• Energy Research

Abstract Cities play a vital role in the global climate change mitigation agenda. City population density is one of the key factors that influence urban energy consumption and the subsequent GHG emissions. However, previous research on the relationship between population density and GHG emissions led to contradictory results due to urban/rural definition conundrum and the varying methodologies for estimating GHG emissions. This work addresses these ambiguities by employing the City Clustering Algorithm (CCA) and utilizing the gridded CO2 emissions data. Our results, derived from the analysis of all inhabited areas in the US, show a sub-linear relationship between population density and the total emissions (i.e. the sum of on-road and building emissions) on a per capita basis. Accordingly, we find that doubling the population density would entail a reduction in the total CO2 emissions in buildings and on-road sectors typically by at least 42%. Moreover, we find that population density exerts a higher influence on on-road emissions than buildings emissions. From an energy consumption point of view, our results suggest that on-going urban sprawl will lead to an increase in on-road energy consumption in cities and therefore stresses the importance of developing adequate local policy measures to limit urban sprawl.

AbstractReducing greenhouse gas emissions in food systems is becoming more challenging as food is increasingly consumed away from producer regions, highlighting the need to consider emissions embodied in trade in agricultural emissions accounting. To address this, our study explores recent trends in trade-adjusted agricultural emissions of food items at the global, regional, and national levels. We find that emissions are largely dependent on a country’s consumption patterns and their agricultural emission intensities relative to their trading partners’. The absolute differences between the production-based and trade-adjusted emissions accounting approaches are especially apparent for major agricultural exporters and importers and where large shares of emission-intensive items such as ruminant meat, milk products and rice are involved. In relative terms, some low-income and emerging and developing economies with consumption of high emission intensity food products show large differences between approaches. Similar trends are also found under various specifications that account for trade and re-exports differently. These findings could serve as an important element towards constructing national emissions reduction targets that consider trading partners, leading to more effective emissions reductions overall.

The world is facing a triple burden of undernourishment, obesity, and environmental impacts from agriculture while nourishing its population. This burden makes sustainable nourishment of the growing population a global challenge. Addressing this challenge requires an understanding of the interplay between diets, health, and associated environmental impacts (e.g., climate change). For this, we identify 11 typical diets that represent dietary habits worldwide for the last five decades. Plant-source foods provide most of all three macronutrients (carbohydrates, protein, and fat) in developing countries. In contrast, animal-source foods provide a majority of protein and fat in developed ones. The identified diets deviate from the recommended healthy diet with either too much (e.g., red meat) or too little (e.g., fruits and vegetables) food and nutrition supply. The total calorie supplies are lower than required for two diets. Sugar consumption is higher than recommended for five diets. Three and five diets consist of larger-than-recommended carbohydrate and fat shares, respectively. Four diets with a large share of animal-source foods exceed the recommended value of red meat. Only two diets consist of at least 400 gm/cap/day of fruits and vegetables while accounting for food waste. Prevalence of undernourishment and underweight dominates in the diets with lower calories. In comparison, a higher prevalence of obesity is observed for diets with higher calories with high shares of sugar, fat, and animal-source foods. However, embodied emissions in the diets do not show a clear relation with calorie supplies and compositions. Two high-calorie diets embody more than 1.5 t CO 2 eq/cap/yr, and two low-calorie diets embody around 1 t CO 2 eq/cap/yr. Our analysis highlights that sustainable and healthy diets can serve the purposes of both nourishing the population and, at the same time, reducing the environmental impacts of agriculture.

AbstractUrban climate is determined by a variety of factors, whose knowledge can help to attenuate heat stress in the context of ongoing urbanization and climate change. We study the influence of city size and urban form on the Urban Heat Island (UHI) phenomenon in Europe and find a complex interplay between UHI intensity and city size, fractality, and anisometry. Due to correlations among these urban factors, interactions in the multi-linear regression need to be taken into account. We find that among the largest 5,000 cities, the UHI intensity increases with the logarithm of the city size and with the fractal dimension, but decreases with the logarithm of the anisometry. Typically, the size has the strongest influence, followed by the compactness, and the smallest is the influence of the degree to which the cities stretch. Accordingly, from the point of view of UHI alleviation, small, disperse, and stretched cities are preferable. However, such recommendations need to be balanced against e.g. positive agglomeration effects of large cities. Therefore, trade-offs must be made regarding local and global aims.

