• Research and White Papers
  • April 2024
  • 9 minutes

Clearing the Air: The conundrum of climate change and the impacts on health

  • Dr. Georgiana Willwerth-Pascutiu
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In Brief

For life and health insurers, identifying approaches to better quantify and predict the impacts of climate change is both critical and challenging. 69ɫƬ's Georgiana Willwerth-Pascutiu outlines some of the many factors to consider and explores steps insurers might take to help make more informed decisions.

These alarming facts have climate scientists asking: Was this a particularly bad year that can be attributed to climate variability as part of a long-term linear rise in global temperatures, or has climate change accelerated and entered a dangerous new phase? 

Fueling the debate is an inability to answer this question with a high degree of certainty, which should only hasten efforts to do so. For the insurance industry, which exists to protect people against uncertainty, identifying approaches to better quantify and predict the impacts of climate change is essential.  

For life and health insurers in particular, this means taking the next step and determining the health implications of rising global temperatures – alongside the related environmental threats of air pollution and ecosystem degradation. For example, what were the direct and indirect, acute and chronic effects on human health from 2023’s Canadian wildfires? Did climate change play a role in the wildfires’ intensity, and if so, can that be quantified?  

Answering these questions requires collecting and analyzing available data, acknowledging the limitations of that data, and applying novel approaches such as attribution science to derive meaningful conclusions. The time to act is now. A holistic approach that treats all environmental threats as a single planetary health emergency will strengthen insurers’ understanding of climate change’s multiple impacts on population health and enable the industry to play its part in addressing the climate crisis.


Every year for the past decade, the World Economic Forum’s annual Global Risks Report has cited environmental degradation as one of the five most damaging global risks. In addition, the 2023 Global Risks Perceptions Survey (GRPS) lists climate- and nature-related risks, such as natural disasters and extreme weather events, biodiversity loss, and ecosystem collapse, among the top 10 risks by severity expected to manifest in the next decade.2

The earth’s changing climate trends have also become more broadly acknowledged as both an environmental crisis and a cause of many public health challenges.

The term “environmental health,” coined decades ago, refers to a branch of public health that assesses the environment’s impacts on human health and wellbeing. A growing body of evidence highlights the increasingly negative effects of climate hazards on population health. 

While climate variability and extreme weather events have been documented for centuries, global temperatures are increasing at a rate not seen in the past 10,000 years, and climate change is changing the location, intensity, and frequency of extreme weather events.3 The task of understanding the resulting impacts on human health can be overwhelming. 

Attribution science, a growing area of climate study that deals in probabilities, observability, and validity, may help quantify the impacts of climate change. Scientists in this new field are analyzing observational data from extreme weather events, such as hurricanes, heat waves, or floods, and developing models to determine the extent to which these events may be caused — or influenced — by climate change. 

The process begins with a clear understanding of available data on natural disasters’ specific impacts on mortality and morbidity. Following a record-breaking 2023 Canadian wildfire season, wildfires offer a timely weather event to use as an example. 

climate with smoggy skyline
Learn more about climate change’s impact on the world and on insurance: "Prioritizing Life and Health in a Changing Climate through Innovative Insurance 69ɫƬ."

Extreme weather event case study: wildfires 

Although fires can play a role in the natural cycle of certain ecosystems, mounting evidence suggests that rising atmospheric temperatures, changing precipitation patterns, and dryer climates are increasing the incidence and severity of wildfires. 

The 2022 Lancet Countdown reported human exposure to days of very high or extremely high fire danger increased in 61% of the world’s countries from 2001-04 to 2018-21.4 In addition, the 2023 Intergovernmental Panel on Climate Change (IPCC) report stated that future wildfires are likely to intensify as temperatures rise.5 

Wildfire-attributable health consequences are related both to exposure to fire and to its smoke, which can travel thousands of miles and affect the health of millions of people. 

Canada’s record-breaking 2023 wildfire season clearly illustrated these hazards. By June 6, so much smoke from the fires had drifted south that New York City’s Air Quality Index (AQI) reached 480, the worst air pollution of any major city that day. Around the same time, midwestern U.S. cities such as St. Louis experienced hazy skies and unhealthy AQIs in the 200s. Even across oceans, Europe and northwestern Asia’s air quality was affected. 

Wildfire smoke is a complex mix of particulate matter and gaseous pollutants. PM2.5 particles, the most concerning, are a group 1 carcinogen according to the International Agency for Research and Cancer. These tiny particles penetrate deep into the lungs, and from there enter the circulatory system and eventually reach every major organ in the body. 

