-2.6, mean population-weighted PM2.5 concentrations across European countries reduces by 52 % compared to 2014. Whilst under SSP2-4.5, this average reduction is 34 %. The smallest average reduction was 18 % by following SSP3-7.0. Maximum 6-monthly-mean daily-maximum 8 h (6mDM8h) ozone (O3) is reduced across Europe by 15 % following SSP1-2.6, and 3 % following SSP2-4.5, but increases by 13 % following SSP3-7.0. This demonstrates clear co-benefits of climate mitigation. The additional resolution allows us to analyse regional differences and identify key sectors. We find that mitigation of agricultural emissions will be key for attaining meaningful co-benefits of mitigation policies, evidenced by the importance of changes in NO3 aerosol mass to determining future PM2.5 air quality and changes in CH4 emissions to future O3 air quality. [ABSTRACT FROM AUTHOR]

The voluntary-based initiative Covenant of Mayors (CoM) focused on the active role of local authorities and increased its targets by 2016, through the Sustainable Energy and Climate Action Plans (SECAPs) in terms of GHG reduction from 20% to 40% by 2030. In actual fact, the SECAP, intended as an urban planning tool, has the potential to improve the resilience of the EU Municipalities to climate-change, developing adaptation/mitigation actions and increasing the 'environmental awareness' of the involved actors. From a planning point of view, we affirm that the CoM started a new season of urban planning in Europe that covers the planning demand in the domain of implementing sustainable territorial development objectives. It unlocks the current ineffective planning systems and represents a remarkable practice promoting feasible framework projects for public and private investments. This paper proposes a methodological proposal to exploit this spread of SECAPs in the EU, including the systemic strategic planning approach in the process of SECAP design and ensuring an integrated vision of city development over the list of actions per sector required by the Global CoM procedures. Besides the methodological proposal, a review of the major EU energy policies is provided and relevant Best Practices are presented. [ABSTRACT FROM AUTHOR]

Natural forest expansion (NFE), that is, the establishment of secondary forest on non-forested land through natural succession, has substantially contributed to the widespread expansion of forests in Europe over the last few decades. So far, EU policies have largely neglected the potential of NFE for meeting policy objectives on restoration. Synthesising recent interdisciplinary research, this paper assesses the challenges and opportunities of NFE in view of contributing to European forest and ecosystem restoration. Specifically, we discuss the potential for supporting climate change mitigation and adaptation, biodiversity conservation, and forestry and economic use, summarize the current knowledge about societal perceptions and the policymaking on NFE, and make policy recommendations to better use the potential of NFE. We conclude that NFE has the potential to contribute to the European restoration policy agenda if local contexts and possible trade-offs are properly considered. [ABSTRACT FROM AUTHOR]

The timing of leaf senescence in deciduous trees influences carbon uptake and the resources available for tree growth, defense, and reproduction. Therefore, simulated biosphere‐atmosphere interactions and, eventually, estimates of the biospheric climate change mitigation potential are affected by the accuracy of process‐oriented leaf senescence models. However, current leaf senescence models are likely to suffer from a bias towards the mean (BTM). This may lead to overly flat trends, whereby errors would increase with increasing difference from the average timing of leaf senescence, ultimately distorting model performance and projected future shifts. However, such effects of the BTM on model performance and future shifts have rarely been investigated. We analyzed >17 × 106 past dates and >49 × 106 future shifts of leaf senescence simulated by 21 process‐oriented models that had been calibrated with >45,000 observations from Central Europe for three major European tree species. The surmised effects on model performance and future shifts occurred in all 21 models, revealing strong model‐specific BTM. In general, the models performed only slightly better than a null model that just simulates the average timing of leaf senescence. While standard comparisons of model performance favored models with stronger BTM, future shifts of leaf senescence were smaller when projected by models with weaker BTM. Overall, the future shifts for 2090–2099 relative to 1990–1999 increased by an average of 13–14 days after correcting for the BTM. In conclusion, the BTM substantially affects simulations by state‐of‐the‐art leaf senescence models, which compromises model comparisons and distorts projections of future shifts. Smaller shifts result from flatter trends associated with stronger BTM. Therefore, smaller shifts according to models with weaker BTM illustrate the considerable uncertainty in current leaf senescence projections. It is likely that state‐of‐the‐art projections of future biosphere behavior under global change are distorted by erroneous leaf senescence models. [ABSTRACT FROM AUTHOR]

Climate change mitigation in the tourism sector is expanding research areas due to the importance of this sector and its rapid expansion. Aviation's contribution was found to be the most important source of GHG emissions from tourism. Also, the hospitality sector contributes a lot to GHG emissions in tourism destinations. Hospitality, constituting an essential component of the tourism industry, is a sector that has a high potential to reduce GHG and use of energy and water resources. Therefore, it is important to monitor the climate change mitigation performance of tourism destinations to achieve decarbonization of the tourism sector. The main objectives of this paper are to develop indicators of climate change mitigation performance of tourism destinations based on GHG indicators for the transport and hospitality sectors and apply this framework to assessment and ranking based on climate change mitigation performance of 4 main EU geographical regions as tourism destinations: Central, Northern, Southern, and Western Europe. This paper's main methodological approach is comparing and ranking different geographical regions in the European Union by assessing their climate change mitigation performance as tourist destinations. The study's main results showed that Finland, representing North Europe, is the best-performing country in climate change mitigation in tourism destinations. The second-best-performing geographical region is Western Europe. The worst-performing EU region based on climate change mitigation in tourism destinations was Central Europe. The South Europe region was found to be in a slightly better position than Central Europe but worse in comparison with Western Europe and especially in comparison to Northern Europe. The study's main implications provide policy recommendations for Central Europe as a tourism destination to increase energy and water use efficiency and the carbon footprint of the tourism sector. [ABSTRACT FROM AUTHOR]

Decarbonising energy systems is a prevalent topic in the current literature on climate change mitigation, but the additional climate burden caused by methane emissions along the natural gas value chain is rarely discussed at the system level. Considering a two-basket greenhouse gas neutrality objective (both CO2 and methane), we model cost-optimal European energy transition pathways towards 2050. Our analysis shows that adoption of best available methane abatement technologies can entail an 80% reduction in methane leakage, limiting the additional environmental burden to 8% of direct CO2 emissions (vs. 35% today). We show that, while renewable energy sources are key drivers of climate neutrality, the role of natural gas strongly depends on actions to abate both associated CO2 and methane emissions. Moreover, clean hydrogen (produced mainly from renewables) can replace natural gas in a substantial proportion of its end-uses, satisfying nearly a quarter of final energy demand in a climate-neutral Europe. Cost-optimal European energy transition with CO2 and methane neutrality objective is studied. While renewables are the key drivers of climate neutrality, the continuous role of natural gas requires high levels of both CO2 and methane abatement. [ABSTRACT FROM AUTHOR]

