• Energy Research

Exposure to cold spells is associated with mortality. However, little is known about the global mortality burden of cold spells.A three-stage meta-analytical method was used to estimate the global mortality burden associated with cold spells by means of a time series dataset of 1960 locations across 59 countries (or regions). First, we fitted the location-specific, cold spell-related mortality associations using a quasi-Poisson regression with a distributed lag non-linear model with a lag period of up to 21 days. Second, we built a multivariate meta-regression model between location-specific associations and seven predictors. Finally, we predicted the global grid-specific cold spell-related mortality associations during 2000-19 using the fitted meta-regression model and the yearly grid-specific meta-predictors. We calculated the annual excess deaths, excess death ratio (excess deaths per 1000 deaths), and excess death rate (excess deaths per 100 000 population) due to cold spells for each grid across the world.Globally, 205 932 (95% empirical CI [eCI] 162 692-250 337) excess deaths, representing 3·81 (95% eCI 2·93-4·71) excess deaths per 1000 deaths (excess death ratio), and 3·03 (2·33-3·75) excess deaths per 100 000 population (excess death rate) were associated with cold spells per year between 2000 and 2019. The annual average global excess death ratio in 2016-19 increased by 0·12 percentage points and the excess death rate in 2016-19 increased by 0·18 percentage points, compared with those in 2000-03. The mortality burden varied geographically. The excess death ratio and rate were highest in Europe, whereas these indicators were lowest in Africa. Temperate climates had higher excess death ratio and rate associated with cold spells than other climate zones.Cold spells are associated with substantial mortality burden around the world with geographically varying patterns. Although the number of cold spells has on average been decreasing since year 2000, the public health threat of cold spells remains substantial. The findings indicate an urgency of taking local and regional measures to protect the public from the mortality burdens of cold spells.Australian Research Council, Australian National Health and Medical Research Council, EU's Horizon 2020 Project Exhaustion.

AbstractOlder adults are generally amongst the most vulnerable to heat and cold. While temperature-related health impacts are projected to increase with global warming, the influence of population aging on these trends remains unclear. Here we show that at 1.5 °C, 2 °C, and 3 °C of global warming, heat-related mortality in 800 locations across 50 countries/areas will increase by 0.5%, 1.0%, and 2.5%, respectively; among which 1 in 5 to 1 in 4 heat-related deaths can be attributed to population aging. Despite a projected decrease in cold-related mortality due to progressive warming alone, population aging will mostly counteract this trend, leading to a net increase in cold-related mortality by 0.1%–0.4% at 1.5–3 °C global warming. Our findings indicate that population aging constitutes a crucial driver for future heat- and cold-related deaths, with increasing mortality burden for both heat and cold due to the aging population.

L'augmentation du risque de mortalité est associée à une variabilité de la température à court terme. Cependant, à notre connaissance, il n'y a pas eu d'évaluation complète de la charge de mortalité liée à la variabilité de la température dans le monde. Dans cette étude, en utilisant les données du MCC Collaborative Research Network, nous avons d'abord exploré l'association entre la variabilité de la température et la mortalité dans 43 pays ou régions. Ensuite, pour fournir une image plus complète de la charge mondiale de mortalité associée à la variabilité de la température, des données de température maillées mondiales avec une résolution de 0,5° ×0,5° ont été utilisées pour évaluer la charge de mortalité liée à la variabilité de la température aux niveaux mondial, régional et national. En outre, les tendances temporelles de la charge de mortalité liée à la variabilité de la température ont également été explorées à partir de 2000-19. Dans cette étude de modélisation, nous avons appliqué une approche méta-analytique en trois étapes pour évaluer la charge de mortalité liée à la variabilité de la température mondiale à une résolution spatiale de 0,5° ×0,5° à