Abstract
Background:
Climate change significantly impacts health, particularly for individuals aged 65 and older, increasing heat-related illnesses and mortality. Understanding this burden is vital for public health planning.
Methods:
This study analyzes data from the Global Burden of Disease (GBD) Study 2021, focusing on deaths, disability-adjusted life years (DALYs), and age-standardized ratios related to high-temperature exposure in individuals aged 65+ across 204 nations and territories. It examines trends from 1990 to 2021, assesses health inequities using measures like the Inequality Slope Index and Concentration Index, and projects future trends using a Bayesian Age-Period-Cohort (BAPC) model.
Results:
In 2021, there were 247,098 heat-related deaths globally among those aged 65+, with an age-standardized mortality rate (ASMR) increase from 26.3 to 27.1 per 100,000 (annual average percentage change (AAPC): 0.22). Aggregate DALYs reached 3,986,215, with the age-standardized DALYs rate (ASDR) rising from 419.6 to 526.7 per 100,000. South Asia and East Asia experienced higher burdens, while Oceania and Western Australia had lower rates. Lower-middle Socio-demographic Index (SDI) regions faced greater burdens, with absolute inequality increasing and relative inequality slightly declining. Non-communicable diseases (NCDs), such as ischemic heart disease and stroke, accounted for a significant proportion of heat-related deaths and DALYs, with upward trends. Projections indicate continued increases in deaths and DALYs by 2050.
Conclusions:
This study highlights the growing global burden of high-temperature exposure on older adults, emphasizing regional disparities and the dominance of NCDs. These findings underscore the need for targeted public health strategies to address climate-related health risks in vulnerable populations.
Introduction
The increasingly apparent effects of climate change, particularly rising global temperatures, pose significant challenges to public health (The Lancet Infectious Diseases, 2023; Steg, 2023; Epstein and Yanovich, 2019). With continuous warming, the incidence and mortality rates of heatstroke have risen markedly (Vicedo-Cabrera et al., 2021). Studies show that between 2017 and 2021, the number of heat-related deaths among individuals aged 65 and older increased by 68% compared to the period from 2000 to 2004 (Romanello et al., 2022), surpassing the total deaths caused by all other natural disasters combined (McGeehin and Mirabelli, 2001). Over the past two decades, the heat-related mortality rate in this age group has increased by 53.7%, reaching 296,000 deaths in 2018 (Watts et al., 2021). As global temperatures continue to rise, the frequency and intensity of heatwaves are increasing, leading to a surge in heat-related illnesses, such as heatstroke, heat exhaustion, and exacerbations of chronic diseases (Kovats and Hajat, 2008). The World Health Organization (WHO) has identified extreme heat as a critical environmental health risk, particularly for older adults, who often have reduced physiological responses to heat and may face social isolation or limited access to cooling resources (World Health Organization, 2021).
The relationship between high temperature exposure and adverse health outcomes is complex and influenced by various socioeconomic factors, including education level, GDP, and urban population ratio (Zhang et al., 2019; Hu et al., 2019). High temperatures are strongly associated with increased morbidity and mortality worldwide, especially for all-cause mortality, cardiovascular diseases, and respiratory illnesses (Arbuthnott et al., 2020; Cheng et al., 2019). Research indicates that older adults are particularly vulnerable to the health impacts of high temperatures, experiencing higher hospitalization rates, increased mortality, and a greater overall disease burden (Luber and McGeehin, 2008). Given the ongoing effects of climate change, understanding the health impacts of high temperatures on this population is essential for developing effective public health strategies. Despite growing awareness, research on this topic remains limited, particularly in terms of comprehensive global assessments. Most existing studies are concentrated in developed regions such as East Asia, Europe, and North America, with a lack of comparative data across diverse geographic and economic settings (Arbuthnott et al., 2020; Cheng et al., 2019). This gap highlights the need for more inclusive, international research to better understand the global health impacts of high temperature exposure.