The forthcoming energy transition driven by the need to reduce CO2 emissions requires large amounts of critical elements to construct renewable energy devices such as car batteries, wind turbines and solar panels. For many elements such as Li, Co, REEs and Ti, the production sources are located in countries with poor social and environmental standards, prone to political destabilization such as military conflicts, or vulnerable to strained relationships with consumer countries. Lately, the volatile geopolitical context has further demonstrated the high dependency of Europe and other developed countries in terms of raw material supply. In addition, there is a debate about the Earth's potential to sustain the transition toward a green society by using conventional resources from mining of terrestrial rocks. As nature conservation and climate mitigation are now priorities for the majority of governments, and since conventional mining on Earth suffers from a growing social resistance, humankind may need to look toward new frontier resources for supplying the mineral needs of the coming decades. Here, we explore the use of extra‐terrestrial resources as a potential source to feed the future supply of critical metals. Extra‐terrestrial mining may be an opportunity for wealth creation and an option for critical metal resource supply when mining on Earth becomes increasingly untenable. We conclude that the potential impacts of extraction and exploitation of space resources, both good and bad, could be societally profound. [ABSTRACT FROM AUTHOR]

Agricultural production plays an important role in the global economy, contributing greatly to the supply of food resources and human well-being. Mapping the areas of agricultural coverage and calculating their respective average annual production values is useful for orienting food security strategies, in a context of climate change and a growing global population. Despite their importance, today no complete and updated maps exist for all types of crops. To provide this critical data lack, we have harmonized statistical datasets at a regional level of detail across Europe (EU-27) to develop a unified dataset consisting of the best available data in the context of agricultural monitoring activities carried out by the CREA. This document illustrates the methodologies adopted to create an harmonized database and an open and easy-to-use cartographic atlas of agricultural area and production, based on accessible, interoperable and reusable data available from Eurostat. The availability of detailed maps of area and crop production at a regional level can help optimize a wide range of agricultural monitoring, ranging from early warning on phytopathological conditions, to assessment of crop conditions, to production forecasts and the assessment of damage caused by extreme weather events, agricultural statistics, agricultural insurance and climate mitigation and adaptation actions. [ABSTRACT FROM AUTHOR]

Today societies face an unprecedented challenge to limit global warming and restore agricultural soils. Recent studies show that the introduction of cover crops over Europe could result in a cooling impact due to an increase in soil organic carbon stocks, a decrease in the use of fertilizers, and an increase in surface albedo of the croplands. Based on the use of remote sensing data, land cover database, meteorological data, national agricultural statistics, and ground measurements, a generic model was developed to simulate the radiative forcing following the change in surface albedo. This article analyzes the impact of the introduction of cover crops in Europe during the fallow periods. Compared to previous studies, this work discusses: (i) The maximum greening potential in Europe and the associated indirect surface properties changes (ii) for snowfall episodes, and (iii) due to an increase in organic matter. This study shows that the mitigation potential of cover crops through albedo effects could reach 6.74 MtCO2-eq.yr−1 by extending the periods of the introduction of the cover crops to all possible fallow periods. This mitigation could be limited to 5.68 MtCO2-eq.yr−1 if the impact of snowfalls is considered. This would be equivalent to 9.12 gCO2.m−2.yr−1. Finally, this study investigates the feedback loop due to soil darkening with soil organic carbon content increase when cover crops are introduced, considering two scenarios. The first considers the soil organic carbon content increase following repeated incorporation of cover crop biomass into the soil, simulated with the DayCent model. The second, more conceptual and extreme scenario aims at alerting on the possible impact of a combination of carbon farming practices, such as biochar or organic amendments. Our results show that this effect could lead to a loss of 20% of the climate benefit (i.e., 5.39 MtCO2-eq.yr−1). In conclusion, this study shows that cover crops have a strong potential for climate mitigation through direct albedo effects (soil coverage). However, once introduced, cropland should be permanently covered by vegetation or straws in order to avoid this darkening feedback loop effect. [ABSTRACT FROM AUTHOR]

This article examines three constitutional environmental provisions and how they have been applied by courts in Europe in three climate cases from Norway, Germany and France. In each of these cases, directive principles, that is, constitutionally entrenched state obligations to protect social values, generally by enacting legislation, played a key role in judicial decisions regarding climate change mitigation. We engage with Lael K. Weis's analytical framework on directive principles to clarify the allocation of institutional responsibility for climate change mitigation as applied in these three cases, and argue that clarifying these roles alleviates some of the criticism regarding the democratic legitimacy of judicial decision making on climate change. Importantly, while courts do not directly enforce these types of constitutional directive principles, they must adjudicate them. When courts interpret constitutionally mandated legislation in light of directive principles, they develop new constitutional environmental norms. While most scholarly analysis of environmental constitutionalism has focused on environmental rights, our examination confirms Weis's thesis that directive principles aimed at legislatures are also important forms of environmental constitutionalism, and deserving of further attention. [ABSTRACT FROM AUTHOR]

Southeast Europe is considered one of the most vulnerable regions in the context of climate change, and projected future summer warming is expected to exceed global rates significantly. Despite the importance of this problem, there have been few studies that utilized Coupled Model Intercomparison Project Phase 5 (CMIP5) Global Circulation Models (GCMs) and the multi-model ensemble approach to examine extreme heat events on a regional scale. Additionally, the NEX-GDDP dataset, successfully applied in other parts of the world to assess extreme heat, has not yet been utilized for Southeast Europe. This study aims to fill that gap, presenting the time evolution and spatial distribution of extreme heat events in Southeast Europe for the historical period 1950–2005 and for the expected future climate up to the end of the 21st century based on the NEX-GDDP dataset. In order to leverage the strengths of the multi-model ensemble approach, a set of purpose-tailored indicators, such as the annual number of hot days, the maximum number of consecutive hot days, and hot spell duration at different thresholds, is computed by the daily maximum temperature data from all datasets, produced by NEX-GDDP (21 for the historical period and 42 for the future period). The E-OBS dataset is used as a reference for evaluating the NEX-GDDP's capability to simulate the features of the observed historical extreme heat events. The results show that the multi-model ensemble can satisfactorily capture the occurrence of extreme heat events in the historical period, and therefore it is reasonable to assume that the NEX-GDDP dataset has the potential to reproduce such extremes in the projected future. The study provides clear evidence that the persistence and spatial extent of extreme heat will increase significantly. Some indicators that were not relevant for the historical period due to the high-temperature threshold will become helpful in assessing extreme heat in Southeast Europe in the latter part of the century. Thus, under the RCP8.5 scenario, the area-averaged duration of hot spells at 32 °C and 34 °C will increase from near zero in 1976–2005 to 60 and 45 days, respectively, by the end of the century. The indicators used in the study may be helpful for decision-makers to implement climate change mitigation strategies and actions adequately. The findings are consistent with general tendencies in maximum temperatures considered in our previous works but also with the outcomes of recent studies dedicated to the future climate of the region. [ABSTRACT FROM AUTHOR]

