In our globalised food system, farmers meet domestic and transboundary food needs. As a result, the contribution of farmers to domestic food production is a poor proxy for their role in national... Show moreIn our globalised food system, farmers meet domestic and transboundary food needs. As a result, the contribution of farmers to domestic food production is a poor proxy for their role in national food security. This study offers the first global assessment of how small-, medium-, and large-scale farmers contribute to global food security. We find that the role of small-scale farmers in national and global food security has been significantly underestimated due to the localised focus of previous studies, particularly in high-income nations. Future research must account for the differentiated roles, impacts, and vulnerabilities of farmers within a global context. Show less
Scenarios that limit global warming to 1.5°C rely on a combination of interventions to reduce greenhouse gas emissions and capture carbon dioxide. However, the extent to which lifestyle change... Show moreScenarios that limit global warming to 1.5°C rely on a combination of interventions to reduce greenhouse gas emissions and capture carbon dioxide. However, the extent to which lifestyle change contributes to mitigation relative to technological change over time remains understudied. Here, we present a scenario model that incorporates extensive supply-side technological transformations while excluding lifestyle changes. By adapting a global supply-use table from EXIOBASE using elements from Shared Socioeconomic Pathway 1 and a mitigation pathway consistent with the 1.5°C target, we assess how household footprints evolve in 2030 and 2050 and the extent to which technological change alone can mitigate greenhouse gas emissions. We modeled footprints for 49 countries/regions, with a focus on the EU27. Our scenario results indicate that while technological change can substantially reduce emissions, the reductions are ultimately insufficient to achieve the 1.5°C target. Eight EXIOBASE regions, including three EU27 countries, are on a 1.5°C-consistent trajectory with just technological advancements in 2030. However, by 2050, no countries are projected to meet the 1.5°C-compatible target. The average EU27 overshoot for household footprints approaches 2.2 tCO2e/cap in 2030 and 3.1 tCO2e/cap in 2050. Global overshoots are more moderate at 0.3 tCO2e/cap in 2030 and 2.0 tCO2e/cap in 2050. Our results highlight the critical role of household lifestyle transformation in climate change mitigation. Future research can explore the diverse lifestyle change pathways necessary to align with the aspirational 1.5°C target outlined in the Paris Agreement. Show less
Meiracker, R. van den; Wesdorp K.; Tamis, W.L.M.; Zelfde, M. van 't; Visser, M.D. 2024
The increase in food demand and limited opportunities to expand agricultural land pose a threat to local and global food security. Producing food in urban areas such as green roofs can help satisfy... Show moreThe increase in food demand and limited opportunities to expand agricultural land pose a threat to local and global food security. Producing food in urban areas such as green roofs can help satisfy urban food demand and thus alleviate pressure on agricultural land. However, a modeling framework that simulates crop growth and production potential on green roofs at a city scale is missing. Here, we adapt the Aquacrop model to explore the growth potential of various types of crops on green roofs and apply it to suitable roof areas in the city of Amsterdam. Our modeling framework includes irrigation methods for water use on green roofs that are optimized according to various climate-driven scenarios of water availability. We find that cabbage has the maximum achievable crop yields ranging from 30.8 to 75.9 t ha-1 yr-1, while pea has the minimum achievable crop yields ranging from 1.7 to 6.4 t ha-1 yr-1. The potential suitable green roof area (i.e., roofs with a certain slope and bearing capacity) for Amsterdam is roughly 400 ha for crop production. This represents 16 % of the total rooftop areas of Amsterdam and can produce up to a total of 28 kt of crops on an annual basis. Our modeling framework can be easily applied to other cities to identify the crop growth potential of green roofs. Our results can help policymakers and urban planners find optimal planting strategies and contribute to shorter food supply chains. Show less
Geukes, H.H.; Bodegom, P.M. van; Oudenhoven, A.P.E. van 2024
Nature-based solutions (NbS) are fast becoming the norm for multifunctional coastal climate adaptation to increased sea-level rise. However, informing decision-makers about NbS presents ongoing... Show moreNature-based solutions (NbS) are fast becoming the norm for multifunctional coastal climate adaptation to increased sea-level rise. However, informing decision-makers about NbS presents ongoing challenges. This study set out to identify and explore the information requirements at different stages of the decision-making process of coastal NbS. Developing and applying a novel methodological approach, we analysed the values and indicators discussed in four key decision-making stages: the advocacy, political, bureaucratic and provisioning stages. Applied to a mega beach nourishment in the Netherlands, our study identified substantial differences in information requirements across the decision-making stages. Most notably, the values and indicators discussed shifted from being abstract to becoming increasingly specific and concrete as the stages progressed. Our findings emphasize the importance of recognizing the distinct stages of decision-making and tailoring the content and level of abstraction of information accordingly. Additionally, they suggest that future changes in the content and concretisation of the information required for decision-making on coastal NbS can be anticipated and prepared for. By distinguishing and understanding the decision-making stages in NbS, this study bridges a longstanding gap between decision-making and NbS studies, thereby allowing for improving the fairness, implementation, evaluation and comprehension of trade-offs of coastal NbS. This study progresses the understanding of the information required for planning, implementing, evaluating and managing coastal NbS, advancing multifunctional coastal climate adaptation for shores worldwide. Show less