To address this gap, we conducted a global analysis using the Global Burden of Disease (GBD) 2021 study data to assess the disease burden associated with environmental high temperature exposure among individuals aged 65 and older from 1990 to 2021. The GBD study provides a comprehensive framework for evaluating the long-term health impacts of diseases and risk factors (Collaborators GDaI, 2020). GBD data indicate that older adults face substantial health risks from high temperature exposure, including heatstroke, cardiovascular and respiratory diseases, and mental health challenges, all of which can worsen during extreme heat events (Collaborators GDaI, 2020). This study aimed to examine global trends in high temperature exposure and its associated health impacts over the past three decades, with a focus on older adults, to inform targeted public health policies and interventions that can mitigate the effects of climate change.
Methods
Date source
GBD 2021 utilizes the latest epidemiological data and improved standardized methods to comprehensively assess health loss due to 371 diseases, injuries, and disabilities, as well as 87 risk factors across 204 countries and regions, differentiating by age and sex (Collaborators GDaI, 2024; Collaborators GLRIaAR, 2024). It integrates data from various sources with unique identifiers in GHDx. This study extracted data on deaths, DALYs, and corresponding age-standardized rates and 95% uncertainty intervals (UI) for high temperature-related deaths among individuals aged 65 and older from GBD 2021, with all rates reported per 100,000 people (Cao et al., 2023). Causes of death are categorized into four levels (Level I to Level IV). Level I causes include communicable diseases, maternal, neonatal, and nutritional disorders (CMNND), non-communicable diseases, and injuries. Level II causes represent specific classifications of Level I causes; for example, cardiovascular diseases (Level II) fall under non-communicable diseases (Level I), while stroke (Level III) is a specific cause under cardiovascular diseases (Level II), and ischemic stroke (Level IV) is a sub-cause of stroke (Level III). This study primarily discusses the burden from Level I to Level III, incorporating 17 specific causes of disease (Level III) as outcomes related to high temperatures. Additionally, the study employs the SDI to quantify the level of social demographic development in a country or region, categorizing SDI into five levels: low, low-middle, middle, high-middle, and high (Collaborators GAM, 2021). This research adheres to the guidelines set forth by the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER; Stevens et al., 2016).
Definition of high temperature exposure
Estimates of high temperature exposure at various locations in the GBD study are based on data sourced and computed from the European Center for Medium-Range Weather Forecasts (ECMWF; Song et al., 2022). The GBD research defines the minimum value of the average exposure-response curve for specific diseases as the theoretical minimum risk exposure level (TMREL; Collaborators GL, 2022). Due to differences in how high temperature exposure affects various locations, diseases, and years, the TMREL for high temperatures in the GBD study is not a one-size-fits-all measure. Rather, it reflects the temperature linked to the lowest mortality risk for all diseases of the same cause within the same year and area. High temperature is characterized as an environmental temperature that surpasses the TMREL (Cui et al., 2023). Additional details on the data sources for high temperature exposure are available at http://ghdx.healthata.org/gbd-2021/data-input-sources.
Data analysis
This study utilizes age-standardized rates derived from GBD world population age estimates as a reference, following the approach outlined by Ahmad et al. (2001). Direct standardization produces an age-adjusted rate, which serves as a weighted average of age-specific rates. The weights are intended to represent the relative age distribution. This composite rate reflects the anticipated number of events within a population characterized by a similar age distribution. The direct age-standardized rate is determined using the formula: .
Where, ai and wi represent the specific age rates and the number of individuals in the corresponding age group of the selected reference population (or weights), where i indicates the i-th age group. To assess temporal trends in incidence rates (or other outcome measures), we employ the AAPC, which aggregates trends over a specified timeframe. An AAPC exhibiting a 95% confidence interval (CI) that is either greater than or less than 0, alongside a p-value < 0.05, signifies an upward or downward trend during that period (Clegg et al., 2009). The AAPC is especially advantageous for capturing rate changes when such changes fluctuate over time, as it conveys the geometric mean of annual percent changes across multiple intervals. For AAPC calculation, we initially fit a segmented regression model to the annual growth rates of the outcome variable. These models facilitate the estimation of distinct linear trends within specified segments, with breakpoints identified through a likelihood maximization iterative method. The breakpoints signal shifts in trends and are determined empirically using the “segmented” package in R. Furthermore, we generated scatter plots to examine the relationships among age-standardized mortality rates, DALY rates, DALY rates associated with high temperature-related diseases, and the quintiles of the SDI. All statistical analyses were performed using R statistical software (version 4.2.0), with statistical significance assessed at a p-value threshold of < 0.05.
