Focus on Health-Centred Climate Solutions

Climate change could lead to high economic burden for individuals (i.e. low income and high prices). While economic conditions are important determinants of climate change vulnerability, environmental epidemiological studies focus primarily on the direct impact of temperature on morbidity and mortality without accounting for climate-induced impacts on the economy. More integrated approaches are needed to provide comprehensive assessments of climate-induced direct and indirect impacts on health. This paper provides some perspectives on how epidemiological and economic impact assessments could be better integrated. We argue that accounting for the economic repercussions of climate change on people's health and, vice versa, the consequences of health effects on the economy could provide more realistic scenario projections and could be more useful for adaptation policy.

Previous studies have demonstrated an association between short-term exposure to ambient temperature and mortality. However, the long-term effects of elevated temperature and temperature variability on mortality have remained somewhat elusive in epidemiological studies. We conducted a comprehensive epidemiological study utilizing Chinese population census data from 2000 and 2010. Census-derived demographic and socioeconomic factors were paired with temperature data from the European Re-Analysis Land Dataset across 2823 counties. We employed a difference-in-difference approach to quantitatively examine the relationship between all-cause mortality and annual exposure to mean temperature and diurnal temperature range (DTR). Additionally, we evaluated the potential effects of socioeconomic and environmental covariate modifications on this relationship and calculated the attributable mortality. Lastly, we projected excess deaths attributable to annual temperature exposure under various shared socioeconomic pathways (SSPs, e.g. SSP126, SSP370, and SSP585). For each 1 °C rise in annual mean temperature and DTR, the mortality risk could increase by 6.12% (95% CI: 0.84%, 11.69%) and 7.72% (95% CI: 3.75%, 11.84%), respectively. Counties with high labor-force ratios and high NO₂ and O₃ concentrations appeared to be sensitive to the annual mean temperature and DTR. Climate warming from 2000 to 2010 may have resulted in 5.85 and 14.46 additional deaths per 10 000 people attributable to changes in annual mean temperature and DTR, respectively. The excess mortality related to changes in annual mean temperature and DTR is expected to increase in the future, with special attention warranted for long-term temperature changes in Southwest China. Our findings indicate that long-term mean temperature and DTR could significantly impact mortality rates. Given the spatial heterogeneity of increased mortality risk, the formulation of region-specific strategies to tackle climate change is crucial.

Concurrent compound heatwaves (CCHWs) occurring simultaneously in multiple regions in the Northern Hemisphere (NH) pose high-end risks to human health and global supply chains. Over the past decade, CCHWs related to human health have substantially increased in occurrence. However, the mechanisms of the CCHWs remain uncertain. This work has revealed a significant relationship between the variability of summer CCHWs in the NH and changes in quasi-stationary waves during 1979–2021, which can be attributed to the variation of summer snow cover over the western Tibetan Plateau (SC_WTP). Excessive SC_WTP causes diabatic cooling by modulating the surface energy budget and stimulating a tripolar Rossby wave source. The atmospheric response to the SC_WTP-driven disturbance manifests as a circumglobal circulation pattern, weakening the meridional temperature gradients and causing a 'double jet stream' in the NH. These changes modulate the phase, amplitude and proportion of quasi-stationary waves with wavenumbers 4–6, leading to an increase in CCHWs in the NH. In addition, population exposure to CCHWs reaches 4.91 billion person-day when the SC_WTP increases by one standard deviation. Our study highlights the significance of early warning and forecasting implications related to SC_WTP for CCHWs that impact human health within the context of climate change.