Wetlands are a critical component of the landscape for climate mitigation, adaptation, biodiversity, and human health and prosperity. Keeping an eye on wetland vegetation is crucial due to it playing a major role in the planet's carbon cycle and ecosystem management. By measuring the chlorophyll fluorescence (ChF) emitted by plants, we can get a precise understanding of the current state and photosynthetic activity. In this study, we applied the Extreme Gradient Boost (XGBoost) algorithm to map ChF in the Biebrza Valley, which has a unique ecosystem in Europe for peatlands, as well as highly diversified flora and fauna. Our results revealed the advantages of using a set of classifiers derived from EO Sentinel-2 (S-2) satellite image mosaics to accurately map the spatio-temporal distribution of ChF in a terrestrial landscape. The validation proved that the XGBoost algorithm is quite accurate in estimating ChF with a good determination of 0.71 and least bias of 0.012. The precision of chlorophyll fluorescence measurements is reliant upon determining the optimal S-2 satellite overpass time, which is influenced by the developmental stage of the plants at various points during the growing season. Finally, the model performance results indicated that biophysical factors are characterized by greenness- and leaf-pigment-related spectral indices. However, utilizing vegetation indices based on extended periods of remote sensing data that better capture land phenology features can improve the accuracy of mapping chlorophyll fluorescence. [ABSTRACT FROM AUTHOR]

Large‐scale bioenergy plays a key role in climate change mitigation scenarios, but its efficacy is uncertain. This study aims to quantify that uncertainty by contrasting the results of three different types of models under the same mitigation scenario (RCP2.6‐SSP2), consistent with a 2°C temperature target. This analysis focuses on a single bioenergy feedstock, Miscanthus × giganteus, and contrasts projections for its yields and environmental effects from an integrated assessment model (IMAGE), a land surface and dynamic global vegetation model tailored to Miscanthus bioenergy (JULES) and a bioenergy crop model (MiscanFor). Under the present climate, JULES, IMAGE and MiscanFor capture the observed magnitude and variability in Miscanthus yields across Europe; yet in the tropics JULES and IMAGE predict high yields, whereas MiscanFor predicts widespread drought‐related diebacks. 2040–2049 projections show there is a rapid scale up of over 200 Mha bioenergy cropping area in the tropics. Resulting biomass yield ranges from 12 (MiscanFor) to 39 (JULES) Gt dry matter over that decade. Change in soil carbon ranges from +0.7 Pg C (MiscanFor) to −2.8 Pg C (JULES), depending on preceding land cover and soil carbon.2090–99 projections show large‐scale biomass energy with carbon capture and storage (BECCS) is projected in Europe. The models agree that <2°C global warming will increase yields in the higher latitudes, but drought stress in the Mediterranean region could produce low yields (MiscanFor), and significant losses of soil carbon (JULES and IMAGE). These results highlight the uncertainty in rapidly scaling‐up biomass energy supply, especially in dry tropical climates and in regions where future climate change could result in drier conditions. This has important policy implications—because prominently used scenarios to limit warming to 'well below 2°C' (including the one explored here) depend upon its effectiveness. [ABSTRACT FROM AUTHOR]

Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long‐term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground‐based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m3 of disturbed timber volume per year over the 70‐year study period. This value is likely a conservative estimate due to under‐reporting, especially of small‐scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m3/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long‐term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes. [ABSTRACT FROM AUTHOR]

The aviation industry is challenged to reduce its climate impact. The introduction of sustainable aviation fuels (SAF) is, among other policy instruments such as the European Emissions Trading Scheme, an option favored by policymakers in Europe to achieve this objective. These fuels feature substantially reduced carbon life-cycle emissions in comparison to fossil fuels. In Europe, a mandatory quota for the use of sustainable fuels will most likely be introduced, starting in the year 2025. The introduction of a blending mandate by governments and the European Commission is associated with a range of challenges. The purpose of this paper is to discuss the economics of climate change mitigation in aviation and the role SAFs can play. The economic issues associated with the introduction of SAFs are analyzed, with a particular focus on the European Commission's proposal for a blending mandate. Several suggestions for improvement are discussed. Furthermore, alternatives to SAFs are presented and evaluated. [ABSTRACT FROM AUTHOR]

Soil moisture is central to local climate on land. In situ soil moisture observations are vital for observing vegetation‐relevant root‐zone soil moisture. However, stations included in the International Soil Moisture Network are sparse in regions with strong land‐atmosphere coupling. We apply a machine‐learning‐based procedure for informing future station placement using virtual soil moisture stations in future CMIP6 projections. Stations are placed where the climate is currently most under‐represented. This strategy outperforms random station placement and station placement according to geographical distance. Doubling the current number of stations using this method alleviates the uneven global distribution of stations, increases the skill in the estimation of inter‐annual variability and trends in dry‐season soil moisture, and reduces its differences across climates in future projections. Stations are predominantly placed in tropical climates, especially when optimizing for drying trends. The results can inform future station placement to support climate change mitigation efforts. Plain Language Summary: Water stored in the ground as soil moisture is the main water supply for ecosystems and can influence local weather. Ground observations of soil moisture can measure water in deeper soil layers that roots can access. Many stations are collected in the International Soil Moisture Network database. However, this database mainly contains observation stations from the US and Europe. If we were to put additional stations, we should focus on regions and climates that the current network does not sufficiently cover. Locations in model projections of future climate that currently contain a station ("virtual stations") are used to build a machine‐learning model that predicts soil moisture at locations without stations. We then place new virtual stations where the prediction error of dry‐season soil moisture variability and dry‐season trends is largest. This strategy outperforms randomly placing new stations or placing stations where they are most distant from existing ones. Stations are placed predominantly in the tropics, but prediction improves in all regions. Furthermore, stations are more evenly distributed across the globe, and differences in skill between regions become smaller. This tool can be used to decide where to place future soil moisture stations, which are important for monitoring climate change. Key Points: In situ soil moisture observations are distributed unequally across the globe and sparse in regions with strong land‐atmosphere couplingWe present a machine‐learning based procedure for informing future station placement using virtual soil moisture stationsDoubling the number of stations with this strategy reduces error in soil moisture trends by 0.2–1.4 kg m−2 and reduces global differences [ABSTRACT FROM AUTHOR]