Cross-country inequality analysis
This study uses the inequality slope index (SII) and concentration index defined by the WHO to assess absolute and relative inequalities in high-temperature exposure among those aged 65 and older (World Health Organization, 2013). These metrics quantify health disparities across countries and regions. The SII is calculated via DALYs regression analysis using midpoints from SDI-sorted cumulative population distribution. We analyzed data from 204 countries and regions from 1990 to 2021 to evaluate health inequality changes. To enhance accuracy, robust regression models (rlm) replaced ordinary linear regression models (lm) to reduce outlier sensitivity and bias. The concentration index is computed by correlating cumulative death and DALY proportions with SDI-sorted cumulative population distribution and integrating the Lorenz curve area.
Frontier analysis and decomposition analysis
To evaluate the link between high-temperature exposure disease burden and SDI in those 65 and older, we used frontier analysis. Based on ASMR and ASDR, this analysis clarifies the non-linear SDI-disease burden relationship, highlighting high-temperature exposure burden drivers. It emphasizes the minimum ASMR and ASDR for each region's development level, quantifying the gap between current and potential minimum burdens. We used locally weighted regression (LOESS) and local polynomial regression with different smoothing spans (0.3, 0.4, 0.5) for a smoothed frontier line. To confirm analysis robustness, 1,000 bootstrap samples were done, and average ASMR and ASDR for each SDI were calculated. We evaluated improvement potential by assessing the 2021 ASMR and ASDR distance from the frontier line in each country or region (Xie et al., 2018).
We used the Das Gupta decomposition method to analyze high-temperature exposure disease burden changes in those 65 and older from 1990 to 2021 (Das Gupta, 1994). The method attributes changes to aging, population growth, and epidemiological shifts, providing a framework to analyze key burden-change drivers. This helps us understand how demographic and epidemiological transitions affect disease burden trends. Among these, epidemiological change refers to the net effect on population health risk after accounting for population size and age structure. It mainly includes temporal changes in environmental temperature exposure, population susceptibility, accessibility of health care services, and other relevant factors, and is used to reflect the true variation in disease risk. Different from linear regression, decomposition analysis independently evaluates each factor's impact on disease burden changes. Analyzing these trends gives clearer insights into the global disease burden drivers related to high-temperature exposure for the elderly.
BAPC model prediction
To improve public health policies and resource allocation, we also forecasted the burden of high temperature exposure in adults aged 65 years and older for the next decade. Using the BAPC package in R, we projected the changes in the global burden of high temperature exposure in adults aged 65 years and older from 2022 to 2050. Unlike traditional age-period-cohort (APC) models, which face identification challenges due to the interdependence of age, period, and cohort effects, the BAPC model employs a Bayesian framework (Chen et al., 2011). This approach treats unknown parameters as random variables with prior distributions, offering greater adaptability to data characteristics. Additionally, it incorporates extra parameters to account for data dispersion. By integrating prior knowledge about unknown parameters with sample data, the BAPC model estimates the posterior distribution of the parameters and performs inferences based on this. This Bayesian-based inference fundamentally differs from classical statistical methods, which infer population parameters solely from sample data. Specifically, the BAPC model assumes the prior distribution of the age effect as follows:
Given our focus on the incident cases for age group a over a future period t, the following equation can be applied:
Here, we introduce an independent random effect to adjust for overdispersion (Riebler and Held, 2017). Under the smoothing assumption, the BAPC model assumes the prior distribution of the period effect as follows:
Results
The death burden of the elderly aged 65 and above caused by high temperatures from 1990 to 2021 and its changing trend
In 2021, heat-related deaths among those aged 65+ reached 247,098 globally (95% UI: 146,767–376,025), up from 77,664 in 1990 (95% UI: 40,571–127,082). The ASMR rose from 26.3 to 33.6 per 100,000 (AAPC: 0.22, 95% CI: 0.03–0.40). South Asia had the highest number of heat-related deaths in the world, followed by East Asia, while Oceania and Australasia had the lowest number of heat-related deaths. North Africa and the Middle East had the highest ASMR related to heat, whereas Australasia and Western Europe had the lowest values of this indicator (Supplementary Table S1 and Supplementary Figure S1A). A total of 18 countries had a heat-related ASMR exceeding 150 per 100,000 population, and these countries were mainly distributed in Africa and the Middle East; among them, the United Arab Emirates, Iraq, and Mauritania ranked the top three in this indicator (Supplementary Table S1 and Figure 1A). Males experienced higher death numbers and rates (Supplementary Table S1 and Figure 2A). West Sub-Saharan Africa showed the highest increase (AAPC: 1.12, 95% CI: 0.26–1.80). By contrast, no statistically significant temporal changes were observed in Western Europe, Western Australia, high-income Asia Pacific, high-income North America, and East Asia (Supplementary Table S1 and Figure 1C).
