Climate change is already reshaping health risks, report warns
Table of Contents
CLIMATE change is increasingly shaping how people experience health, from rising heat stress to the spread of infectious disease and the growing strain placed on health systems.
Rather than remaining a distant environmental concern, its effects are now visible in daily life, influencing how bodies cope with heat, how illnesses circulate and how communities recover from disruption.
The 2025 Lancet Countdown Report on Health and Climate Change draws these connections together, using global and regional data to trace how environmental change is translating into health outcomes.
When heat becomes health risk
The report showed health impacts are no longer theoretical. Rising temperatures are extending the number of days considered dangerous to human health, increasing the likelihood of heat exhaustion, dehydration and cardiovascular stress.
In tropical countries, where heat is already part of the climate baseline, the added intensity and duration of extreme heat further reduce the body’s ability to recover, particularly among older adults, infants and those with existing health conditions.
Selangor environment and public health exco Jamaliah Jamaluddin said the findings reflect conditions Malaysians are already living through.
“The Lancet Countdown 2025 report reveals that the health impacts of climate change are worsening and delay in action is costing lives and livelihoods around the world.
These are not distant projections, they are real, measurable harms that are happening now,” she said.
Extreme heat is identified as one of the most immediate and widespread health threats. Globally, heat-related deaths now number in the hundreds of thousands each year, with most heatwave days directly linked to human-driven climate change.
Beyond mortality, prolonged exposure to high temperatures affects sleep quality, limits safe outdoor activity and increases hospital admissions for heat-related illness.
Everyday actions such as exercising outdoors or working in open environments increasingly carry health risks rather than benefits, particularly when heat exposure becomes sustained rather than episodic.
Disease patterns are shifting
Climate change is also altering how infectious diseases spread. Warmer temperatures and shifting rainfall patterns are expanding the habitats of disease-carrying mosquitoes, increasing dengue transmission risk across much of Southeast Asia, including Malaysia.
These environmental shifts affect when outbreaks occur, how long transmission seasons last and how widely diseases spread, placing sustained pressure on health services rather than short-term surges.
Lancet Countdown lead collaborator Dr Meisam Tabatabaei said Malaysian data showed exposure to heat has risen sharply among vulnerable groups.
“In 2024, people older than 65 years and infants younger than one year experienced over 300% and close to 400% more days of heatwaves per person respectively compared with the baseline 1986–2005,” he said.
Prolonged heat exposure, he said, affects everyday activities, turning routine outdoor exercise and work into potential health hazards, particularly for those without access to cooling or flexible schedules.
Indirect impacts on public health
From a public health perspective, climate impacts are often felt indirectly, said Health Ministry disease control deputy director Dr Thahirahtul Asma Zakaria. Environmental disruption in one sector frequently translates into health outcomes elsewhere, creating layered and cumulative effects.
“We at the Health Ministry are the end receiver of all the impacts of climate change. If climate change affects agriculture it will cause food insecurity and malnutrition. If it affects forests and biodiversity it will change disease vectors. All of this leads to direct impacts on human health,” she said.
Floods, heatwaves and vector-borne diseases such as dengue remain recurring pressures, she said, while mental health impacts linked to evacuation, displacement and disaster recovery are becoming more visible.
Stress, anxiety and trauma often persist long after physical damage is addressed, adding to the health burden carried by affected communities.
“Mental health is one of the emerging issues related to climate change, especially during and after disasters,” she added.
Health at the centre of climate change
Romanello said the findings underline how closely climate and health are now intertwined, with delays in action translating directly into harm.
“The Lancet Countdown shows that climate change is already undermining the foundations of health through heat exposure, extreme weather and the spread of infectious diseases, and the longer action is delayed the greater the risk to people’s health and survival,” she said.
Taken together, the report places health at the centre of the climate discussion. Heat exposure, infectious disease and mental well-being are no longer secondary effects but part of how climate change is already being lived and managed, with health outcomes offering a clear measure of resilience in a warming region.