Integrating peatland restoration measures with climate policy is critical for meeting climate targets, but the current policies often fall short of utilizing the large potential that exists. Despite growing private sector interest, few regional voluntary carbon markets for peatlands have emerged worldwide. In this study, we explore three pioneering examples from Europe. From the perspective of social innovation, we aim to provide clarity on how these innovations emerged and developed, which actors drove the innovation process by assuming which roles, and which factors fostered or hindered the development. We do so by mapping the innovation process using Process Net-Map. The results show that all three cases have followed remarkably similar patterns in their innovation processes. Four phases, i.e. preparation, definition, refinement, and up-scaling were identified, as were actors' roles as innovators, promoters, intermediaries, implementers, and knowledge providers. However, the case studies are very different with regard to which actor constellation drove the innovation process: MoorFutures is driven by public and scientific actors, Valuta vor Veen is promoted by civil society actors in consultation with practitioners, and Hiilipörssi shifted from civil society to private actors. The governance modes, that is, actor constellation and their goals, have led to differences in concept, robustness of methodology, mitigation measure, and possibly potential for up-scaling. Our study indicates that the timing of interventions when actors with certain roles stepped in can accelerate the innovation process. Important political, economic, technical, and social factors influencing the innovation process, especially knowledge and trust accumulated between some key actors, are outlined. Private funding for regional voluntary carbon markets (VCMs) can tap the climate mitigation potential from peatlands, which is not currently adequately addressed by governments. Actor constellation drove the innovation process, leading to different concepts, methodologies, and mitigation measures. The timing of interventions by actors, notably providing seed funding, network, expertise and visibility, was critical for success. Building trust for regional VCMs requires not only a robust methodology to calculate emission reductions but also partnership and endorsement. The future development of climate policy on peatlands could be a decisive factor in regional VCMs. [ABSTRACT FROM AUTHOR]

The agriculture sector can contribute to climate change mitigation by reducing its own greenhouse gas (GHG) emissions, sequestering carbon in vegetation and soils, and providing biomass to substitute for fossil fuels and other GHG‐intensive products. The sector also needs to address water, soil, and biodiversity impacts caused by historic and current practices. Emerging EU policies create incentives for cultivation of perennial plants that provide biomass along with environmental benefits. One such option, common in northern Europe, is to include grass in rotations with annual crops to provide biomass while remediating soil organic carbon (SOC) losses and other environmental impacts. Here, we apply a spatially explicit model on >81,000 sub‐watersheds in EU27 + UK (Europe) to explore the effects of widespread deployment of such systems. Based on current accumulated SOC losses in individual sub‐watersheds, the model identifies and quantifies suitable areas for increased grass cultivation and corresponding biomass‐ and protein supply, SOC sequestration, and reductions in nitrogen emissions to water as well as wind and water erosion. The model also provides information about possible flood mitigation. The results indicate a substantial climate mitigation potential, with combined annual GHG savings from soil‐carbon sequestration and displacement of natural gas with biogas from grass‐based biorefineries, equivalent to 13%–48% of current GHG emissions from agriculture in Europe. The environmental co‐benefits are also notable, in some cases exceeding the estimated mitigation needs. Yield increases for annual crops in modified rotations mitigate the displacement effect of increasing grass cultivation. If the grass is used as feedstock in lieu of annual crops, the displacement effect can even be negative, that is, a reduced need for annual crop production elsewhere. Incentivizing widespread deployment will require supportive policy measures as well as new uses of grass biomass, for example, as feedstock for green biorefineries producing protein concentrate, biofuels, and other bio‐based products. [ABSTRACT FROM AUTHOR]

This document presents a comprehensive review of research works, regulatory frameworks, technical solutions, and commercial trends related to the integration of shallow geothermal energy (SGE) technologies in modern 5th-generation district heating and cooling (5GDHC) networks. This literature and market analysis is contextualized by the present geopolitical, environmental, and societal scenario in Europe. In this sense, decarbonization of the heating and cooling sector is a crucial piece in the energy transition puzzle to keep global warming below the critical threshold of 1.5 °C by the next century. Moreover, Ukraine war has added urgency to end up with fossil fuel dependency. The most relevant outcome of this literature review is the synergistic relationship between SGE, 5GDHC networks, and urban environments. SGE is most efficiently deployed in urban environments when it is part of a district heating and cooling network, and the modern concept of 5GDHC is the most suitable scenario for it. Since the potential contribution of SGE to the decarbonization of the heating and cooling supply is mostly untapped across Europe, this synergistic effect represents a possible boost. Hybridization with solar photovoltaics and/or storage makes it even more attractive. Outstanding cases are reviewed, challenges for the future are presented, and tools to overcome social reluctance and/or lack of awareness are described, along with a discussion of the stimuli for the deployment of SGE and 5GDHC networks. A particular focus on Mediterranean countries is presented, where SGE systems and DHC networks of any kind show a particularly low deployment compared to the rest of Europe. To this end, the second part of this work evaluates, justifies, and analyzes the possibilities and potentialities of their application in this zone. [ABSTRACT FROM AUTHOR]

Afforestation is an important mitigation strategy for climate change due to its carbon sequestration potential. Besides this favorable biogeochemical effect on global CO 2 concentrations, afforestation also affects the regional climate by changing the biogeophysical land surface characteristics. In this study, we investigate the effects of an idealized global CO 2 reduction to pre-industrial conditions by a Europe-wide afforestation experiment on the regional longwave radiation balance, starting in the year 1986 on a continent entirely covered with grassland. Results show that the impact of biogeophysical processes on the surface temperatures is much stronger than that of biogeochemical processes. Furthermore, biogeophysically induced changes of the surface temperatures, atmospheric temperatures, and moisture concentrations are as important for the regional longwave radiation balance as the global CO 2 reduction. While the outgoing longwave radiation is increased in winter, it is reduced in summer. In terms of annual total, a Europe-wide afforestation has a regional warming effect despite reduced CO 2 concentrations. Thus, even for an idealized reduction of the global CO 2 concentrations to pre-industrial levels, the European climate response to afforestation would still be dominated by its biogeophysical effects. [ABSTRACT FROM AUTHOR]

Afforestation is an important mitigation strategy to climate change due to its carbon sequestration potential. Besides this positive biogeochemical effect on global CO2 concentrations, afforestation also affects the regional climate by changing the biogeophysical land surface characteristics. In this study, we investigate the effects of an idealized global CO2 reduction to pre-industrial conditions by a Europe wide afforestation experiment on the regional longwave radiation balance, starting in the year 1986 from a continent entirely covered with grassland. Results show that the impact of biogeophysical processes on the surface temperatures is much stronger than of biogechemical processes. Furthermore, biogeophysically induced changes of the surface temperatures, atmospheric temperatures and moisture concentrations are as important for the regional greenhouse effect as the global CO2 reduction. While the greenhouse effect is strengthened in winter, it is weakened in summer. On annual total, a Europe-wide afforestation has a regional warming effect, despite reduced CO2 concentrations. Thus, even for an idealized reduction of the global CO2 concentrations to pre-industrial levels, the European climate response to afforestation would still be dominated by its biogeophysical effects. [ABSTRACT FROM AUTHOR]