The PM2.5 in wildfire smoke is the most toxic type: its PM2.5/carbon monoxide ratio is far higher than that of smoke generated by urban pollutants; its particle sizes are smaller; and exposure to these particles in wildfire smoke is often accompanied by co-exposure to high temperatures and other harmful factors. Wildfire smoke components also react with nitrous oxide, a byproduct of combustion engine activity, which contributes to rising ozone levels in urban areas and can pose a significant risk to respiratory health.6 Health Canada estimates that between 2013 and 2018, as many as 240 premature deaths per year were attributable to short-term exposure to PM2.5 in wildfire smoke, and up to 2,500 were attributable to long-term exposure.7

In addition, a global time series study in 749 locations found that annually, during the study period (2000 to 2016), 0.62% of all-cause deaths, 0.55% of cardiovascular deaths, and 0.64% of respiratory deaths were attributable to the acute impacts of wildfire-related PM2·5 exposure. The study also stated that the pooled relative risks of mortality associated with each 10 μg/m3 increase in the three-day moving average (lag 0 to 2 days) of wildfire-related PM2·5 exposure were 1.019 for all-cause mortality, 1.017 for cardiovascular mortality, and 1.019 for respiratory mortality. 8

Furthermore, the study noted that PM2.5 levels due to wildfires are expected to continue to increase: By 2100, within the contiguous U.S. alone, concentrations will rise by between 55% to 190%, accounting for more than 50% of all ambient PM2.5. 
To better quantify wildfires’ range of health implications, insurers would benefit from access to a research focus beyond acute effects of exposure – one encompassing the chronic and longitudinal health outcomes of populations exposed to wildfire outcomes. 

Modeling wildfire-related mortality

Climate change risk analysis requires understanding the estimated wildfire PM2.5-related premature mortality excess burden in extreme climate scenarios. 

The four Representative Concentration Pathway (RCP) scenarios – RCP 2.6, RCP 4.5, RCP 6, and RPC 8.5 – indicate possible future greenhouse gas concentrations in the atmosphere and their potential impacts on future global temperatures. RCP 8.5, the most severe scenario, represents steadily rising emissions, resulting in a median increase in the global temperature by the end of the century of 4.4 degrees Centigrade. 

According to 2021 research from the U.S. Environmental Protection Agency, in the western U.S. alone, PM2.5 exposure changes combined with population projections may result in a wildfire PM2.5-related premature mortality excess burden in the year 2090’s RCP 8.5 scenario that is roughly 3.5 times larger than in the baseline period.9 

Climate change, air pollution, and mortality 

Climate change and air pollution are, in many ways, two sides of the same coin, as both are driven mainly by the burning of fossil fuels.

Multiple studies cite air pollution as the world’s fifth leading mortality risk factor.10 However, it is important to recognize that premature mortality related to air pollution depends on the joint effects of climate and anthropogenic emissions, population size, age structure, and healthcare resources. 

In the U.K., for example, outdoor air pollution has been shown to cause roughly 1 in every 10 cases of lung cancer. The U.K. Health Alliance on Climate Change reported in 2023 that the country ranked #101 of 131 countries in terms of poor air quality, and London, the capital, had an average PM2.5 concentration of 9.6 μg/m³ (most cities are below 10 μg/m³).11 In the U.S., meanwhile, air quality varies from region to region, but according to the Centers for Disease Control and Prevention, as many as 20% of cases of lung cancer occur among people who have never smoked – a percentage that is increasing. 

Contrasting these already significant health risks in developed countries such as the U.K. and U.S. with air pollution’s impacts on health in a developing country such as India is revealing. India ranks #8 of the 10 most polluted countries in the world according to the World Air Quality Index Report 2023 and has average PM2.5 levels of ~ 53.3 μg/m³. A recent study by thoracic specialists at the Medanta Cancer Treatment Center in New Delhi found that the profile of patients diagnosed with lung cancer changed significantly from 2012 to 2022. According to the study, 50% of lung cancer patients in North India are now non-smokers, more than 21% are under age 50, and lung cancer’s prevalence among women is increasing. In the words of Dr. Arvind Kumar, founder and managing trustee of the Lung Care Foundation, “There are no non-smokers in polluted countries.”12

Scientists and medical professionals stress the need to fight air pollution, the cause of about seven million premature deaths a year. Climate experts, however, have warned that implementing technologies to reduce air pollution can accelerate global warming short term. For example, China's decade-long war on air pollution has cut sulfur dioxide emissions by nearly 90%, but because atmospheric SO2 no longer diffuses the sun’s radiation, average temperatures in the country have risen by 0.7 degrees Celsius since 2014. Nevertheless, these short-term temperature increases should not dissuade efforts to combat air pollution.