partir de 2000-19. La variabilité de la température a été calculée comme l'écart-type de la moyenne des températures minimales et maximales des mêmes jours et des jours précédents. Nous avons d'abord obtenu des associations de mortalité liées à la variabilité de la température spécifiques à l'emplacement sur la base d'une série temporelle quotidienne de 750 emplacements du Multi-country Multi-city Collaborative Research Network. Nous avons ensuite construit un modèle de méta-régression multivariable avec cinq prédicteurs pour estimer les associations de mortalité liées à la variabilité de la température spécifique à la grille à travers le monde. Enfin, le pourcentage d'excès de mortalité et le taux de surmortalité ont été calculés pour quantifier la charge de mortalité liée à la variabilité de la température et pour explorer davantage sa tendance temporelle sur deux décennies. Une tendance croissante de la variabilité de la température a été identifiée au niveau mondial de 2000 à 2019. À l'échelle mondiale, 1 753 392 décès (IC à 95 % 1 159 901-2 357 718) ont été associés à la variabilité de la température par an, représentant 3·4 % (2·2-4·6) de tous les décès. La plupart de l'Asie, de l'Australie et de la Nouvelle-Zélande présentaient un pourcentage de surmortalité plus élevé que la moyenne mondiale. À l'échelle mondiale, le pourcentage d'excès de mortalité a augmenté d'environ 4·6 % (3·7-5·3) par décennie. La plus forte augmentation s'est produite en Australie et en Nouvelle-Zélande (7,3 %, ICà 95 % 4,3-10,4), suivie de l'Europe (4,4 %, 2,2-5,6) et de l'Afrique (3,3,1,9-4,6). Globalement, une charge de mortalité substantielle a été associée à la variabilité de la température, montrant une hétérogénéité géographique et une tendance temporelle légèrement croissante. Nos résultats pourraient aider à sensibiliser le public et à améliorer la compréhension des impacts sur la santé de la variabilité de la température.Australian Research Council, Australian National Health & Medical Research Council. El aumento del riesgo de mortalidad se asocia con la variabilidad de la temperatura a corto plazo. Sin embargo, hasta donde sabemos, no ha habido una evaluación exhaustiva de la carga de mortalidad relacionada con la variabilidad de la temperatura en todo el mundo. En este estudio, utilizando datos de la Red de Investigación Colaborativa de MCC, primero exploramos la asociación entre la variabilidad de la temperatura y la mortalidad en 43 países o regiones. Luego, para proporcionar una imagen más completa de la carga global de mortalidad asociada con la variabilidad de la temperatura, se utilizaron datos de temperatura cuadriculados globales con una resolución de 0·5° × 0·5° para evaluar la carga de mortalidad relacionada con la variabilidad de la temperatura a nivel mundial, regional y nacional. Además, también se exploraron las tendencias temporales en la carga de mortalidad relacionada con la variabilidad de la temperatura desde 2000-19. En este estudio de modelado, aplicamos un enfoque metaanalítico de tres etapas para evaluar la carga de mortalidad relacionada con la variabilidad de la temperatura global a una resolución espacial de 0·5° × 0·5° desde 2000-19. La variabilidad de temperatura se calculó como la DE de la media de las temperaturas mínimas y máximas del mismo día y de los días anteriores. Primero obtuvimos asociaciones de mortalidad relacionadas con la variabilidad de temperatura específicas de la ubicación basadas en una serie temporal diaria de 750 ubicaciones de la Red de Investigación Colaborativa Multinacional y Multinacional. Posteriormente, construimos un modelo de metarregresión multivariable con cinco predictores para estimar las asociaciones de mortalidad relacionadas con la variabilidad de temperatura específicas de la cuadrícula en todo el mundo. Finalmente, se calculó el exceso porcentual de mortalidad y la tasa de mortalidad excesiva para cuantificar la carga de mortalidad relacionada con la variabilidad de la temperatura y para explorar más a fondo su tendencia temporal durante dos décadas. Se identificó una tendencia creciente en la variabilidad de la temperatura a nivel mundial de 2000 a 2019. A nivel mundial, 1 753 392 muertes (IC 95% 1 159 901-2 357 718) se asociaron con la variabilidad de la temperatura por año, lo que representa el 3·4% (2·2-4·6) de todas las muertes. Se observó que la mayor parte de Asia, Australia y Nueva Zelanda