Although cities have risen to prominence as climate actors, emissions' data scarcity has been the primary challenge to evaluating their performance. Here we develop a scalable, replicable machine learning approach for evaluating the mitigation performance for nearly all local administrative areas in Europe from 2001-2018. By combining publicly available, spatially explicit environmental and socio-economic data with self-reported emissions data from European cities, we predict annual carbon dioxide emissions to explore trends in city-scale mitigation performance. We find that European cities participating in transnational climate initiatives have likely decreased emissions since 2001, with slightly more than half likely to have achieved their 2020 emissions reduction target. Cities who report emissions data are more likely to have achieved greater reductions than those who fail to report any data. Despite its limitations, our model provides a replicable, scalable starting point for understanding city-level climate emissions mitigation performance. Since the Paris Agreement recognized in 2015 cities have pledged climate actions that often exceed the scope and ambition of their national governments' policies but there is scant evidence of these actions' outcomes, largely because of the lack of reported emissions data. Here the authors utilize spatially explicit datasets relevant to urban carbon emissions and self-reported emissions data from European cities, and develops a machine-learning approach to predict and explore trends in city-scale mitigation. [ABSTRACT FROM AUTHOR]

While the importance of permanent grasslands (PG) for the conservation of high nature value habitats is often acknowledged, their role in most of the main sustainable food system scenarios published in the last few years is less explicit. In the best case, the place of permanent grassland in scenarios and policy agendas is their conservation; in the worst one, they are simply replaced by afforested land or cropland, considered as a better option when the focus is on GHG emissions only. In this paper, we defend the idea that several misinterpretations of the positive and negative impacts of ruminants, the 'natural' users of PG, explain why ruminants are poorly addressed by most scenarios. Based on the findings of an agroecological scenario for Europe—TYFA, standing for Ten Years For Agroecology—in which extensive permanent grassland and ruminants together play a prominent role for biodiversity conservation, nitrogen cycling and climate change mitigation and adaptation, we call for a research agenda that would better inform the specific role of PG in the provision of ecosystem services—and in particular those that depend on nitrogen management. [ABSTRACT FROM AUTHOR]

How do welfare state policies affect the political support for environmental action of economically vulnerable social groups? Two competing hypotheses can be delineated. On the one hand, a synergy logic would imply that welfare state generosity is associated with higher support for environmental action among economically vulnerable groups due to the insecurity reducing effects of the welfare state. On the other hand, a crowding-out logic would suggest that welfare state generosity is associated with lower support for other policy priorities like environmental action. We test these two hypotheses using 2019 Eurobarometer survey data and country-level indicators of welfare state generosity in 22 European countries. We find that the working class and the elderly are particularly opposed to individual and national environmental action and that the welfare state plays a complex moderating role. Consistent with a synergy logic, welfare state generosity increases pro-environmental behaviour among the working class, but its association with more positive attitudes towards national environmental policies is less strong. Consistent with a crowding-out logic, the elderly appear less likely to behave in environmentally friendly ways if retirement benefits are high. To explore the mechanisms behind this association, we show that the working class who struggle to pay their bills are most opposed to environmental action. Overall, economic insecurities are key obstacles for support of environmental actions and the effects of the welfare state depend both on which social group is concerned and whether individual behaviour versus policy preferences are considered. [ABSTRACT FROM AUTHOR]

Forest models are instrumental for understanding and projecting the impact of climate change on forests. A considerable number of forest models have been developed in the last decades. However, few systematic and comprehensive model comparisons have been performed in Europe that combine an evaluation of modelled carbon and water fluxes and forest structure. We evaluate 13 widely used, state‐of‐the‐art, stand‐scale forest models against field measurements of forest structure and eddy‐covariance data of carbon and water fluxes over multiple decades across an environmental gradient at nine typical European forest stands. We test the models' performance in three dimensions: accuracy of local predictions (agreement of modelled and observed annual data), realism of environmental responses (agreement of modelled and observed responses of daily gross primary productivity to temperature, radiation and vapour pressure deficit) and general applicability (proportion of European tree species covered). We find that multiple models are available that excel according to our three dimensions of model performance. For the accuracy of local predictions, variables related to forest structure have lower random and systematic errors than annual carbon and water flux variables. Moreover, the multi‐model ensemble mean provided overall more realistic daily productivity responses to environmental drivers across all sites than any single individual model. The general applicability of the models is high, as almost all models are currently able to cover Europe's common tree species. We show that forest models complement each other in their response to environmental drivers and that there are several cases in which individual models outperform the model ensemble. Our framework provides a first step to capturing essential differences between forest models that go beyond the most commonly used accuracy of predictions. Overall, this study provides a point of reference for future model work aimed at predicting climate impacts and supporting climate mitigation and adaptation measures in forests. [ABSTRACT FROM AUTHOR]

Substantial amounts of money have been invested in peatland restoration over the last decades to address the current challenges of global changes and to enhance biodiversity. Given the magnitude of financial investments and the pressing societal needs, it is essential that appropriate decisions are made about the restoration techniques employed to avoid negative consequences and to optimise the benefits to human society.Based on the knowledge and expertise that has been developed over recent decades, three approaches to peatland restoration are discussed regarding their implications for climate change, nutrient fluxes and biodiversity: peatland inundation, topsoil removal and slow rewetting.Considered over the long term, for instance tens or hundreds of years, rewetted peatlands have the potential to fulfil multiple restoration goals, including those targeting climate change mitigation, water quality protection and species conservation. In short term, ill‐informed decisions on the approach to peatland restoration can generate negative impacts, for instance on the downstream water quality or radiative forcing gas emissions.Synthesis and application. The restoration of peatlands, and the trajectory that any restorative action may take, is a matter of societal choice; however, it is essential that society understands the broad potential benefits and disadvantages that such restoration may have so that evidence‐based choices can be made. [ABSTRACT FROM AUTHOR]

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Forests sequester atmospheric carbon dioxide (CO2) which is important for climate mitigation. Net ecosystem production (NEP) varies significantly across forests in different regions depending on the dominant tree species, stand age, and environmental factors. Therefore, it is important to evaluate forest NEP and its potential changes under climate change in different regions to inform forestry policy making. Norway spruce (Picea abies) is the most prevalent species in conifer forests throughout Europe. Here, we focused on Norway spruce forests and used eddy covariance-based observations of CO2 fluxes and other variables from eight sites to build a XGBoost machine learning model for NEP estimation. The NEP values from the study sites varied between −296 (source) and 1253 (sink) g C m−2 yr−1. Overall, among the tested variables, air temperature was the most important factor driving NEP variations, followed by global radiation and stand age, while precipitation had a very limited contribution to the model. The model was used to predict the NEP of mature Norway spruce forests in different regions within Europe. The NEP median value was 494 g C m−2 yr−1 across the study areas, with higher NEP values, up to >800 g C m−2 yr−1, in lower latitude regions. Under the "middle-of-the-road" SSP2-4.5 scenario, the NEP values tended to be greater in almost all the studied regions by 2060 with the estimated median of NEP changes in 2041–2060 to be +45 g C m−2 yr−1. Our results indicate that Norway spruce forests show high productivity in a wide area of Europe with potentially future NEP enhancement. However, due to the limitations of the data, the potential decrease in NEP induced by temperature increases beyond the photosynthesis optima and frequent ecosystem disturbances (e.g., drought, bark beetle infestation, etc.) still needs to be evaluated. [ABSTRACT FROM AUTHOR]