It may not be readily apparent to insurers that a specific claim may be tied to one or more environmental hazards, as death certificates generally list only one leading cause of death and do not leave space for additional information on contributing factors such as air pollution. Nevertheless, environmental perils are clearly emerging as leading morbidity and mortality drivers worldwide, and climate change could further affect these trends. 

Climate change impacts the fundamentals of human existence: water, air, food and shelter. Find out more about the effects of suboptimal temperatures on mortality and estimate impacts under various climate pathways.

Extreme weather event intensification: hurricanes 

Are extreme weather events becoming more common and more destructive? An analysis of hurricanes may provide valuable insights. 

For the past two decades, hurricanes have been growing in frequency, intensity, and impact. One of the strongest in recorded history was Hurricane Otis, which made landfall in late October 2023 near Acapulco, a major tourist destination on Mexico’s Pacific coast. In less than 24 hours, Otis intensified with unprecedented rapidity, growing from a tropical storm to a Category 5 hurricane. It claimed more than 40 lives and caused property damage that current estimates say could climb as high as $15 billion ($6.5 billion for the insurance industry).13 

Climate scientists see rapid hurricane intensification as a consequence of climate change. One factor has been global ocean water temperatures, which have been rising due to the absorption of heat generated by increased atmospheric CO2 levels. CO2 concentrations are now 50% higher than in the preindustrial era, which has increased ocean water temperatures and consequently provided more energy for storms to form and intensify. 

Until recently, hurricane damage could be mitigated to a certain extent as hurricanes intensified gradually, allowing for timely advance planning, public advisory issuance, and resource allocation. Climate change is now making it harder to predict hurricane behavior, and therefore more difficult to implement advanced mitigation plans. 

Extreme weather events: direct and indirect mortality 

The frequency, intensity, and duration of many extreme weather events, not just hurricanes, have been increasing worldwide. According to the World Meteorological Association, the number of reported climate- and weather-related disasters increased fivefold from 1970 to 2019.14

Floods are the most common extreme weather event, making up 43% of natural disasters worldwide, and are projected to increase in severity, duration, and frequency, posing additional adverse impacts on environments, economies, and human health.15

The 2023 Lancet Countdown highlighted that due to well-implemented adaptive measures, the lethality of floods and storms declined in countries with high and very high Human Development Index (HDI) numbers and remained statistically unchanged in other areas. 

Determining mortality due to floods requires a surveillance approach that searches death records for specific mention of links to a flood event. While this approach can capture flood-related deaths due to causes such as drowning, electrocution, and hypothermia, a substantial number of other flood-related deaths can be overlooked, as they are due to secondary causes such as contaminated food and water, disrupted access to medical care, and mental health disorders.

A 2023 study based on data from 35 countries16 demonstrated that mortality risks among populations exposed to floods increase during the first 25 days after the flood and then return to baseline values at around 60 days. The association of floods with higher risk of all-cause, cardiovascular, and respiratory mortality was stronger in older individuals and those in lower socioeconomic groups, varying by local climate type.

Disruptions to healthcare access and delivery due to floods and other extreme weather events are a significant risk factor and especially concerning for patients with cancer, as delays in cancer diagnosis and treatment initiation can worsen cancer prognosis.

Consider this: A 2016 study found that in Ghana, for every day a power outage lasted longer than two hours, total hospital mortality increased by an estimated 43%.17

There is also a strong link between natural disasters and increased mental health disorders. Survivors experience PTSD, depression, anxiety, and increased stress due to limited resources (water, food, finances), which can lead to increased interpersonal violence and crime. 

A more holistic approach to assessing direct and indirect mortality and morbidity associated with natural disasters is clearly needed. 


The solution: expanding knowledge 

Attribution science and climate trends

With the intensity and frequency of extreme weather events increasing, the discipline of attribution science, which focuses on understanding the role of climate change in weather events, is attracting attention.18

The World Weather Attribution initiative is a collaboration of scientists around the world analyzing extreme weather events to ascertain how much climate change may have contributed to their development. These scientists also study historical climate data to compare the likelihood or severity of a natural disaster occurring today to what might have happened in a world without global warming, including impacts on human health.

Heat-associated morbidity and mortality, for example, vary according to population (urbanization, age, presence of comorbidities, lifestyle), society, and factors relating to the extent of human physiological adaptation. Scientifically sound and methodologically improved climate indicators, together with detection and attribution studies, may be able to provide more accurate attribution of factors affecting climate change, project future risks, and offer new perspectives on the complex relationship between health and climate change.

Consider this: Recent analysis shows that in 2020, more than 60% of days with health-threatening high temperatures were more than twice as likely to occur due to human-driven climate change. The 2023 Lancet Countdown19 reported that heat-related deaths of people older than age 65 rose 85% compared to 1990-2000, substantially more than the 38% increase expected had temperatures not changed.