tenían un exceso porcentual de mortalidad mayor que la media mundial. A nivel mundial, el porcentaje de exceso de mortalidad aumentó en aproximadamente un 4,6% (3,7-5,3) por década. El mayor aumento se produjo en Australia y Nueva Zelanda (7·3%, IC 95% 4·3-10·4), seguido de Europa (4·4%, 2 · 2-5·6) y África (3·3, 1 · 9-4·6). A nivel mundial, una carga de mortalidad sustancial se asoció con la variabilidad de la temperatura, mostrando heterogeneidad geográfica y una tendencia temporal ligeramente creciente. Nuestros hallazgos podrían ayudar a aumentar la conciencia pública y mejorar la comprensión de los impactos en la salud de la variabilidad de la temperatura. Consejo Australiano de Investigación, Consejo Nacional Australiano de Investigación Médica y de Salud. Increased mortality risk is associated with short-term temperature variability. However, to our knowledge, there has been no comprehensive assessment of the temperature variability-related mortality burden worldwide. In this study, using data from the MCC Collaborative Research Network, we first explored the association between temperature variability and mortality across 43 countries or regions. Then, to provide a more comprehensive picture of the global burden of mortality associated with temperature variability, global gridded temperature data with a resolution of 0·5° × 0·5° were used to assess the temperature variability-related mortality burden at the global, regional, and national levels. Furthermore, temporal trends in temperature variability-related mortality burden were also explored from 2000-19.In this modelling study, we applied a three-stage meta-analytical approach to assess the global temperature variability-related mortality burden at a spatial resolution of 0·5° × 0·5° from 2000-19. Temperature variability was calculated as the SD of the average of the same and previous days' minimum and maximum temperatures. We first obtained location-specific temperature variability related-mortality associations based on a daily time series of 750 locations from the Multi-country Multi-city Collaborative Research Network. We subsequently constructed a multivariable meta-regression model with five predictors to estimate grid-specific temperature variability related-mortality associations across the globe. Finally, percentage excess in mortality and excess mortality rate were calculated to quantify the temperature variability-related mortality burden and to further explore its temporal trend over two decades.An increasing trend in temperature variability was identified at the global level from 2000 to 2019. Globally, 1 753 392 deaths (95% CI 1 159 901-2 357 718) were associated with temperature variability per year, accounting for 3·4% (2·2-4·6) of all deaths. Most of Asia, Australia, and New Zealand were observed to have a higher percentage excess in mortality than the global mean. Globally, the percentage excess in mortality increased by about 4·6% (3·7-5·3) per decade. The largest increase occurred in Australia and New Zealand (7·3%, 95% CI 4·3-10·4), followed by Europe (4·4%, 2·2-5·6) and Africa (3·3, 1·9-4·6).Globally, a substantial mortality burden was associated with temperature variability, showing geographical heterogeneity and a slightly increasing temporal trend. Our findings could assist in raising public awareness and improving the understanding of the health impacts of temperature variability.Australian Research Council, Australian National Health & Medical Research Council. ترتبط زيادة خطر الوفاة بتقلب درجة الحرارة على المدى القصير. ومع ذلك، على حد علمنا، لم يكن هناك تقييم شامل لعبء الوفيات المرتبطة بتقلب درجة الحرارة في جميع أنحاء العالم. في هذه الدراسة، باستخدام بيانات من شبكة البحوث التعاونية لمؤسسة تحدي الألفية، استكشفنا أولاً العلاقة بين تقلب درجة الحرارة والوفيات عبر 43 دولة أو منطقة. بعد ذلك، لتوفير صورة أكثر شمولاً للعبء العالمي للوفيات المرتبطة بتقلب درجة الحرارة، تم استخدام بيانات درجة الحرارة العالمية الشبكية بدقة 0·5° × 0·5° لتقييم عبء الوفيات المرتبط بتقلب درجة الحرارة على المستويات العالمية والإقليمية والوطنية. علاوة على ذلك، تم أيضًا استكشاف الاتجاهات الزمنية في عبء الوفيات المرتبط بتقلب درجة الحرارة من 2000-19. في دراسة النمذجة هذه، طبقنا نهجًا تحليليًا تلويًا من ثلاث مراحل لتقييم عبء الوفيات المرتبط بتقلب درجة الحرارة العالمية بدقة مكانية قدرها 0·5° × 0·5° من 2000-19. تم حساب تقلب درجة الحرارة على أنه SD لمتوسط نفس درجات الحرارة الدنيا والقصوى للأيام السابقة. حصلنا