Musters, C.J.M.; Honkoop, H.P.; Snoo, G.R. de 2024
n decision making for insect conservation, one depends largely on knowledge of the relationship between changes in environmental factors and abundance of a very limited number of species. The... Show moren decision making for insect conservation, one depends largely on knowledge of the relationship between changes in environmental factors and abundance of a very limited number of species. The species we have knowledge on cannot be regarded as a representative sample of all insects. How accurately do changes in the abundance of these species predict the changes in other species? To answer this question, we studied 373 insect species belonging to the Apidae (bees), Lepidoptera (butterflies), Orthoptera (grasshoppers), Ephemeroptera (mayflies), Trichoptera (caddisflies), Odonata (dragonflies), and Plecoptera (stoneflies), with known population trends and attributes in the Netherlands. The 78 attributes included morphological and demographic trait values, as well as habitat requirements of species. We trained Random Forests (RFs) with random samples and with taxonomic groups to predict the decline of the species based on their attributes. Then we used the trained RFs to predict the decline of the species outside the training groups and checked the accuracy of the predictions. The results showed that accuracy of the predictions of the RFs trained by the random samples increased from 0 to 0.20 (maximum 0.40, on a scale of 0 to 1) with sample size increasing from 10 to 90% of the insects. Moreover, we found that the accuracy of the predictions by the RFs trained with the taxonomic groups were zero in case of butterflies and grasshoppers, and low in other groups (maximum 0.37, in case of bees predicting terrestrial insects). Accuracy depended significantly on the size of the taxonomic group. Large over- or underestimation of number of declining species occurred in all cases. Further, we found that the taxonomic groups had few attributes important for predicting in common. The attribute ‘Active dispersion’ had the highest importance when all insects were used for training the RF. Using ‘indicator groups’ for predicting the decline of insects has a high risk of over- or underestimating the actual number of declining species and should therefore be advised against unless the indicator group is sure to be representative. Show less
Sodium-ion batteries (SIBs) have emerged as an alternative to lithium-ion batteries (LIBs) due to their promising performance in terms of battery cycle lifetime, safety, operating in wider... Show moreSodium-ion batteries (SIBs) have emerged as an alternative to lithium-ion batteries (LIBs) due to their promising performance in terms of battery cycle lifetime, safety, operating in wider temperature range, as well as the abundant and low-cost of sodium resources. This study evaluated the climate impacts of three SIBs, and compared to two LIBs under four scenarios with considering potential changes in battery performance and background productions between 2020 and 2050. To ensure a fair comparison, all batteries were modeled in the 21,700 form, and a battery dimensioning model was developed to calculate the required amount of components for each battery. We found that equal to lower GHG emissions result from the use of SIBs compared to LIBs under optimal performance scenarios. From 2020 to 2050, the climate impacts of SIBs decreased by 43–57 %. The relative contribution of the battery manufacturing process decreases from 18–32 % to 2–4 % due to the increasingly share of clean energy in the electricity grid, while the relative contribution of key battery component materials increases over time, especially for cathode active materials. These results emphasize the significance of decarbonizing the electric grid, and suggest that future investment in SIBs is promising from an environmental point of view. Show less
Suburban sprawl emerged during the 20th century alongside the widespread ownership of cars. This type of low-density housing generates enduring car dependency due to the long lifetimes of buildings... Show moreSuburban sprawl emerged during the 20th century alongside the widespread ownership of cars. This type of low-density housing generates enduring car dependency due to the long lifetimes of buildings. A more sustainable mobility system would require a deep transformation to densify urban forms and thus foster proximity of homes, work, and services. Here we explore the evolution of long-lived residential building stocks and the potential for breaking of this lock-in by selective demolishing of detached houses to densify urban forms. We assess impacts on land use, material demand and stocks, and greenhouse gas emissions. We use a novel dynamic, Material Flow Analysis (MFA) model applied to a Swedish case study that accounts for the co-relations of building stock and car fleets through residential density. The model includes different municipality types and we explore three different speeds for the change in urban form. An accelerated densification requires more bulk materials in construction but fewer scarcer materials in cars. However, the up-front emissions of accelerated densification construction are only compensated by mobility savings in the long-term, by 2100. Emissions trends for the three scenarios are far from the urgent decarbonisation necessary. However, the denser final built environments may have social benefits and can free up significant land. Show less