Figure 1
Figure 2
The DALYs burden of the elderly aged 65 and above caused by high temperatures from 1990 to 2021 and its changing trend
In 2021, the total DALYs attributed to high temperatures among individuals aged 65 and older worldwide reached 3,986,215 (95% UI: 2,405,570–5,973,258), marking a substantial increase from 1,325,898 in 1990 (95% UI: 705,571–2,135,293). The global ASDR rose from 419.6 to 526.7 per 100,000. South Asia has the highest burden of heat-related DALYs, followed by East Asia, while Oceania and Australasia have the lowest. For the ASDR associated with high temperatures, West Sub-Saharan Africa ranks the highest, North Africa and the Middle East comes next, and the lowest values are observed in Australasia and Western Europe (Supplementary Table S2 and Supplementary Figure S1B). Nine countries, mostly in Africa and the Middle East, had ASDR above 5,000 per 100,000, with the United Arab Emirates, Iraq, and Mauritania (Supplementary Table S2 and Figure 1B). Males had higher DALYs and ASDR (Supplementary Table S2 and Figure 2B). The overall burden of disease from high temperatures varies greatly across regions, with most showing an upward trend. The most significant increase occurred in West Sub-Saharan Africa, followed by Central Asia and South Asia. In contrast, regions such as Western Europe, Western Australia, high-income Asia-Pacific, high-income North America, southern South America, and East Asia demonstrated a downward trend, with East Asia experiencing the largest decline, indicated by an AAPC of −3.83 (95% CI: −9.04 to 1.37; Supplementary Table S2 and Figure 1D).
Impact of SDI on the burden of high temperature-related diseases in the elderly aged 65 and above
From 1990 to 2021, heat-related deaths and DALYs among the elderly surged globally (Figure 2 and Supplementary Figure S2), with low-middle SDI regions peaking at 102,301 deaths (95% CI: 66,482–143,362) and 1,719,752 DALYs (95% CI: 1,120,285–2,406,654) in 2021 (Supplementary Tables S1, S2). This contrasts with high SDI regions, reporting the lowest counts at 15,902 deaths (95% CI: 6,679–26,869) and 231,111 DALYs (95% CI: 103,980–423,396). ASMR in low-middle SDI regions was 101.4 per 100,000 (95% CI: 65.7–142.1), and the ASDR was 1,577.2 per 100,000 (95% CI: 1,025.6–2,208.6), significantly higher than high SDI regions' rates of 7.1 per 100,000 (95% CI: 3.1–13.3) and 109.3 per 100,000 (95% CI: 49.8–198.6), respectively (Supplementary Tables S1, S2). Low-middle and low SDI regions showed the most significant increases in ASMR and ASDR, while high and middle-high SDI regions experienced more moderate growth (Supplementary Tables S1, S2 and Figure 2).
Inequality analysis, frontier analysis, and decomposition analysis of the disease burden due to high temperature exposure among adults aged 65 and above
Regarding high temperature exposure disease burden in the elderly, significant absolute and relative inequalities were linked to the SDI. Lower SDI regions had a heavier burden. The inequality slope index showed the ASMR gap between top and bottom SDI areas grew from −21.04 (95% CI: −27.78 to −14.29) in 1990 to −33.76 (95% CI: −43.57 to −23.94) in 2021. The concentration index dropped from −0.24 (95% CI: −0.42 to −0.07) in 1990 to −0.20 (95% CI: −0.38 to −0.03) in 2021. The ASDR gap increased from −343.18 (95% CI: −449.25 to −237.12) in 1990 to −542.44 (95% CI: −691.30 to −393.57) in 2021, and the DALYs concentration index decreased from −0.25 (95% CI: −0.43 to −0.08) in 1990 to −0.22 (95% CI: −0.39 to −0.05) in 2021. So, relative inequalities lessened, but absolute ones grew from 1990 – 2021 (Supplementary Table S3 and Supplementary Figure S3).