Electricity demand is a crucial factor in energy system planning. Understanding future electricity demand is vital for developing effective energy and climate policies, as well as establishing a resilient and sustainable energy system. In light of these considerations, the escalating challenges posed by climate change are anticipated to have a substantial impact on electricity demand. This study, therefore, provides a comprehensive analysis delving into the dynamic nature of Temperature Response Functions (TRFs) of electricity demand across Europe. By examining various factors influencing electricity demand in residential buildings, such as thermal insulation, heating electrification, space cooling, and passive cooling, we aim to understand their collective impact on shaping future Temperature Response Functions. To project electricity demand, our study incorporates these factors into our scenario assumptions. Through a comprehensive investigation of these scenarios, our findings reveal distinctive regional influences of these factors. In regions where heating demand prevails, an initial increase in electricity demand is anticipated due to increased electrification rates. However, improved building thermal insulation is expected to substantially reduce winter electricity demand in the long run. Conversely, in regions with pronounced cooling demand, a notable escalation in electricity demand is foreseen due to increased space cooling penetration rate. Nevertheless, the application of effective passive cooling measurements is expected to mitigate and markedly diminish this increase. By highlighting the differential influences of these factors on electricity demand across Europe, our findings can offer valuable insights and guidelines first for energy system modelers for considering the change in Temperature Response Functions and second for policymakers to develop effective climate change adaptation and mitigation strategies. • Examination of the dynamic characteristics of Temperature Response Functions (TRFs). • Space and passive cooling, electric heating, insulation effects on electricity demand. • Projection of TRFs and electricity demand for 36 European countries until 2100. • Thermal insulation and passive cooling are essential for reducing electricity demand. [ABSTRACT FROM AUTHOR]

This study investigates the potential of utilizing carbon credits to finance innovative local energy communities in Europe, addressing a significant gap in academic literature. Despite the growing interest in voluntary carbon credits as a mechanism for offsetting carbon emissions, there is limited evidence connecting local energy systems to voluntary carbon markets. The study explores whether carbon credits could serve as a practical tool for funding the development of energy communities, contributing to sustainable energy transitions and climate mitigation strategies. The research employs a comprehensive methodology to assess the quality of carbon credit projects and examines ten innovative energy community projects in Europe. Key findings reveal there is potential for using carbon credits to finance energy community initiatives. However, challenges persist, particularly regarding financing barriers and the volatile nature of carbon markets. The study underscores the importance of policy support in establishing clear standards for voluntary markets and promoting the accessibility of carbon offsets. Furthermore, it suggests potential solutions such as pre-financing agreements and the utilization of carbon market derivatives to enhance project viability. Overall, the study offers insights into the intersection between voluntary carbon markets and local energy initiatives, providing a foundation for further research and policy development in the field of local sustainable development and climate change mitigation. [Display omitted] • Innovative local energy communities in Europe have significant carbon emissions reduction potential. • Carbon credit issuance could financially support the development of local energy initiatives. • Challenges persist in accessing financing and navigating volatile carbon markets. • Policy support is crucial in establishing clear standards for voluntary carbon markets. [ABSTRACT FROM AUTHOR]

Recent climate change mitigation strategies rely on the reduction of methane (CH 4) emissions. Carbon and hydrogen isotope ratio (δ13 C CH4 and δ2 H CH4) measurements can be used to distinguish sources and thus to understand the CH 4 budget better. The CH 4 emission estimates by models are sensitive to the isotopic signatures assigned to each source category, so it is important to provide representative estimates of the different CH 4 source isotopic signatures worldwide. We present new measurements of isotope signatures of various, mainly anthropogenic, CH 4 sources in Europe, which represent a substantial contribution to the global dataset of source isotopic measurements from the literature, especially for δ2 H CH4. They improve the definition of δ13 C CH4 from waste sources, and demonstrate the use of δ2 H CH4 for fossil fuel source attribution. We combined our new measurements with the last published database of CH 4 isotopic signatures and with additional literature, and present a new global database. We found that microbial sources are generally well characterised. The large variability in fossil fuel isotopic compositions requires particular care in the choice of weighting criteria for the calculation of a representative global value. The global dataset could be further improved by measurements from African, South American, and Asian countries, and more measurements from pyrogenic sources. We improved the source characterisation of CH 4 emissions using stable isotopes and associated uncertainty, to be used in top-down studies. We emphasise that an appropriate use of the database requires the analysis of specific parameters in relation to source type and the region of interest. The final version of the European CH 4 isotope database coupled with a global inventory of fossil and non-fossil δ13 C CH4 and δ2 H CH4 source signature measurements is available at 10.24416/UU01-YP43IN. [ABSTRACT FROM AUTHOR]

Ambient weather conditions strongly impact contrail formation and persistence. The implementation of contrail avoidance and mitigation strategies, therefore, requires regional and altitude-dependent information on the frequency of contrail occurrence. To this end, we have developed a method to quantify the potential contrail cover based on 10 years of high-resolution reanalysis of climatology and weather data from the European Center for Medium-Range Weather Forecast (ECMWF). We use the Schmidt–Appleman threshold temperature for contrail formation and additionally select thresholds for the relative humidity to evaluate the occurrence of persistent contrails and assess their regional and seasonal variation. We find a potential contrail cirrus cover of 10% to 20% above Europe at higher altitudes of 200 and 250 hPa in the 10-year climatology and a weak seasonal variation. At lower altitudes, near 300 hPa, a steep onset and a high potential contrail cirrus cover of 20% is found in late fall and in winter, decreasing to 2% potential contrail cirrus cover in summer. In comparison to ECMWF data, evaluations using data from the National Centers for Environmental Prediction (NCEP) show a significantly lower potential contrail cirrus cover. Our results help to investigate the seasonal and altitude dependence of contrail mitigation strategies, in particular for warming nighttime contrails that contribute strongly to the total climate impact from aviation. [ABSTRACT FROM AUTHOR]

