Health effects and associated socio-economic costs of increasing temperatures and wildfires - A global assessment

Weather and Pollution Impact Our Health: When it gets extremely hot, it affects our health, and these effects are not independent of other factors affecting public health. The most significant environmental risk to our health today is air pollution from emissions both outdoors and indoors. Research shows that when high temperatures are combined with air pollution, it becomes even more harmful to our health. High temperatures in themselves can increase air pollution. Especially when it's very hot and dry, the risk of forest fires increases. These fires can lead to significant air pollution. With climate change, we expect periods of extreme heat and drought to become more common, posing a serious threat to our health. The HEATCOST Project: The HEATCOST project aims to understand how health issues related to extreme heat and air pollution (especially from forest fires) may change in the future. It also examines how these health issues may vary globally and what measures can reduce them. The project takes a global perspective, identifying areas and groups of people most vulnerable. We use well-known scenarios for economic growth, emissions, climate change, demographic changes, urbanization, and health status. Measuring Health Impact: To understand how extreme heat affects our health, we use different indicators called Heat Stress Indicators (HSI). These help us assess trends in the health impact of extreme heat relative to the global average temperature, especially in densely populated areas. We find that the levels of such indicators increase, including in areas with high population density. The Future of European Cities: In HEATCOST, we explore how the temperature in 36 major European cities will change based on climate models. The results suggest that cities in Southern Europe will be most affected, but depending on the indicators we use, cities in Central, Eastern, and Northern Europe may also experience significant temperature increases. This highlights the importance of detailed climate models to understand extreme climate changes in cities. How Climate Change Affects Health and Agriculture: HEATCOST has examined methods to understand how climate and air pollution affect health and agriculture. We find that while we have good methods to understand the effects on agriculture, more research is needed on health impacts. This is crucial for developing effective strategies to cope with climate change. Air Pollution and Temperature Impact Mortality: We also investigate how air pollution can amplify the relationship between temperature and mortality. A review found that simultaneous exposure to particles (PM10) and ozone (O3) increases the mortality associated with high temperatures. Collaboration and Efforts for the Future: Researchers from HEATCOST also discuss their findings in workshops to collaborate and find solutions. It is essential to increase resources and knowledge to understand the health effects of climate change, especially in poorer countries in the global south. More resources should be allocated to make research findings accessible to decision-makers and policymakers so they can develop better strategies to protect the population.

Preventing poor health has significant direct impacts on human welfare and on the economy of countries, by reducing human suffering and by lowering the strain on the health care services. HEATCOST has improved the capacity and methods to project health impacts of global warming and has contributed research on several aspects related to the health burden of climate change and the links between temperature increases and air pollution. Among the output of the project are projections of health-relevant heat stress indices under alternative climate change scenarios, global impact of climate change on emission of air pollution from wildfires and the associated health burden (including the formulation of the metric fire mortality fraction), assessment of global inequalities in exposure to heat stress and air pollution, and assessment of current knowledge and knowledge needs regarding the joint effects on health of concurring exposure to ambient heat and air pollution. Through the development of methods, metrics, datasets (Climate extreme indices and heat stress indicators), exposure and burden estimates, and projections for the future, HEATCOST has had important academic impacts. E.g. we have drawn the attention of the research community regarding methodological developments for projecting fire emissions due to climate change. The climate extreme indices are widely used by CICERO and others for further analysis, for example within the Research Council of Norway project CATHY (Climate implications of rapid changes in Asian Anthropogenic Aerosol emissions and EU Horizon2020 project CRiceS (Climate Relevant interactions and feedbacks: the key role of sea ice and Snow in the polar and global climate system). Moreover, HEATCOST has contributed to raising attention in the research community about the interactive effects of heat stress and air pollution. HEATCOST results also have potential for important societal impacts. We have received particular attention for the work on wildfires, e.g. from representatives from the European Commission DGs. HEATCOST results are included in Policy Briefs published by the ENBEL project (EU H2020 CSA) and have thus been distributed widely to policy makers and other stakeholders.

HEATCOST is a Belmont Forum project coordinated by CICERO. Partners are Rhodium Group (USA), FMI (Finland), Peking Univ. (China), Red Cross Red Crescent Climate Centre, WHO/WMO Climate&Health Office HEATCOST quantifies global current and future changes in cardiopulmonary (CPD) mortality and morbidity due to extreme heat and air pollution (including from wildfires) under selected climate scenarios, while assessing a diverse set of adaptation mechanisms and strategies, and estimates the associated costs. Extreme heat increases mortality rates and can exacerbate a range of diseases. In particular, heat increases mortality and morbidity for cardiovascular and respiratory diseases (CVD and RD), which together constitute cardiopulmonary diseases (CPD). The risk of wildland fires increases during periods of extreme heat and decreasing precipitation, and can cause intense air pollution. Synergistic effects of extreme heat and air pollution (O3 and PM2.5) on CPD outcomes have been identified. Complex interactions act to exacerbate the effects of extreme events on CPD outcomes. The health risk varies by region, population vulnerability, the built environment and other factors. Populations at highest risk include older adults, children, socially isolated individuals, and individuals with chronic diseases. Health effects due to heat and air pollution is largely preventable to the extent that adaptation measures can be tailored to alleviate vulnerability factors. HEATCOST will review the literature on the E-R relationships between health effects and temperature, including for EU, USA, and China, and establish exposure projections for extreme heat and air pollution based on updated modelling and downscaling efforts. HEATCOST includes a diverse set of adaptation mechanisms, calculates the associated economic and social costs and identifies effective strategies for minimizing adverse impacts. The results will be disseminated to the general public and to decision- and policy-makers.