• Energy Research

AbstractUnderstanding climate‐cropland interactions and their impact on future projections in West Africa motivated the recent development of a modeling framework that asynchronously couples four models for regional climate, crop growth, socioeconomics, and cropland allocation. This modeling framework can be applied to a future time slice using an equilibrium approach or to a continuous projection using a transient approach. This paper compares the differences between these two approaches, examines the transient dynamics of the system, and evaluates its impact on future projections. During the course of projection up to mid‐century, food demand is projected to increase monotonically, while the projected crop yield shows a high degree of temporal dynamics due to strong climate variability. Such temporal dynamics are not accounted for by the equilibrium approach. As a result, the transient approach projects a generally faster future expansion of cropland, with the largest differences over Benin, Burkina Faso, Ghana, Senegal, and Togo. Despite the relative large differences between the two approaches in projecting land cover changes associated with cropland expansion, the projected future climate changes are fairly similar. While the additional cropland expansion in the transient approach favors a wet signal, both the transient and equilibrium approaches project a future decrease of rainfall in the western part of West Africa and an increase in the eastern part. For quantifying climate changes, the equilibrium application of the modeling framework is likely to be sufficient; for assessing climate impact on agricultural sectors and devising mitigation and adaptation strategies, transient dynamics is important.

Accurate information on cropland extent is critical for scientific research and resource management. Several cropland products from remotely sensed datasets are available. Nevertheless, significant inconsistency exists among these products and the cropland areas estimated from these products differ considerably from statistics. In this study, we propose a hierarchical optimization synergy approach (HOSA) to develop a hybrid cropland map of China, circa 2010, by fusing five existing cropland products, i.e., GlobeLand30, Climate Change Initiative Land Cover (CCI-LC), GlobCover 2009, MODIS Collection 5 (MODIS C5), and MODIS Cropland, and sub-national statistics of cropland area. HOSA simplifies the widely used method of score assignment into two steps, including determination of optimal agreement level and identification of the best product combination. The accuracy assessment indicates that the synergy map has higher accuracy of spatial locations and better consistency with statistics than the five existing datasets individually. This suggests that the synergy approach can improve the accuracy of cropland mapping and enhance consistency with statistics.

Abstract Dams have often been constructed for hydropower, water storage and to support socio-economic development, particularly in areas of water stress. In many places, the water stored in human-made reservoirs is essential to meet the development objectives of water supply, agriculture, industry, energy generation and other sectors. However, in the absence of adequate foresight and planning, many past dams have had considerable negative impacts on ecosystems and the livelihoods of affected communities, resulting in conflicts and health hazards. While enhanced human health and well-being could be considered as the ultimate outcome of development programs, the public health impact of dams remains an issue that is often neglected by policy makers and investors. National policies and international guidelines, such as those of the World Commission on Dams, have been used to improve planning and impact assessment of dams. Here, we provide an analysis of four large dams, across three continents, and show that they had limited consistency with World Commission on Dams principles and guidelines. Moreover, health aspects were largely neglected during planning, construction and operation of these dams, but seriously undermine their intended benefits. This perspective paper discusses impacts of dams on energy and food, ecosystem health, inclusion, and ultimately human health and wellbeing. We argue that a One Health perspective, based on these four categories, can support the systematic consideration of environmental, animal, and human health determinants. A dedicated One Health approach to dams and reservoirs remains to be developed but could potentially improve how dams, both existing and future, support more inclusive development.

In the context of climate change, assessing spatiotemporal dynamics of crop production is becoming an important component of food security, which is one of the United Nations Sustainable Development Goals. Wheat is a major staple food that is grown worldwide. Although many studies have analyzed wheat production, spatial analyses, particularly geographical centroid (GC) studies, are rare. The GC studies are of important scientific value and policy implications. This study aims to estimate the GC movement of wheat area (including winter and spring wheat) from 1949 to 2014 in China (the largest wheat-producing country). A centroid model was adopted to measure GC movements, and then a regression analysis was conducted to understand the driving factors of wheat area changes (as area changes lead to GC movement). Then multiple scenario analyses were built to study GC movement driven by climatic factors alone. The net GC movements of winter and spring wheat area were estimated at 31 km northwestward and 692 km southwestward from 1949 to 2014, with both displaying a turning point in their movement routes around 1970s (the GC of winter wheat area moved 89 km before 1970s and 66 km after 1970s; while the GC of spring wheat area moved 89 km before 1970s and 799 km after 1970s); furthermore, the major driving factor of winter wheat GC movement is a socioeconomic factor (i.e., expanded irrigation area) while that of spring wheat GC movement is a climatic factor (i.e., temperature) among the factors considered in this study. Our “climate only” scenarios highlighted that the impact of temperature on GC movement of winter wheat is more significant than that of precipitation. We assessed the spatiotemporal movement of wheat area to better understand its production dynamics in response to climate change and human activities. This study provides scientific evidence for policymakers and related stakeholders in China and other countries regarding food production patterns and planting decisions.