The aviation sector needs to reduce its environmental impacts, like climate change and air pollution. New hybrid-electric aircraft concepts may contribute to abating part of these impacts. But to... Show moreThe aviation sector needs to reduce its environmental impacts, like climate change and air pollution. New hybrid-electric aircraft concepts may contribute to abating part of these impacts. But to what extent and under which conditions? This study addresses these questions in the context of regional aviation and identifies technologies and concrete actions required for more environmentally sustainable aviation. The environmental impacts of emerging hybrid-electric aircraft configurations deployed in 2030, 2040, and 2050 have been comprehensively quantified using prospective life cycle assessment. The entire life cycle of the conventional and hybrid-electric aircraft configurations was encompassed, covering various technologies and systems like batteries, fuel cells, hydrogen, and selected alternative aviation fuel (AAF) systems. For these elements, detailed life cycle inventories stemming from primary data, literature, and prospective environmental databases were used, and uncertainty was evaluated. Results showed that hybrid-electric aircraft with Li-ion batteries appear as a promising transition technology in the short-term while aircraft propelled by fuel cells using hydrogen from electrolysis yield important environmental benefits relative to conventional aircraft in longer time horizons. In contrast, the studied AAFs present little or no environmental benefits when considering environmental impacts holistically, demonstrating the need to revise existing AAF frameworks and incentives globally. Environmental burden-shifting from flight emissions in conventional aircraft systems to airport operations and aircraft manufacturing in hybrid-electric aircraft is also observed in the results, thus calling for strengthened support to airports in their sustainability management and increased integration of ecodesign practices in future aircraft design and development. Show less
Engelenburg, M. van; Deetman, S.P.; Fishman, T.; Behrens, P.A.; Voet, E. van der 2024
Construction materials are associated with significant environmental and resource impacts. The circular use of materials already in use as stocks may provide an opportunity to reduce these impacts.... Show moreConstruction materials are associated with significant environmental and resource impacts. The circular use of materials already in use as stocks may provide an opportunity to reduce these impacts. We provide a dataset describing the potential global urban mine consisting of transportation infrastructure in an open database based on geospatial data from OpenStreetMaps. We reveal the significant opportunities of the embedded materials in this huge stock. With this Total Resources in Physical Infrastructure, or TRIPI, the database we provide easy access to a global dataset covering 175 countries and sub-regions, allowing researchers to select an area of study, and find the location as well as the material composition of the physical infrastructure. Material stocks are reported on a national level and commonly used regional aggregations. Material stocks are reported per kg, kg per capita, and kg per area; and for the physical type of infrastructure that is available in kilometres and area (km2). This dataset can be used in various research applications such as Material Flow Analysis, Material stock inventories, Country-level comparisons of infrastructure density, and others, and inform policy on harnessing the opportunities of the urban mine. Show less
Oever, A.E.M. van den; Puricelli, S.; Costa, D.; Thonemann, N.; Philippot, M.L.; Messagie, M. 2024
Recent works have highlighted the interconnected impacts of stratospheric ozone depletion, ultraviolet (UV) radiation, and climate change on various sectors, including water quality, agriculture,... Show moreRecent works have highlighted the interconnected impacts of stratospheric ozone depletion, ultraviolet (UV) radiation, and climate change on various sectors, including water quality, agriculture, human health, and biodiversity. Increased UV-B exposure has diverse environmental impacts, including potential benefits like enhanced plant resistance and reduced vitamin D deficiency. However, the quantification of these effects remains incomplete. Life Cycle Assessment (LCA) serves to quantify the environmental impacts of product systems. This article revisits challenges related to ozone depletion in LCA by reviewing 15 Life Cycle Impact Assessment (LCIA) methods. It is shown that the currently available LCA ozone depletion practices are outdated. The combined effects of outdated background databases and incomplete impact assessment methods must be further investigated. Collaboration with atmospheric scientists and expansion of substances covered by characterization models are required. The study emphasizes the need to address interlinkages between impact categories and recommends climate scenario-dependent characterization for robust decision-making in an uncertain world. Show less
PurposeSome future-oriented life cycle assessment (LCA) terms, particularly prospective and ex-ante, show notable increase in use in publications over the last decade. However, scholars have... Show morePurposeSome future-oriented life cycle assessment (LCA) terms, particularly prospective and ex-ante, show notable increase in use in publications over the last decade. However, scholars have pointed out that it is currently unclear exactly what these terms mean and how they are related. This paper aims to explain defining differences between future-oriented LCA terms and provide terminology recommendations.MethodsExisting definitions of future-oriented LCA terms were reviewed and analyzed. Workshops were held where defining differences of future-oriented LCA terms were discussed.ResultsTemporal positionality and technology maturity appear to be two critical aspects of future-oriented LCA. Prospective and ex-ante LCA are similar, with the possible difference that ex-ante LCA always involves an increase in technology maturity in the future. Considering the notable similarities, it seems reasonable to converge terms to mitigate field fragmentation and avoid terminology confusion.ConclusionsTo denote LCA studies with a future temporal positionality, we recommend using the term prospective LCA, defined as “LCA that models the product system at a future point in time relative to the time at which the study is conducted”. Furthermore, since technology maturity is clearly a critical aspect for prospective LCA, we recommend prospective LCA studies to clearly define the maturity of the technologies modeled in the production system. Show less