Les impacts du changement climatique devraient devenir plus intenses et plus fréquents. L'un des impacts indirects du changement climatique est l'insécurité alimentaire. L'agriculture au Pakistan, classée quatrième au monde, subit déjà les effets néfastes visibles du changement climatique. Parmi de nombreuses autres sources de nourriture, la culture de la pomme de terre reste l'une des cultures de sécurité alimentaire des pays en développement. Les pommes de terre sont largement cultivées au Pakistan. Pour évaluer l'impact du changement climatique sur les cultures de pommes de terre au Pakistan, il est impératif d'analyser sa répartition dans le cadre de futurs scénarios de changement climatique à l'aide de modèles de répartition des espèces (SDM). Le modèle d'entropie maximale est utilisé dans cette étude pour prédire la distribution spatiale de la pomme de terre en 2070 à l'aide de deux modèles CMIP5 pour deux scénarios de changement climatique (RCP 4.5 et RCP 8.5). 19 Les variables bioclimatiques sont incorporées avec d'autres variables contributives telles que le type de sol, l'altitude et l'irrigation. Les résultats indiquent une légère diminution de la zone appropriée pour la croissance de la pomme de terre dans le RCP 4.5 et une diminution drastique de la zone appropriée dans le RCP 8.5 pour les deux modèles. L'évaluation des performances du modèle est basée sur l'AUC. La valeur de l'ASC de 0,85 suggère l'adéquation du modèle et, par conséquent, il est applicable pour prédire le climat approprié pour la production de pommes de terre au Pakistan. La culture durable de la pomme de terre est nécessaire pour augmenter la productivité dans les pays en développement tout en favorisant une meilleure gestion et optimisation des ressources. Se prevé que los impactos del cambio climático sean más intensos y frecuentes. Uno de los impactos indirectos del cambio climático es la inseguridad alimentaria. La agricultura en Pakistán, que ocupa el cuarto lugar en el mundo, ya está experimentando efectos adversos visibles del cambio climático. Entre muchas otras fuentes de alimentos, el cultivo de papa sigue siendo uno de los cultivos de seguridad alimentaria para las naciones en desarrollo. Las papas se cultivan ampliamente en Pakistán. Para evaluar el impacto del cambio climático en el cultivo de papa en Pakistán, es imperativo analizar su distribución en escenarios futuros de cambio climático utilizando Modelos de Distribución de Especies (SDM). El modelo de entropía máxima se utiliza en este estudio para predecir la distribución espacial de la papa en 2070 utilizando dos modelos CMIP5 para dos escenarios de cambio climático (RCP 4.5 y RCP 8.5). 19 Se incorporan variables bioclimáticas junto con otras variables contribuyentes como tipo de suelo, elevación y riego. Los resultados indican una ligera disminución en el área adecuada para el crecimiento de la papa en RCP 4.5 y una disminución drástica en el área adecuada en RCP 8.5 para ambos modelos. La evaluación del rendimiento del modelo se basa en el AUC. El valor de AUC de 0,85 sugiere la idoneidad del modelo y, por lo tanto, es aplicable para predecir el clima adecuado para la producción de papa en Pakistán. El cultivo sostenible de la papa es necesario para aumentar la productividad en los países en desarrollo y, al mismo tiempo, promover una mejor gestión y optimización de los recursos. The impacts of climate change are projected to become more intense and frequent. One of the indirect impacts of climate change is food insecurity. Agriculture in Pakistan, measured fourth best in the world, is already experiencing visible adverse impacts of climate change. Among many other food sources, potato crop remains one of the food security crops for developing nations. Potatoes are widely cultivated in Pakistan. To assess the impact of climate change on potato crop in Pakistan, it is imperative to analyze its distribution under future climate change scenarios using Species Distribution Models (SDMs). Maximum Entropy Model is used in this study to predict the spatial distribution of Potato in 2070 using two CMIP5 models for two climate change scenarios (RCP 4.5 and RCP 8.5). 19 Bioclimatic variables are incorporated along with other contributing variables like soil type, elevation and irrigation. The results indicate slight decrease in the suitable area for potato growth in RCP 4.5 and drastic decrease in suitable area in RCP 8.5 for both models. The performance evaluation of the model is based on AUC. AUC value of 0.85 suggests the fitness of the model and thus, it is applicable to predict the suitable climate for potato production in Pakistan. Sustainable potato cultivation is needed to increase productivity in developing countries while promoting better resource management and optimization. من المتوقع أن تصبح آثار تغير المناخ أكثر كثافة وتكرارًا. أحد الآثار غير المباشرة لتغير المناخ هو انعدام الأمن الغذائي. الزراعة في باكستان، التي تقاس بأنها رابع أفضل زراعة في العالم، تعاني بالفعل من آثار ضارة واضحة لتغير المناخ. من بين العديد من المصادر الغذائية الأخرى، لا يزال محصول البطاطس أحد محاصيل الأمن الغذائي للدول النامية. تزرع البطاطس على نطاق واسع في باكستان. لتقييم تأثير تغير المناخ على محصول البطاطس في باكستان، من الضروري تحليل توزيعه في ظل سيناريوهات تغير المناخ المستقبلية باستخدام نماذج توزيع الأنواع (SDMs). يستخدم نموذج الانتروبي الأقصى في هذه الدراسة للتنبؤ بالتوزيع المكاني للبطاطس في عام 2070 باستخدام نموذجين CMIP5 لسيناريوهين لتغير المناخ (RCP 4.5 و RCP 8.5). 19 يتم دمج المتغيرات المناخية الحيوية جنبًا إلى جنب مع المتغيرات المساهمة الأخرى مثل نوع التربة والارتفاع والري. تشير النتائج إلى انخفاض طفيف في المساحة المناسبة لنمو البطاطس في RCP 4.5 وانخفاض حاد في المساحة المناسبة في RCP 8.5 لكلا النموذجين. يعتمد تقييم أداء النموذج على الجامعة الأمريكية بالقاهرة. تشير قيمة المساحة تحت المنحنى البالغة 0.85 إلى ملاءمة النموذج، وبالتالي، فهي قابلة للتطبيق للتنبؤ بالمناخ المناسب لإنتاج البطاطس في باكستان. هناك حاجة إلى زراعة البطاطس المستدامة لزيادة الإنتاجية في البلدان النامية مع تعزيز إدارة الموارد وتحسينها.