By analyzing 1990–2021 data, we evaluated the potential to reduce high temperature exposure disease burden in those 65 and older, focusing on ASMR and ASDR. Fifteen countries and regions, including low SDI ones like Mali and Niger and high SDI ones like the United Arab Emirates, and Saudi Arabia, had the greatest ASMR improvement potential. The same 15 regions also showed great ASDR improvement potential. Frontier analysis showed that low SDI countries like Niger managed disease well despite limited resources, while high SDI countries like the United Arab Emirates, Saudi Arabia, and Qatar still had much room for improvement (Figure 3).
Figure 3
This study employs a decomposition analysis method to assess the burden of disease indicators related to high temperature exposure among individuals aged 65 and older globally from 1990 to 2021, including ASMR and ASDR. It further explores the impacts of factors such as population aging, population growth, and epidemiological changes on these indicators. Epidemiological changes refer to the temporal variations in disease burden influenced by factors such as rising temperatures, improvements in exposure, and advancements in treatment capabilities. The results indicate a significant upward trend in the disease burden from heat exposure among the elderly worldwide, particularly pronounced in regions with low to middle SDI. Regarding ASMR, population growth, epidemiological changes, and population aging contributed 73.22%, 21.57%, and 5.22%, respectively. Notably, the impact of population growth is most significant across all SDI regions, especially in low-middle and middle SDI areas. The driving factors differ across SDI regions: in low, low-middle, and high-middle SDI areas, the influence of epidemiological changes surpasses that of population aging; whereas in middle SDI regions, the impact of population aging exceeds that of epidemiological changes. It is noteworthy that high SDI regions exhibit negative contributions from both epidemiological changes and population aging, indicating that these factors play a protective role against the increase in disease burden due to heat exposure. The driving factors for ASDR align closely with those observed for ASMR (Supplementary Table S4 and Figure 4).
Figure 4
Ranking and changing trend of disease burden in the elderly aged 65 and above caused by high temperature
In 2021, non-communicable diseases were responsible for 86% of deaths among individuals aged 65 and older due to high temperatures, whereas CMNND accounted for 12%. In terms of DALY attributable to high temperatures, non-communicable diseases represented 84%, with CMNND at 11%. Among various causes at the GBD3 level, ischemic heart disease (10.16, 95% UI: 1.13–24.52), stroke (7.60, 95% UI: 0.50–18.70), and chronic obstructive pulmonary disease (4.27, 95% UI: −0.94 to 11.94) had the highest mortality rates linked to high temperatures. The top three conditions in terms of DALY rates were also ischemic heart disease (157.22, 95% UI: 20.94–368.08), stroke (120.53, 95% UI: 12.13–290.09), and chronic obstructive pulmonary disease (64.95, 95% UI: −13.29 to 179.70), all showing an increase compared to 1990. Importantly, the burden of high temperatures varies by disease. Globally, the burden of non-communicable diseases attributed to high temperatures is increasing, while that of CMNND and injuries is decreasing (Supplementary Table S5 and Figure 5).
Figure 5
Forecast of disease burden due to high temperatures exposure among individuals aged 65 and older (2022–2050)
By 2050, it is projected that the burden of disease due to high temperature exposure among individuals aged 65 and older will increase globally. The estimated number of deaths is expected to reach 617,196 (95% UI: −685,869 to 1,920,262), resulting in an ASMR of 38.16 per 100,000 (95% UI: −42.41 to 118.74). Additionally, the number of DALYs is anticipated to rise to 9,603,112 (95% UI: −11,308,848 to 30,515,071), with an ASDR of 536.90 per 100,000 (95% UI: 119.67 to 954.12; Supplementary Table S6 and Supplementary Figure S4).