Health impact assessments have estimated substantial health co-benefits of climate change mitigation strategies due to reductions in air pollution in the US; however, few studies have considered children's health impacts and related equity implications. We estimated the potential health co-benefits to children related to improved air quality associated with various emissions cap and investment scenarios for the transportation sector in the Northeastern and Mid-Atlantic US proposed under the Transportation and Climate Initiative (TCI). We modeled changes in ambient fine particulate matter and nitrogen dioxide between 2022 and 2032 associated with on-road transportation sector emissions under nine hypothetical carbon dioxide (CO₂) emissions cap and investment scenarios proposed under TCI using the Community Multiscale Air Quality (CMAQ) model version 5.2. We estimated potential health co-benefits for adverse birth and pediatric respiratory and neurodevelopmental outcomes using an expanded version of the Environmental Benefits Mapping and Analysis Program, known as BenMAPR. We also examined impacts on pediatric asthma exacerbations across racial/ethnic groups. We found that health benefits to children increased as the CO₂ emission caps became more ambitious. The combination of the highest emissions cap (25%) and the investment scenario which prioritized public transit improvement (Diversified strategy) conferred the greatest children's health benefits for the majority of health outcomes considered, resulting in approximately \$82 million per year in economic savings. Assessment of the distribution of avoided pediatric asthma exacerbations showed benefits across all racial and ethnic groups, with a slightly greater reduction in cases for non-White populations. Decarbonization policies in the transportation sector in the Eastern US have the potential to provide important air quality and pediatric health co-benefits.

Extreme rainfall events could influence human health. However, the associations between extreme rainfall events and mortality remain rarely explored. Here, we conducted a time-series study using county-level mortality data in North Carolina during 2015–2018 to estimate the associations between extreme rainfall events and cause-specific mortality. We defined an extreme rainfall event as a day when a county's daily total precipitation exceeded the 95th percentile of daily rainfall measurements from all of North Carolina's counties during the study period. We employed a two-stage analysis where we first estimated the associations for each county and then used the estimates to obtain the state-wide associations by meta-analysis. Exposure to an extreme rainfall event was significantly associated with an increase in total, non-accidental, cardiovascular disease, respiratory disease, and external mortality by 2.24% (95% CI: 0.67%, 3.83%), 2.38% (95% CI: 0.76%, 4.03%), 3.60% (95% CI: 0.69%, 6.60%), 6.58% (95% CI: 1.59%, 11.82%), and 6.92% (95% CI: 1.28%, 12.86%), respectively. We did not find significant differences in the mortality risks within age, sex, or race groups or by seasonality. Our findings suggest that extreme rainfall events may trigger the risk of mortality, especially from non-accidental diseases such as respiratory mortality.

Extreme temperature exposure can have a considerable impact on the health of older adults. China, which has entered a deeply aging society, may be obviously threatened by extreme weather. Based on data obtained from the China Health and Retirement Longitudinal Study, we apply a panel fixed effect model to investigate the impact of extreme temperature on medical costs for older adults. The results reveal a U-shaped relationship between temperature and older adults' medical costs. Heterogeneity analysis indicates that medical costs for older adults in the South and older adults in rural areas are more significantly affected by low temperatures, mainly due to lower per capita heating facilities. Furthermore, the medical costs of older people with lower education levels are also more susceptible to temperature fluctuations. Our simulated prediction indicates that the medical costs of older adults in 2050 will be 2.7 trillion Chinese yuan under the RCP8.5 scenario, but can be reduced by 4.6% and 7.4% following RCP4.5 and RCP2.6 scenarios, respectively. Compared with base period, the medical costs of older adults in western provinces such as Guangxi and Sichuan will more than triple by 2050. Policymakers should prioritize addressing the health needs of these vulnerable groups and less developed regions with less adaptive capacity.

In 2021, the Japanese government changed the exposure indicator of the national heat-health warning system (HHWS) from air temperature (T_air) to Wet Bulb Globe Temperature (T_WBG), reflecting the growing concerns about the escalating humid heat stress. However, a clear validation of the advantages of using heat stress indicators (HSIs) that combine T_air and humidity in heat alerts and heat-health applications are still being explored. Here, by using the latest epidemiological data (2015–2019) before the COVID-19 pandemic, we examined the rationality of the revised HHWS for 47 prefectures in Japan. Specifically, we investigated the predictive power of different HSIs in modeling mortality and morbidity caused by different diseases (e.g. all causes, circulatory, respiratory, and heatstroke) and age groups. Our findings revealed substantial differences among the HSIs in identifying periods of intense heat stress, potentially leading to differences in the activation dates of the HHWS if various indicators were employed. While HSIs exhibited comparable performances in modeling daily mortality, our analysis demonstrates distinct advantages in using T_WBG for daily morbidity predictions, and the quasi-Akaike Information Criterion of T_WBG is much lower than the previously used T_air. The merits of T_WBG are consistent in modeling all causes, non-external, as well as heatstroke-related morbidity. Overall, this study underscores the practicality of incorporating HSIs in heat stress early warnings and provides critical insights for refining the HHWS to mitigate health impacts from heat stress under future climate change.