Human mortality shows a pronounced temperature dependence. The minimum mortality temperature (MMT) as a characteristic point of the temperature-mortality relationship is influenced by many factors. As MMT estimates are based on case studies, they are sporadic, limited to data-rich regions, and their drivers have not yet been clearly identified across case studies. This impedes the elaboration of spatially comprehensive impact studies on heat-related mortality and hampers the temporal transfer required to assess climate change impacts. Using 400 MMTs from cities, we systematically establish a generalised model that is able to estimate MMTs (in daily apparent temperature) for cities, based on a set of climatic, topographic and socio-economic drivers. A sigmoid model prevailed against alternative model setups due to having the lowest Akaike Information Criterion (AICc) and the smallest RMSE. We find the long-term climate, the elevation, and the socio-economy to be relevant drivers of our MMT sample within the non-linear parametric regression model. A first model application estimated MMTs for 599 European cities (>100 000 inhabitants) and reveals a pronounced decrease in MMTs (27.8-16 °C) from southern to northern cities. Disruptions of this pattern across regions of similar mean temperatures can be explained by socio-economic standards as noted for central eastern Europe. Our alternative method allows to approximate MMTs independently from the availability of daily mortality records. For the first time, a quantification of climatic and non-climatic MMT drivers has been achieved, which allows to consider changes in socio-economic conditions and climate. This work contributes to the comparability among MMTs beyond location-specific and regional limits and, hence, towards a spatially comprehensive impact assessment for heat-related mortality.

This study explores the potential for regions to shift to a local food supply using food self-sufficiency (FSS) as an indicator. We considered a region food self-sufficient when its total calorie production is enough to meet its demand. For future scenarios, we considered population growth, dietary changes, improved feed conversion efficiency, climate change, and crop yield increments. Starting at the 5' resolution, we investigated FSS from the lowest administrative levels to continents. Globally, about 1.9 billion people are self-sufficient within their 5' grid, while about 1 billion people from Asia and Africa require cross-continental agricultural trade in 2000. By closing yield gaps, these regions can achieve FSS, which also reduces international trade and increases a self-sufficient population in a 5' grid to 2.9 billion. The number of people depending on international trade will vary between 1.5 and 6 billion by 2050. Climate change may increase the need for international agricultural trade by 4% to 16%.