This growing field will help scientists determine and quantify climate change’s influence on extreme weather events and will enable life insurers to better understand climate change impacts on morbidity and mortality trends. 

Understanding research limitations

Understanding the limitations of existing research is vital for making accurate assessments of climate change risks. Morbidity impacts of extreme heat events offer a good example of how current data often does not tell the complete story.  

During the past 20 years, extreme heat events have been on the rise, and the number of days of heatwave exposure affecting vulnerable populations has increased substantially. From 2013 to 2022, on average, there were 108% more days of heatwave per year than in 1986-2005 (Lancet 2021 and 2022), and heat-related deaths have risen accordingly.20

Morbidity consequences appear less significant. However, studies based on morbidity data might have underestimated true heat effects if patients had difficulty accessing healthcare services during extreme temperatures, which would explain the observed higher overall effect on mortality than on morbidity. 

Also, new heat-linked health conditions such as Mesoamerican endemic nephropathy (MeN) are emerging. MeN, a chronic kidney disease (CKD) of unknown origin, began to be seen about a decade ago and is now linked to exposure to extreme heat. MeN has pockets of high prevalence among young male agricultural workers in southwest Mexico and Central America. Possible causes include exposure to high temperatures, dehydration, and/or high levels of pollutants. A similar disease pattern is being observed in North America, the Middle East, Africa, and India. If the length, frequency, and intensity of heatwaves increase, it could ultimately trigger epidemics of CKD in regions where people are exposed to extreme heat.

Adopting a long-term approach

Most scientific literature on climate change and health focuses on acute or short-term effects, but conducting more comprehensive and long-term analyses could help overcome current research limitations.

Future generations are likely to experience more frequent climate extremes. Children less than one year of age are particularly vulnerable to extreme heat and are now exposed to twice as many heatwave days as they were from 1986 to 2005.15

Life course epidemiology (LCE), an approach defined as “the study of long-term effects on later health or disease risk of physical or social exposures during gestation, childhood, adolescence, young adulthood, and later adult life,” focuses on the relationship between early psychosocial, behavioral, and environmental exposures and later-life health impacts.21 An LCE-based approach to climate and health research could contribute to a greater understanding of the latent and cumulative effects of early-life exposures over a lifespan. 


The environmental crisis the earth faces stems from three interlinked causes: climate change, air pollution, and biodiversity loss. While this paper focuses mainly on climate change, all three challenges need to be addressed together as one global health emergency to ensure humans can continue to inhabit a livable planet. The accelerating decline in biodiversity driven by human-generated activities such as deforestation and industrial agriculture, for example, is having far-reaching impacts on health, from increased transmission of zoonotic diseases (Zika, Ebola, Lyme disease) to limiting the natural world’s ability to absorb greenhouse gas emissions.  

Expanding public health assessments to incorporate environmental exposures and other climate-related factors could generate new insights into disease prevention and improve health outcomes. More reliable and robust indicators, which can more effectively track spatiotemporal changes in weather and climate and integrate demographic data, will enhance estimates of health-related outcomes in exposed population groups.

The future impacts of climate hazards on human health will largely depend on governmental actions. These could include enhancing infrastructure to address accelerated climate hazards, implementing adaptation strategies such as mandating additional resources for healthcare and building societal resilience.

Insured lives are generally less exposed to and affected by climate perils, have better access to healthcare services, and are therefore more likely to experience more favorable incidence and mortality trends. That said, as noted in the Geneva Association’s recent climate report: “Although life and health insurers have not been significantly impacted by climate change to date, that will not remain the case as climate events become more frequent and severe.” Insured lives are clearly not immune to the risks of climate change, and if the industry is to grow and fulfill its charge to bring financial protection to more people, insurers need to design innovative solutions that prioritize inclusion.

The insurance industry now has an opportunity to play a leadership role in combating the climate crisis by promoting awareness, providing education, and inspiring, motivating, and incentivizing populations to modify behaviors in ways that will benefit their own health and the planet’s health. 

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Meet the Authors & Experts

Georgiana Pascutiu
Dr. Georgiana Willwerth-Pascutiu
Vice President and Medical Director, Global Medical


1. Climate change indicators reached record levels in 2023: WMO 
4. The 2022 report of the Lancet Countdown on health and climate change: health at the mercy of fossil fuels - The Lancet
8. Mortality risk attributable to wildfire-related PM2·5 pollution: a global time series study in 749 locations - The Lancet Planetary Health
16. Mortality risks associated with floods in 761 communities worldwide: time series study | The BMJ
20. A life course epidemiology approach to climate extremes and human health - The Lancet Planetary Health