Discussion
This study presents the first systematic analysis of the health burden attributed to high temperatures among adults aged 65 years and older worldwide between 1990 and 2021. Specifically, it comprehensively examines the number of deaths, DALYs, and their corresponding age-standardized rates, while also exploring disparities across different regions, genders, SDI levels, and disease types. The notable increase in high temperature-related deaths and DALYs underscores that this issue has emerged as a major public health concern, which is likely associated with rising global temperatures driven by climate change (Watts et al., 2021). Furthermore, the upward trends in ASMR and ASDR further illustrate the growing adverse impacts of high temperatures on population health—particularly in regions lacking effective mitigation measures—consistent with findings from previous studies (Zhang et al., 2024; Song et al., 2021). Projections indicate a sharp rise in ASMR and ASDR among the elderly by 2050. Collectively, these results suggest that high-temperature-related health risks are escalating alongside global warming, presenting a pressing global public health challenge that demands immediate international attention and actionable interventions.
Regional distribution analysis reveals that South and East Asia bear a high burden of high temperature-related mortality and DALYs, which is likely attributable to dense populations, rapid urbanization, and inadequate infrastructure and medical resources (Cheng et al., 2019). In urban areas of developing countries, the urban heat island effect amplifies the impact on the elderly, whose vulnerability is further exacerbated by poor living conditions (Sera et al., 2019). Recently, South Asian countries such as India and Pakistan have been confronted with extreme heat events (Jain and Jain, 2022; Shepherd, 2022), whereas Oceania and Western Australia experience a lighter burden due to lower population density and superior socioeconomic development (Green et al., 2019). A notable upward trend in high temperature-related disease burden is observed in sub-Saharan West and Central Africa, as well as Central Asia. This trend is likely driven by limited economic development, which hinders investment in heat adaptation measures—such as air conditioning and healthcare services (Levy and Patz, 2015). Climate change may further increase the frequency and intensity of heat events in these regions (Watts et al., 2021). Conversely, Western Europe and Western Australia exhibit a downward trend in disease burden, a phenomenon attributed to high socioeconomic development that supports the implementation of heat warning systems and effective urban planning (Green et al., 2019). At the national level, elevated ASMR in countries including the United Arab Emirates, Iraq, and Mauritania merits attention. These regions face compounded challenges from extreme heat, water scarcity, and social instability, all of which adversely affect the availability and accessibility of public health resources (Pasquini et al., 2020). In terms of gender disparities, men have higher high temperature-related ASMR and ASDR, potentially due to their greater involvement in outdoor work, inherent physiological differences, and distinct social behaviors (Pasquini et al., 2020). Differences in social division of labor influenced by culture are an important reason: males are more likely to engage in high-temperature jobs such as construction, open-pit mining, and outdoor agriculture, with longer exposure time and higher intensity under extreme high temperatures (Jackson and Rosenberg, 2010; Li et al., 2017). At the same time, males have inherent disadvantages in their physiological structure, with weaker heat resistance and insufficient cardiovascular protection. In high-temperature environments, they are prone to increased blood viscosity and enhanced inflammatory responses, which in turn induce ischemic heart disease (IHD; Shaw et al., 2006; Wellons et al., 2012). In addition, the prevalence of underlying diseases such as cardiovascular diseases and diabetes, as well as the proportions of smoking and excessive drinking, are relatively higher in males (Huxley and Woodward, 2011). These factors further amplify the damage of high temperatures to the cardiovascular system and jointly increase the risk of high-temperature-related health problems in males.
Regions with medium to low Socio-Demographic Index (SDI) exhibit significantly higher rates of heat-related deaths, ASMR, DALYs, and ASDR compared to high-SDI regions. A negative correlation exists between SDI and heat-related mortality and DALY rates, which aligns with findings from previous research (Zhang et al., 2024). These medium-to-low SDI regions often suffer from weak infrastructure, limited medical resources, and insufficient heat mitigation measures, all of which increase residents' vulnerability to the health impacts of high-temperature environments (Levy and Patz, 2015). The growing trend in heat-related health burden in low-SDI regions is particularly concerning, as it is likely linked to high poverty levels and environmental vulnerabilities. These factors limit access to cooling resources and exacerbate adverse health outcomes as heat events become more frequent and intense (Pasquini et al., 2020; Ramin and McMichael, 2009). Conversely, while high-SDI and medium-high SDI regions show relatively stable growth in heat-related health burden, high-temperature-associated health issues remain a non-negligible concern.
