“January Insights: Unveiling the Health Hazards Linked to Climate Change”

Dann Mitchell, Professor of Climate Science at the University of Bristol, has made this appeal in a perspective op-ed released today in the journal Nature.

Prof Mitchell, who focuses on extreme heat events, insisted that future climate evaluations must incorporate the prolonged effects on humans, cautioning that “the repercussions for our bodies from continuous exposure to heat, drought, and wildfire smoke will accumulate.”

He is spearheading the UK Climate Change Risk Assessment (CCRA4) – Health and Wellbeing report for the government’s Climate Change Committee, an independent review of the associated hazards and possibilities.

Last year was recorded as the warmest year ever, surpassing 1.5 degrees of warming for the first time since preindustrial periods, and 2025 has already experienced some of the most lethal and devastating wildfires in California’s history.

Some of the harmful effects are evident, such as deaths due to heatstroke and heightened hospital admissions of the elderly and infants during heatwaves, which impose greater pressure on weaker, more susceptible bodies.

“However, there exists a cumulative, long-lasting impact, which requires further examination,” said Prof Mitchell, from the University’s Cabot Institute for the Environment and Joint Chair in Climate Hazards for the Met Office Academic Partnership (MOAP).

For example, frequent and persistent exposure to heatwaves and droughts may result in elevated rates of kidney disease due to regular encounters with dehydration and electrolyte imbalances. Struggling to sleep on hot, humid nights is often merely seen as an inconvenience, yet Prof Mitchell noted that poor sleep quality correlates with reduced physical activity, diminished mental well-being, cognitive decline, and a weakened immune system.

Other ramifications may be even more extensive and perilous.

“The development of fetuses is influenced by the conditions their mothers and they themselves are subjected to, which will affect their health in the future,” Prof Mitchell added.

“On a fundamental level, environmental stressors can alter gene expressions. For instance, research indicates that adults who experienced episodes of hot, arid weather while in utero have a heightened likelihood of suffering from high blood pressure as adults, years later.”

Fully and accurately measuring acknowledged public health threats poses difficulties due to incomplete health data and the complexities regarding how individuals experience various stressors.

Prof Mitchell stated: “The burden of mortality and illness is likely far greater than what current models can estimate.”

He urged researchers and public health officials to reflect upon and analyze four critical areas: the varying timelines of how different health problems will emerge in a changing climate; consequences of environmental issues resulting from increased temperatures; socio-economic effects of climate-related calamities; and integrating insights from extensive research on these matters into global climate risk evaluations.

Instances of such lesser-known public health issues include elevated salinity of groundwater due to rising sea levels leading to increased cases of hypertension in coastal populations, and a rise in respiratory ailments stemming from poor air quality following wildfires. Severe weather occurrences, like hurricanes, can result in significant and lasting impacts, such as weakened social networks as individuals relocate and public funding is redirected towards recovery initiatives.

Prof Mitchell concluded: “Even if the outcomes are uncertain, researchers must quantify this health burden…Once we accomplish this, we will realize that the health burden of climate change is considerably more significant than previously understood.”

Integrating findings from various data sources and analytical insights from interdisciplinary specialists will aid in fostering more informed discussions about how to confront this urgent public health challenge. 

The University of Bristol is at the forefront of addressing some of the globe’s most pressing issues; achieving net zero and combating climate change is a primary research focus.

‘The impacts of climate change on human health are escalating,’ a perspective by Dann Mitchell in Nature