Climate Change

The Impact of Climate Change on Health

Mass restrictions on movement, commerce and industrial activity—intended to slow the coronavirus pandemic—have slashed air pollution levels around the world.1 But once the pandemic has passed and economic activity has resumed, we’ll be back where we were, facing an impending climate crisis that could exacerbate health challenges around the world.  

These challenges can range from deaths caused directly by floods or heat waves, to higher rates of skin cancer as the ozone layer thins or of insect-borne disease, to harder-to-measure consequences such as mental health disorders linked to forced migration.
“A child born today will experience a world that is more than four degrees warmer than the preindustrial average,” the medical journal Lancet said in its 2019 Countdown on Health and Climate Change, “with climate change impacting human health from infancy and adolescence to adulthood and old age.”          

It’s not easy to measure the effects on mortality, given the difficulty of teasing out climate change factors on health from other issues that also have a bearing such as urbanization. Nonetheless, the World Health Organization (WHO) estimated in 2018 that from 2030 to 2050, an additional 250,000 people will die as a result of climate change that is being accelerated due to human activities, predominantly the burning of fossil fuels.3 

That figure includes 38,000 elderly people suffering from heat exposure, 48,000 from diarrhea, 60,000 from malaria, and 95,000 from childhood malnutrition. The WHO estimates that the health effects of climate change will impose costs of US$2billion to US$4billion a year in that period. Experts say such collaboration is needed to help us understand the broader effects of climate on health, and perhaps develop strategies to combat them.      

“I was most struck by the breadth of effects,” said Luc Kuykens, Senior Vice President, Sanofi Global Health Programs. “As an infectious-diseases guy, I always thought that climate change had an effect on vectors—think of malaria, dengue, Lyme disease—but when you look at the totality, there are so many other effects on human health.”

With a background in fieldwork in infectious diseases in Africa, Haiti and elsewhere, and in vaccines at Sanofi Pasteur, Kuykens has had a first-hand view of illnesses that are most affected by climate change. Among those that fall under Sanofi health initiatives are malaria, dengue, tuberculosis, asthma and mental health.

The burden falls disproportionately on those least equipped to handle it, he explained, “with poorly equipped healthcare systems suffering immediately from the effects of climate change on health.” 

Isabelle Villadary, Head of Malaria and Tuberculosis Programs, Global Health at Sanofi, breaks down the health impacts into five main categories:

  • respiratory allergies and asthma
  • mosquito- and tick-borne diseases, including malaria, dengue, West Nile virus and Encephalitis
  • diseases related to water quality, such as cholera, diarrheal disease and cryptosporidiosis
  • forced migration due to climate change, which can favor epidemics of tuberculosis and diseases spread by poor hygiene and population density
  • mental health impacts from weather events, such as those documented among low-income populations following Hurricane Katrina in 2005 in the New Orleans area4

Villadary said climate change data and prediction models provide essential guidance in combating malaria, which is transmitted by the infected female Anopheles mosquito. For example, she said, they could help health decision makers in sub-Saharan countries predict the rainy season to put in place a malaria program.       
To make the case for a link, and then to guide future action, the epidemiology of a disease needs to be studied over many years, Kuykens said, then overlaid with, for example, data about change in air quality.  

“It’s a mixture of retrospective epidemiological studies, and then linking them to mathematical modeling into the future,” he said.

Putting it all together will require researchers to collaborate across disciplines, Villadary and Kuykens said. Those include meteorology, climatology and mathematics, and medical research into injuries and fatalities, mental health, respiratory disease and infectious disease—to name a few.

“Looking at the impact of climate change on human health, in its totality across all disciplines and areas is starting to develop,” Kuykens said, “but it’s certainly still nascent.”     



  1. European Space Agency, “Coronavirus lockdown leading to drop in air pollution across Europe,” March 27, 2020. Available at: Accessed March 2020.
  2. The Lancet, “2019 Countdown on health and climate change,” November 16, 2019. Available at: Accessed March 2020.
  3. World Health Organization, Fact Sheet on Climate Change and Health, February 2018. Available at: Accessed March 2020.
  4. Rhodes, J., Chan, C., Paxson, C., Rouse, C. E., Waters, M., & Fussell, E. (2010). The impact of Hurricane Katrina on the mental and physical health of low-income parents in New Orleans. American Journal of Orthopsychiatry, 80(2), 237–247.

This website uses cookies to track its audience and improve its content. By continuing to browse this website, you agree to the use of such cookies.

Click here for more information on cookies