In resisting climate change, to what extent can lifestyle forms of activism be considered to be political? What are their determinants and to what extent do they differ from the determinants of other forms of action? What role do generational factors play? Does the centrality of lifestyle changes for young participants translate into a disaffection towards more traditional forms of action? This article explores the forms of action adopted by participants in two Fridays For Future (FFF) strikes, focusing on the repertoires of action of (young) climate justice protesters. We draw on protest survey data covering the FFF demonstrations held in 15 European countries in March and September 2019. Starting from a sharp generational contrast between the importance given to individual lifestyle changes in addressing the climate emergency, we investigate whether this results in significant generational differences in the choice of the repertoires of action. Challenging the vision of young people as 'disaffected citizens', it is demonstrated that young protesters do not participate less in claim-based action than older cohorts. Furthermore, a process of politicisation can be seen to be unfolding that leads to increased commitment in both lifestyle and political forms of participation – at least among active milieus. [ABSTRACT FROM AUTHOR]

Biochar (BC) is often proposed as a tool for climate change mitigation, due to the expected long lifetime in the environment. However, BC's stability can vary depending on feedstock type and the presence of labile carbon fractions. In this study, we verify the recent methods with new possible tools for biochar stability assessment on six different biochars derived from commonly available Europe biomass sources. Elemental composition (CHNO), dissolved organic carbon (DOC) and water-soluble carbonates content (WSC), volatile organic compounds (VOCs) composition, and mid-infrared spectra (MIR) were performed to estimate the persistence of biochars. Under similar conditions of pyrolysis, biochar properties can vary depending on a feedstock origin. Less aromatic structure and higher contents of labile carbon fractions (DOCs and WSC) in food waste biochars affected the lower stability, while biochars derived from high lignocellulose materials (straw, wood, and grass) were strongly carbonized, with persistent, aromatic structure. Labile carbon pool content (DOC, WSC) and spectral analysis can be useful tools for biochar stability assessment, giving similar information to the standard molar ratio method. Biochars obtained from agriculture and forestry management biomass should be considered as highly stable in soil and are appropriate for long-term carbon sequestration purposes. [ABSTRACT FROM AUTHOR]

Key message: Potential CH4 oxidation in the top soil layer increased with decreasing soil water content in spring but was inhibited during severe summer drought in naturally-regenerated oak-dominated temperate deciduous forest stands regardless of their age. No direct effect of mineral nitrogen on soil CH4 oxidation was found. Soil CH4 oxidation in temperate forests could be reduced by extreme climatic events. Context: The oxidation of atmospheric methane (CH4) by methanotrophic bacteria in forest soils is an important but overlooked ecosystem service. Aim: Our objective was to determine which factors drive variations in soil CH4 oxidation in oak-dominated temperate deciduous forest stands of different ages. Methods: Soil samples were collected in 16 stands aged 20 to 143 years in periods of high and low soil water content (SWC). The potential rate of soil CH4 oxidation was measured by incubating the first five centimetres of intact soil cores at 20 °C. Results: SWC was the main driver accounting for variations in CH4 oxidation. In spring, a two-fold reduction in SWC greatly increased CH4 oxidation. But when the soil was dry in late summer, a further reduction in SWC led to a decrease in CH4 oxidation in the top soil layer. No direct effect of mineral nitrogen on soil CH4 oxidation was found. Conclusions: With regard to soil CH4 oxidation, naturally regenerated forest stands contribute equally to climate change mitigation regardless of their age. Considering future climate scenarios for Europe, soil CH4 sink in temperate forests could be reduced, due to both an increase in the number of flooding episodes in spring and drier summers. [ABSTRACT FROM AUTHOR]

Decarbonizing heating in buildings is a key part of climate change mitigation policies, but deep retrofit is progressing slowly, e.g., at a pace of 0.2%/y of the building stock in Europe. By means of tests in two flats of a multiapartment housing complex recently renovated to very low values of energy needs, this paper explores the role of deep retrofitted buildings in providing energy flexibility services for the occupants/owners/managers and for the energy system. Key to this flexibility increase and capacity savings is the large reduction of energy needs for heating via a high level of external insulation, which allows the thermal capacity of the building mass to act as an energy storage, without the large energy losses presently affecting a large part of the building stock. Due to the limited number of case studies reporting experimental applications in real buildings, this research aims to offer an analysis based on a series of tests and detailed monitoring which show a significant increase in the time interval during which the low-energy-needs building remains in the comfort range, compared to a high-energy-needs building, when active delivery of energy is deactivated during the heating season. Intermittent renewable energy might hence be stored when available, thus enhancing the ability of the energy system to manage inherent variability of some renewable energy sources and/or increasing the share of the self-consumption of locally generated RES energy. Besides, two unplanned heating power outages which have involved the entire building complex allowed us to verify that deep retrofitted buildings are able to maintain thermally safe indoor conditions under extreme events, such as a power outage, for at least 5 days. [ABSTRACT FROM AUTHOR]

Mountain spruce forests in Central Europe decline under storms and bark beetle calamities driven by climate change. A stabilisation by planting rare or missing tree species is expensive and requires funding. A funding policy should mitigate climate change and support biodiversity. The goal of this study was to identify a conversion strategy of even-aged spruce-dominated forest stands to uneven-aged mixed stands with spruce (Picea abies (L.) H.Karst.), beech (Fagus sylvatica L.), and fir (Abies alba Mill.). A simultaneous nonlinear optimisation of the number of planted trees and harvested trees per species and per period schedules stand treatments aiming to maximise the long-term financial outcome. Planting modelling extends a density-dependent stand-level matrix transition model based on diameter classes with an age-class-based model for artificial regeneration. An optimal conversion strategy was applied for five funding policy schemes, each for five initial states representing different stages of age and species composition typical for spruce forest conversion in the mountain zone of the Western Carpathians. Only 50% and higher funding of planting costs for the minor/missing fir and beech species facilitates a substantial increase of their shares in stand volume. Funding decreases the volume failure due to mortality. Funding increases the standing and harvested volume, which mitigates climate change by increasing the carbon sequestration. Funding causes unintended effects on ecosystem services by lowering harvest diameters, decreasing the volume of less profitable beech, and temporarily reducing the stand density aimed at supporting plantings and their diameter increments. [ABSTRACT FROM AUTHOR]

The extensive use of fossil fuels in recent decades is a well-known cause of the climate crisis. Climate action inevitably requires the strategic reorientation of industries that are part of the fossil fuel regime. International oil companies are central to this regime and possess the incumbent's characteristic power and influence to steer this process. However, European international oil companies continue to invest in fossil fuels, even as they acknowledge the climate crisis imperative. Socio-political and economic dynamics can either reinforce the oil regime or pressure firms to take climate action. We aim to comprehensively analyse the dynamics between external socio-political and economic actors' pressures to climate action on the one side, and the industry response on the other, from 2005 to 2019, using Geels Triple Embeddedness Framework. Drawing on a wide range of qualitative and quantitative longitudinal data (e.g. regulations, oil and renewables market trends, companies' investments in oil, renewables, and low-carbon technologies), we characterised the pressures and responses of the different analytical categories and established three phases. The results indicate that policy pressure on the oil regime in this period lacked constancy and comprehensiveness. The Kyoto Protocol ratification produced an initial momentum that prompted some companies to invest in alternative fuels and renewables, but efforts faded after 2010. Societal calls for a transition from fossil fuels and divestments from oil companies have risen since 2017. Recent socio-economic pressures combined with policy pledges for net-zero emissions have prompted all companies to invest beyond fossil fuels. However, efforts are still marginal and additional advancements in climate policy are necessary to foster the renewables market and to promote the phase-out of oil. Key policy insights Europe lacks a comprehensive policy framework to support the fast deployment of available alternative fuels. Policies need to foster the development and adoption of alternatives to petrochemical products, alongside their reduction and recycling. Apart from supporting renewable energy and other alternatives to oil, policies also need to target the phase-out of oil and send a clear signal to companies. [ABSTRACT FROM AUTHOR]