Increasing temperatures and more frequent heatwave events pose threats to population health, particularly in urban environments due to the urban heat island (UHI) effect. Greening, in particular planting trees, is widely discussed as a means of reducing heat exposure and associated mortality in cities. This study aims to use data from personal weather stations (PWS) across the Greater London Authority to understand how urban temperatures vary according to tree canopy coverage and estimate the heat-health impacts of London's urban trees. Data from Netatmo PWS from 2015–2022 were cleaned, combined with official Met Office temperatures, and spatially linked to tree canopy coverage and built environment data. A generalized additive model was used to predict daily average urban temperatures under different tree canopy coverage scenarios for historical and projected future summers, and subsequent health impacts estimated. Results show areas of London with higher canopy coverage have lower urban temperatures, with average maximum daytime temperatures 0.8 °C and minimum temperatures 2.0 °C lower in the top decile versus bottom decile canopy coverage during the 2022 heatwaves. We estimate that London's urban forest helped avoid 153 heat attributable deaths from 2015–2022 (including 16 excess deaths during the 2022 heatwaves), representing around 16% of UHI-related mortality. Increasing tree coverage 10% in-line with the London strategy would have reduced UHI-related mortality by a further 10%, while a maximal tree coverage would have reduced it 55%. By 2061–2080, under RCP8.5, we estimate that London's current tree planting strategy can help avoid an additional 23 heat-attributable deaths a year, with maximal coverage increasing this to 131. Substantial benefits would also be seen for carbon storage and sequestration. Results of this study support increasing urban tree coverage as part of a wider public health effort to mitigate high urban temperatures.

South Africa (SA) is highly vulnerable to the effects of drought on the environment, economy, and society. However, its effect on human health remains unclear. Understanding the mortality risk associated with different types of droughts in different population groups and by specific causes would help clarify the potential mechanisms involved. The study aims to comprehensively assess the effect of droughts of varying time scales on cause-specific mortality (all; infectious and parasitic; endocrine, nutritional, and metabolic; cardiovascular; respiratory) in SA (from 2009–2016) and identify more vulnerable profiles based on sex and age. We also evaluated the urbanicity and district-level socioeconomic deprivation as potential risk modifiers. We used a two-stage time-series study design, with the weekly standardized precipitation-evapotranspiration index (SPEI) calculated at 1, 6, 12, and 15 months of accumulation to identify droughts of different duration (SPEI1, 6, 12, 15, respectively). We applied a quasi-Poisson regression adjusted by mean temperature to assess the association between each type of drought and weekly mortality in all district municipalities of SA, and then pooled the estimates in a meta-regression model. We reported relative risks (RRs) for one unit increase of drought severity. Overall, we found a positive association between droughts (regardless the time scale) and all causes of death analyzed. The strongest associations were found for the drought events more prolonged (RR [95%CI]: 1.027 [1.018, 1.036] (SPEI1); 1.035 [1.021, 1.050] (SPEI6); 1.033 [1.008, 1.058] (SPEI12); 1.098 [1.068, 1.129] (SPEI15)) and respiratory mortality (RRs varied from 1.037 [1.021, 1.053] (SPEI1) to 1.189 [1.14, 1.241] (SPEI15)). An indication of greater vulnerability was found in younger adults for the shortest droughts, in older adults for medium-term and long-term droughts, and children for very long-term droughts. However, differences were not significant. Further evidence of the relevance of urbanicity and demographic and socioeconomic conditions as potential risk modifiers is needed.