أولاً على ارتباطات الوفيات المرتبطة بتقلبات درجات الحرارة الخاصة بالموقع بناءً على سلسلة زمنية يومية تضم 750 موقعًا من شبكة الأبحاث التعاونية متعددة المدن. قمنا بعد ذلك ببناء نموذج ميتا انحدار متعدد المتغيرات مع خمسة تنبؤات لتقدير التقلبات في درجات الحرارة الخاصة بالشبكة والارتباطات المرتبطة بالوفيات في جميع أنحاء العالم. أخيرًا، تم حساب النسبة المئوية للزيادة في معدل الوفيات ومعدل الوفيات الزائد لتحديد عبء الوفيات المرتبط بتقلب درجة الحرارة ولمواصلة استكشاف اتجاهه الزمني على مدى عقدين من الزمن. تم تحديد اتجاه متزايد في تقلب درجة الحرارة على المستوى العالمي من عام 2000 إلى عام 2019. على الصعيد العالمي، ارتبطت 1،753،392 حالة وفاة (95 ٪ CI 1،159،901-2،357،718) بتقلب درجة الحرارة سنويًا، وهو ما يمثل 3·4 ٪ (2·2-4·6) من جميع الوفيات. ولوحظ أن معظم آسيا وأستراليا ونيوزيلندا لديها نسبة مئوية أعلى من الزيادة في الوفيات من المتوسط العالمي. على الصعيد العالمي، زادت النسبة المئوية للزيادة في الوفيات بنحو 4.6٪(3.7-5.3) لكل عقد. حدثت أكبر زيادة في أستراليا ونيوزيلندا (7·3 ٪، 95 ٪ CI 4·3-10·4)، تليها أوروبا (4· 4 ٪، 2·2-5·6) وأفريقيا (3·3، 1 · 9-4·6). على الصعيد العالمي، ارتبط عبء الوفيات الكبير بتقلب درجة الحرارة، مما يدل على عدم التجانس الجغرافي والاتجاه الزمني المتزايد قليلاً. يمكن أن تساعد النتائج التي توصلنا إليها في زيادة الوعي العام وتحسين فهم الآثار الصحية لتقلب درجة الحرارة. مجلس البحوث الأسترالي، المجلس الوطني الأسترالي للبحوث الصحية والطبية.

BACKGROUND Climate change can directly impact temperature-related excess deaths and might subsequently change the seasonal variation in mortality. In this study, we aimed to provide a systematic and comprehensive assessment of potential future changes in the seasonal variation, or seasonality, of mortality across different climate zones. METHODS In this modelling study, we collected daily time series of mean temperature and mortality (all causes or non-external causes only) via the Multi-Country Multi-City Collaborative (MCC) Research Network. These data were collected during overlapping periods, spanning from Jan 1, 1969 to Dec 31, 2020. We projected daily mortality from Jan 1, 2000 to Dec 31, 2099, under four climate change scenarios corresponding to increasing emissions (Shared Socioeconomic Pathways [SSP] scenarios SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). We compared the seasonality in projected mortality between decades by its shape, timings (the day-of-year) of minimum (trough) and maximum (peak) mortality, and sizes (peak-to-trough ratio and attributable fraction). Attributable fraction was used to measure the burden of seasonality of mortality. The results were summarised by climate zones. FINDINGS The MCC dataset included 126 809 537 deaths from 707 locations within 43 countries or areas. After excluding the only two polar locations (both high-altitude locations in Peru) from climatic zone assessments, we analysed 126 766 164 deaths in 705 locations aggregated in four climate zones (tropical, arid, temperate, and continental). From the 2000s to the 2090s, our projections showed an increase in mortality during the warm seasons and a decrease in mortality during the cold seasons, albeit with mortality remaining high during the cold seasons, under all four SSP scenarios in the arid, temperate, and continental zones. The magnitude of this changing pattern was more pronounced under the high-emission scenarios (SSP3-7.0 and SSP5-8.5), substantially altering the shape of seasonality of mortality and, under the highest emission scenario (SSP5-8.5), shifting the mortality peak from cold seasons to warm seasons in arid, temperate, and continental zones, and increasing the size of seasonality in all zones except the arid zone by the end of the century. In the 2090s compared with the 2000s, the change in peak-to-trough ratio (relative scale) ranged from 0·96 to 1·11, and the change in attributable fraction ranged from 0·002% to 0·06% under the SSP5-8.5 (highest emission) scenario. INTERPRETATION A warming climate can substantially change the seasonality of mortality in the future. Our projections suggest that health-care systems should consider preparing for a potentially increased demand during warm seasons and sustained high demand during cold seasons, particularly in regions characterised by arid, temperate, and continental climates. FUNDING The Environment Research and Technology Development Fund of the Environmental Restoration and Conservation Agency, provided by the Ministry of the Environment of Japan.