This study focuses on the influence of related and unrelated variety on specialization in climate change mitigation technologies on a regional level in Europe. We consider two dimensions of specialization: the degree of specialization and being specialized or not. We also investigate the moderating role of public policy direction towards climate change mitigation at regional, national, and EU regime level. Based on a fixed effect specification of patent data relating to climate technologies in 194 regions during the period 2008–2017, we find that related variety positively influences the degree of specialization in climate technologies, but only in regions with a low degree of specialization. We also report a weakening effect of national policy level environmental taxation and of the European Regional Development Fund for related variety. Regarding being specialized as a region in climate technologies, our study reveals a positive role played by unrelated variety and a negative moderating effect exerted by both national policy level environmental taxation and European Regional Development Fund policy support. We discuss implications for policymaking in the field of climate change mitigation technologies. • We study the effect of variety on regional specialization in climate technologies. • We check related and unrelated variety and moderating effects of policy direction. • Related variety fosters specialization in regions with low degree of specialization. • Unrelated variety stimulates regional specialization in climate technologies. • Environmental taxation and ERDF support temper the positive effects of variety. [ABSTRACT FROM AUTHOR]

Unlocking the full potential of ponds (small water bodies) and pondscapes (network of ponds) as Nature-based Solutions (NbS) is critical pursuit for enhancing ecosystems and societal resilience to climate change and other societal challenges. Despite scattered initiatives for pond/pondscape creation, restoration and management—each considered here a distinct NbS—there is a significant knowledge gap in utilising ponds/pondscapes as effective NbS. We aimed to assess these NbS in terms of their objectives, outcomes, effectiveness, multifunctionality, delivery of potentially conflicting effects, and the implementation process while considering their Nature's Contributions to People (NCPs, i.e., benefits to society). We compiled data on 183 NbS actions implemented across 93 ponds/pondscapes from 24 countries, predominantly from Europe, via a questionnaire distributed to experienced stakeholders implementing NbS in ponds/pondscapes. One single pond/pondscape may imply more than one NbS action. Two-thirds were in rural areas, and one-third in urban settings. Our analysis revealed that Creation of habitat for biodiversity was a primary delivery objective (targeted NCP) in the implementation of most NbS in ponds/pondscapes, often also combined with other NCPs such as Learning and inspiration , Regulation of water quantity , and Physical and psychological experiences , showcasing their intended multifunctionality. Implemented NbS primarily focused on climate change adaptation (especially Regulation of hazards and extreme events , and water quantity) rather than mitigation, with less emphasis on measures like direct greenhouse gas emissions reduction or enhancing carbon sinks. The costs associated with pond's NbS varied significantly depending on factors such as project scope, objectives, location, socio-economic-cultural system, and specific implementation requirements. The creation of ponds/pondscapes often entailed the highest financial investment, much more than their restoration or their management. In conclusion, our study underscores the multifunctionality of ponds/pondscapes and provides insights about their significant potential as cost-effective NbS for enhancing ecosystem and societal resilience to climate change and biodiversity. It underscores the importance of further research to fully understand and measure the diverse range of NbS they offer, particularly in the context of climate change mitigation. Standardised measurements of the NCP provided by these NbS in ponds/pondscapes are essential for validating managers' claims and exploring their role in addressing climate change. Cascading Benefits of Natural-Based Solutions (NbS) in Ponds and Pondscapes: Ponds and pondscapes serve as multifunctional NbS, delivering multiple Nature's Contributions to People (NCPs) to address climate-related challenges and Sustainable Development Goals (SDGs). They regulate the water quantity, mitigating flood risks, and ensuring water availability during droughts. Furthermore, these NbS indirectly support climate change adaptation by preserving microclimates, buffering temperature fluctuations, and providing vital habitats for diverse species, enhancing ecosystem resilience. Simultaneously, these actions offer recreational, cultural, educational, and well-being benefits to local communities impacted by climate change. Despite their potential, the capacity of ponds and pondscapes for climate change mitigation through carbon sequestration and storage remains unknown, requiring further exploration. [Display omitted] • Global study of 183 Nature-based Solutions in ponds/pondscapes in 24 countries. • Pondscapes' Nature-based Solutions are multifunctional and prioritise biodiversity. • Emphasis on climate change adaptation rather than mitigation. • Ponds/pondscapes offer cost-effective Nature-based Solutions. • Need for standardised measures to validate claims and explore climate mitigation. [ABSTRACT FROM AUTHOR]

• The nexus between forest-based climate mitigation and health is poorly researched. • This scoping review identified exposure pathways and health co-benefits from forests. • There is potential for synergies between forest management and health benefits. • Interdisciplinary efforts are required for advancement of research and understanding. Climate change is a pressing global challenge with profound implications for human health. Forest-based climate change mitigation strategies, such as afforestation, reforestation, and sustainable forest management, offer promising solutions to mitigate climate change and simultaneously yield substantial co-benefits for human health. The objective of this scoping review was to examine research trends related to the interdisciplinary nexus between forests as carbon sinks and human health co-benefits. We developed a conceptual framework model, supporting the inclusion of exposure pathways, such as recreational opportunities or aesthetic experiences, in the co-benefit context. We used a scoping review methodology to identify the proportion of European research on forest-based mitigation strategies that acknowledge the interconnection between mitigation strategies and human impacts. We also aimed to assess whether synergies and trade-offs between forest-based carbon sink capacity and human co-benefits has been analysed and quantified. From the initial 4,062 records retrieved, 349 reports analysed European forest management principles and factors related to climate change mitigation capacity. Of those, 97 studies acknowledged human co-benefits and 13 studies quantified the impacts on exposure pathways or health co-benefits and were included for full review. Our analysis demonstrates that there is potential for synergies related to optimising carbon sink capacity together with human co-benefits, but there is currently a lack of holistic research approaches assessing these interrelationships. We suggest enhanced interdisciplinary efforts, using for example multideterminant modelling approaches, to advance evidence and understanding of the forest and health nexus in the context of climate change mitigation. [ABSTRACT FROM AUTHOR]