Les événements extrêmes, tels que ceux causés par le changement climatique, les chocs économiques ou géopolitiques et les épidémies de ravageurs ou de maladies, menacent la sécurité alimentaire mondiale. La complexité de la causalité, ainsi que la myriade de façons dont un événement, ou une séquence d'événements, crée des impacts en cascade et systémiques, posent des défis importants à la recherche sur les systèmes alimentaires et aux politiques. Pour identifier les risques prioritaires pour la sécurité alimentaire et les opportunités de recherche, nous avons demandé à des experts de divers domaines et régions géographiques de décrire les principales menaces pour la sécurité alimentaire mondiale au cours des deux prochaines décennies et de suggérer des questions et des lacunes de recherche clés sur ce sujet. Nous présentons ici une hiérarchisation des menaces à la sécurité alimentaire mondiale résultant d'événements extrêmes, ainsi que des questions de recherche émergentes qui mettent en évidence les défis conceptuels et pratiques qui existent dans la conception, l'adoption et la gouvernance de systèmes alimentaires résilients. Nous espérons que ces résultats aideront à orienter le financement de la recherche et les ressources vers les transformations du système alimentaire nécessaires pour aider la société à faire face aux principaux risques du système alimentaire et à l'insécurité alimentaire en cas d'événements extrêmes. Los eventos extremos, como los causados por el cambio climático, las crisis económicas o geopolíticas y las epidemias de plagas o enfermedades, amenazan la seguridad alimentaria mundial. La complejidad de la causalidad, así como las innumerables formas en que un evento, o una secuencia de eventos, crea impactos en cascada y sistémicos, plantea desafíos significativos para la investigación y las políticas de los sistemas alimentarios por igual. Para identificar los riesgos prioritarios para la seguridad alimentaria y las oportunidades de investigación, pedimos a expertos de una variedad de campos y geografías que describieran las amenazas clave para la seguridad alimentaria mundial en las próximas dos décadas y que sugirieran preguntas y brechas clave de investigación sobre este tema. Aquí, presentamos una priorización de las amenazas a la seguridad alimentaria mundial derivadas de eventos extremos, así como preguntas de investigación emergentes que resaltan los desafíos conceptuales y prácticos que existen para diseñar, adoptar y gobernar sistemas alimentarios resilientes. Esperamos que estos hallazgos ayuden a dirigir la financiación de la investigación y los recursos hacia las transformaciones del sistema alimentario necesarias para ayudar a la sociedad a abordar los principales riesgos del sistema alimentario y la inseguridad alimentaria en situaciones extremas. Extreme events, such as those caused by climate change, economic or geopolitical shocks, and pest or disease epidemics, threaten global food security. The complexity of causation, as well as the myriad ways that an event, or a sequence of events, creates cascading and systemic impacts, poses significant challenges to food systems research and policy alike. To identify priority food security risks and research opportunities, we asked experts from a range of fields and geographies to describe key threats to global food security over the next two decades and to suggest key research questions and gaps on this topic. Here, we present a prioritization of threats to global food security from extreme events, as well as emerging research questions that highlight the conceptual and practical challenges that exist in designing, adopting, and governing resilient food systems. We hope that these findings help in directing research funding and resources toward food system transformations needed to help society tackle major food system risks and food insecurity under extreme events. وتهدد الأحداث المتطرفة، مثل تلك الناجمة عن تغير المناخ والصدمات الاقتصادية أو الجيوسياسية وأوبئة الآفات أو الأمراض، الأمن الغذائي العالمي. إن تعقيد السببية، فضلاً عن الطرق التي لا تعد ولا تحصى التي يخلق بها الحدث، أو سلسلة من الأحداث، تأثيرات متتالية ومنهجية، تشكل تحديات كبيرة لبحوث وسياسات النظم الغذائية على حد سواء. لتحديد مخاطر الأمن الغذائي ذات الأولوية وفرص البحث، طلبنا من خبراء من مجموعة من المجالات والمناطق الجغرافية وصف التهديدات الرئيسية للأمن الغذائي العالمي على مدى العقدين المقبلين واقتراح أسئلة وثغرات بحثية رئيسية حول هذا الموضوع. هنا، نقدم أولوية للتهديدات التي يتعرض لها الأمن الغذائي العالمي من الأحداث المتطرفة، بالإضافة إلى أسئلة البحث الناشئة التي تسلط الضوء على التحديات المفاهيمية والعملية الموجودة في تصميم وتبني وإدارة النظم الغذائية المرنة. نأمل أن تساعد هذه النتائج في توجيه تمويل البحوث والموارد نحو تحولات النظام الغذائي اللازمة لمساعدة المجتمع على معالجة المخاطر الرئيسية للنظام الغذائي وانعدام الأمن الغذائي في ظل الأحداث المتطرفة.

Agrochemicals are overused in China. One strategy to reduce agrochemical use is to increase farm size because of the potential effect of economy of scale. Existing studies at a micro scale present mixed and often conflicting results on the relationship between agrochemical use and farm size. This study aimed to assess that relationship from a macro perspective using an aggregated panel dataset in 30 provinces in China from 2009 to 2016. The empirical results confirm the existence of both economy and diseconomy of scale effects on agrochemical use in China. The agrochemical application rates decreased as the proportion of farms between 0.667 and 2 ha increased. The diseconomy of scale existed when significantly larger farms, such as the farms larger than 3.34 ha, continued to emerge. Given the fact that 78.6% of farms are under 0.667 ha in China, our results suggest that the reduction strategy based on only expanding farm size might achieve some initial success in reducing agrochemical use, but the effect would fade away and be reversed as significantly large farms continue to emerge. These results have significant policy implications as China is proactively developing and implementing various policies and strategies to modernize its agriculture toward achieving its sustainability goals.