Advanced economic development in these high and medium-high SDI regions enables improvements in urban planning, healthcare delivery, and public health infrastructure—all of which help mitigate the urban heat island effect and better address heat-related health challenges (Green et al., 2019). For instance, effective urban planning can expand green spaces and enhance ventilation, thereby reducing the heat island effect, while robust healthcare systems can more effectively respond to health issues associated with high temperatures (Sera et al., 2019). However, the ongoing impacts of global climate change may still increase the burden of heat-related diseases in these regions, highlighting the need for continuous monitoring and adaptive adjustments to existing strategies.
Health inequalities remain stark, with low-SDI regions bearing a heavier disease burden. This disparity is driven by widening gaps in ASMR and ASDR, inadequate infrastructure, and socioeconomic factors that impede their capacity to cope with high temperatures (Marmot, 2005). Nevertheless, with support from the international community and increased investment in the health sector in low-SDI regions, relative health inequalities have shown signs of improvement (World Health Organization, 2019). The study indicates that both low- and high-SDI countries have substantial room for improvement in addressing the high temperature-related disease burden. Low-SDI countries have successfully reduced this burden through community mobilization and cost-effective public health measures, which aligns with strategies proposed by Murray and Lopez (1996). In contrast, despite their abundant resources, high-SDI countries need to enhance the relevance of their urban planning and public health policies. McMichael et al. highlight the complex health impacts of climate change, urging high-SDI countries to incorporate considerations of how high temperatures affect the elderly into urban planning (McMichael et al., 2006). The disease burden caused by high-temperature exposure is on the rise globally and in all SDI regions, especially in low-and middle-SDI regions. Population growth is the main factor contributing to the ASMR and ASDR in all regions, which is related to global aging and the high population growth rate in low-and middle-SDI regions and is consistent with the relevant data of the United Nations (2019).
This study examines the main causes of disease burden related to high temperatures, finding that non-communicable diseases (NCDs) are the primary contributors to heat-related mortality and DALYs, with ischemic heart disease, stroke, and chronic obstructive pulmonary disease (COPD) on the rise. Conversely, the burden from CMNND and injuries is decreasing, reflecting several changes in global health trends. The prominence of NCDs is likely linked to population aging, as older adults may struggle to assess heat risks, increasing their vulnerability to heat-related health issues (Xi et al., 2024). Studies have shown that high temperature can affect the cardiovascular system through multiple pathophysiological pathways, such as altering sympathetic reactivity, activating the renin-angiotensin system, and inducing inflammation, thereby directly or indirectly leading to cardiovascular diseases (Giorgini et al., 2017). For chronic obstructive pulmonary disease (COPD), high temperature may exacerbate respiratory symptoms, impair lung function, and worsen the disease. Exposure to environmental high temperature is positively associated with COPD hospital admissions, especially in the late hot season (Lee and Kim, 2016). Elevated temperatures can exacerbate respiratory symptoms and reduce lung function in COPD patients, worsening their overall condition, and there is a positive correlation between exposure to high environmental temperatures and COPD-related hospitalizations, especially toward the end of the hot season (Zhao et al., 2019). The observed decline in the burden of CMNND can be linked to global progress in controlling infectious diseases, including vaccination efforts, enhanced sanitation, and improved access to healthcare services (Ouyang et al., 2020). However, CMNND continues to be a significant issue in certain areas, especially low SDI regions, where a lack of medical resources may impede further reductions in this burden (Ramin and McMichael, 2009). The decrease in injury-related burdens may be attributed to heightened safety awareness, better protective measures, and the successful enforcement of safety regulations in transportation and workplace settings (Willers et al., 2016). Nevertheless, the increasing trend of injury burden in high SDI regions requires scrutiny, potentially associated with complex environmental factors linked to urbanization, such as rising traffic volumes and infrastructure changes (Sera et al., 2019).
Predictive models indicate that from 2021 to 2050, individuals aged 65 and older will face significant health challenges due to diseases linked to heat exposure, leading to substantial increases in both mortality and DALYs. This pattern is further evidenced by rising ASMR and ASDR, highlighting the serious consequences of elevated temperatures for the health of older adults. Research has shown that rising temperatures significantly increase the risks of cerebrovascular diseases, cardiovascular diseases, diabetes, infectious diseases, heat-related illnesses, and respiratory diseases among older adults, and with ongoing climate change and an aging global population, these risks are expected to escalate (Bunker et al., 2016). Additionally, older adults are particularly susceptible to heat exposure, characterized by weakened heat stress responses and a higher prevalence of chronic conditions (Benmarhnia et al., 2015). To address this challenge, public health departments should implement effective measures, including establishing heatwave warning systems, improving urban planning to reduce the heat island effect, and enhancing health education for the elderly.