Background: Cardiovascular disease is the leading cause of death worldwide. Existing studies on the association between temperatures and cardiovascular deaths have been limited in geographic zones and have generally considered associations with total cardiovascular deaths rather than cause-specific cardiovascular deaths. Methods: We used unified data collection protocols within the Multi-Country Multi-City Collaborative Network to assemble a database of daily counts of specific cardiovascular causes of death from 567 cities in 27 countries across 5 continents in overlapping periods ranging from 1979 to 2019. City-specific daily ambient temperatures were obtained from weather stations and climate reanalysis models. To investigate cardiovascular mortality associations with extreme hot and cold temperatures, we fit case-crossover models in each city and then used a mixed-effects meta-analytic framework to pool individual city estimates. Extreme temperature percentiles were compared with the minimum mortality temperature in each location. Excess deaths were calculated for a range of extreme temperature days. Results: The analyses included deaths from any cardiovascular cause (32 154 935), ischemic heart disease (11 745 880), stroke (9 351 312), heart failure (3 673 723), and arrhythmia (670 859). At extreme temperature percentiles, heat (99th percentile) and cold (1st percentile) were associated with higher risk of dying from any cardiovascular cause, ischemic heart disease, stroke, and heart failure as compared to the minimum mortality temperature, which is the temperature associated with least mortality. Across a range of extreme temperatures, hot days (above 97.5th percentile) and cold days (below 2.5th percentile) accounted for 2.2 (95% empirical CI [eCI], 2.1–2.3) and 9.1 (95% eCI, 8.9–9.2) excess deaths for every 1000 cardiovascular deaths, respectively. Heart failure was associated with the highest excess deaths proportion from extreme hot and cold days with 2.6 (95% eCI, 2.4–2.8) and 12.8 (95% eCI, 12.2–13.1) for every 1000 heart failure deaths, respectively. Conclusions: Across a large, multinational sample, exposure to extreme hot and cold temperatures was associated with a greater risk of mortality from multiple common cardiovascular conditions. The intersections between extreme temperatures and cardiovascular health need to be thoroughly characterized in the present day—and especially under a changing climate.

BACKGROUND Exposure to cold or hot temperatures is associated with premature deaths. We aimed to evaluate the global, regional, and national mortality burden associated with non-optimal ambient temperatures. METHODS In this modelling study, we collected time-series data on mortality and ambient temperatures from 750 locations in 43 countries and five meta-predictors at a grid size of 0·5° × 0·5° across the globe. A three-stage analysis strategy was used. First, the temperature-mortality association was fitted for each location by use of a time-series regression. Second, a multivariate meta-regression model was built between location-specific estimates and meta-predictors. Finally, the grid-specific temperature-mortality association between 2000 and 2019 was predicted by use of the fitted meta-regression and the grid-specific meta-predictors. Excess deaths due to non-optimal temperatures, the ratio between annual excess deaths and all deaths of a year (the excess death ratio), and the death rate per 100 000 residents were then calculated for each grid across the world. Grids were divided according to regional groupings of the UN Statistics Division. FINDINGS Globally, 5 083 173 deaths (95% empirical CI [eCI] 4 087 967-5 965 520) were associated with non-optimal temperatures per year, accounting for 9·43% (95% eCI 7·58-11·07) of all deaths (8·52% [6·19-10·47] were cold-related and 0·91% [0·56-1·36] were heat-related). There were 74 temperature-related excess deaths per 100 000 residents (95% eCI 60-87). The mortality burden varied geographically. Of all excess deaths, 2 617 322 (51·49%) occurred in Asia. Eastern Europe had the highest heat-related excess death rate and Sub-Saharan Africa had the highest cold-related excess death rate. From 2000-03 to 2016-19, the global cold-related excess death ratio changed by -0·51 percentage points (95% eCI -0·61 to -0·42) and the global heat-related excess death ratio increased by 0·21 percentage points (0·13-0·31), leading to a net reduction in the overall ratio. The largest decline in overall excess death ratio occurred in South-eastern Asia, whereas excess death ratio fluctuated in Southern Asia and Europe. INTERPRETATION Non-optimal temperatures are associated with a substantial mortality burden, which varies spatiotemporally. Our findings will benefit international, national, and local communities in developing preparedness and prevention strategies to reduce weather-related impacts immediately and under climate change scenarios. FUNDING Australian Research Council and the Australian National Health and Medical Research Council.