• Energy Research

AbstractIn a changing climate arising from anthropogenic global warming, the nature of extreme climatic events is changing over time. Existing analytical stationary-based risk methods, however, assume multi-dimensional extreme climate phenomena will not significantly vary over time. To strengthen the reliability of infrastructure designs and the management of water systems in the changing environment, multidimensional stationary risk studies should be replaced with a new adaptive perspective. The results of a comparison indicate that current multi-dimensional stationary risk frameworks are no longer applicable to projecting the changing behaviour of multi-dimensional extreme climate processes. Using static stationary-based multivariate risk methods may lead to undesirable consequences in designing water system infrastructures. The static stationary concept should be replaced with a flexible multi-dimensional time-varying risk framework. The present study introduces a new multi-dimensional time-varying risk concept to be incorporated in updating infrastructure design strategies under changing environments arising from human-induced climate change. The proposed generalized time-varying risk concept can be applied for all stochastic multi-dimensional systems that are under the influence of changing environments.

Abstract California has experienced devastating autumn wildfires in recent years. These autumn wildfires have coincided with extreme fire weather conditions during periods of strong offshore winds coincident with unusually dry vegetation enabled by anomalously warm conditions and late onset of autumn precipitation. In this study, we quantify observed changes in the occurrence and magnitude of meteorological factors that enable extreme autumn wildfires in California, and use climate model simulations to ascertain whether these changes are attributable to human-caused climate change. We show that state-wide increases in autumn temperature (∼1 °C) and decreases in autumn precipitation (∼30%) over the past four decades have contributed to increases in aggregate fire weather indices (+20%). As a result, the observed frequency of autumn days with extreme (95th percentile) fire weather—which we show are preferentially associated with extreme autumn wildfires—has more than doubled in California since the early 1980s. We further find an increase in the climate model-estimated probability of these extreme autumn conditions since ∼1950, including a long-term trend toward increased same-season co-occurrence of extreme fire weather conditions in northern and southern California. Our climate model analyses suggest that continued climate change will further amplify the number of days with extreme fire weather by the end of this century, though a pathway consistent with the UN Paris commitments would substantially curb that increase. Given the acute societal impacts of extreme autumn wildfires in recent years, our findings have critical relevance for ongoing efforts to manage wildfire risks in California and other regions.

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.

Abstract Efforts to meaningfully quantify the changes in coastal compound surge- and rainfall-driven flooding hazard associated with tropical cyclones (TCs) and extratropical cyclones (ETCs) in a warming climate have increased in recent years. Despite substantial progress, however, obtaining actionable details such as the spatially and temporally varying distribution and proximal causes of changing flooding hazard in cities remains a persistent challenge. Here, for the first time, physics-based hydrodynamic flood models driven by rainfall and storm surge simultaneously are used to estimate the magnitude and frequency of compound flooding events. We apply this to the particular case of New York City. We find that sea level rise (SLR) alone will increase the TC and ETC compound flooding hazard more significantly than changes in storm climatology as the climate warms. We also project that the probability of destructive Sandy-like compound flooding will increase by up to 5 times by the end of the century. Our results have strong implications for climate change adaptation in coastal communities.