Our study provides valuable insights, but it also has several limitations. First, the GBD data are derived from national statistics reported by individual countries, which may be subject to biases in data collection and reporting. Second, in our regional and SDI-stratified analyses, we treated each region as a single unit, ignoring internal disparities. For instance, differences between countries or subgroups within South Asia, as well as heterogeneity in heat adaptation capacity and resource allocation across low- to middle-SDI regions, were not fully addressed. Third, we employed a BAPC model for trend projection. While this model can effectively infer future trends, it relies heavily on historical data and does not fully account for potential influencing factors such as future socioeconomic development, advances in medical technology, and policy interventions, which may affect the accuracy of the projections. Lastly, this study mainly focused on static comparisons of data from 1990 to 2021 and did not explore the impact of dynamic factors such as urbanization, population migration, medical technological progress, and changes in social policies on trends in high temperature-related disease burden.
Conclusion
Based on the analysis of GBD data, we conclude that heat-related deaths and DALYs among individuals aged 65 and older have significantly increased globally, with notable regional disparities. The SDI is negatively correlated with disease burden, and non-communicable diseases are predominant. This highlights the significant impact of high temperatures on global health and the varying vulnerabilities of different regions in addressing these threats. However, the study has limitations regarding data completeness, causal mechanisms, regional heterogeneity, and dynamic factors. Future research should aim to fill these gaps to better understand the relationship between heat and health, providing a basis for effective public health strategies. Additionally, efforts should be made to enhance prevention and control of heat-related illnesses, including health education, early identification, medical treatment capabilities, and improving social support and environmental adaptation measures to mitigate the impact on vulnerable populations.
Statements
Data availability statement
The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/Supplementary material.
Author contributions
WZ: Conceptualization, Data curation, Formal analysis, Methodology, Writing – original draft, Writing – review & editing. DZ: Data curation, Formal analysis, Methodology, Writing – original draft. HD: Data curation, Formal analysis, Writing – original draft. XS: Data curation, Software, Writing – original draft. XX: Data curation, Software, Writing – original draft. SZ: Software, Writing – review & editing. RS: Investigation, Validation, Visualization, Writing – review & editing. YX: Investigation, Project administration, Validation, Writing – review & editing. SJ: Validation, Writing – review & editing. YJ: Project administration, Writing – review & editing.
Funding
The author(s) declared that financial support was received for this work and/or its publication. This work was supported by the Science and Technology Project of Taizhou (23ywa47), the Medicines Health Research Fund of Zhejiang, China (2024ky1784), the National Key Research and Development Program of Zhejiang Province (2023C03083), and the Joint Fund of Zhejiang Provincial Natural Science Foundation of China under Grant No. LKLY25H200001.
Acknowledgments
The authors appreciate the work by the GBD 2021 collaborators and all who helped with this study.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Summary
Keywords
elderly, environmental impact, global disease burden, high temperature exposure, projection
Citation
Zhu W, Zhang D, Dai H, Shen X, Xia X, Zhang S, San R, Xu Y, Jin S and Jiang Y (2026) Global, regional, and national trends in disease burden attributable to high temperature exposure in adults aged 65 years and older from 1990 to 2021. Front. Clim. 8:1811293. doi: 10.3389/fclim.2026.1811293
Received
14 February 2026
Revised
04 April 2026
Accepted
30 April 2026
Published
21 May 2026
Volume
8 - 2026
Edited by
Adugna Woyessa, Ethiopian Public Health Institute, Ethiopia
Reviewed by
Goran Trbic, University of Banjaluka, Bosnia and Herzegovina
Weizhuo Yi, Anhui Medical University, China
Updates
Copyright
© 2026 Zhu, Zhang, Dai, Shen, Xia, Zhang, San, Xu, Jin and Jiang.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Yongpo Jiang, jyongpo8@163.com; Yinghe Xu, xuyh@enzemed.com; Shengwei Jin, jinshengwei69@163.com
† These authors have contributed equally to this work
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.