From heart attacks and heat exhaustion to mental health problems and spreading tropical diseases, the climate crisis is threatening more and more people worldwide, according to a report published today.
The 128 leading scientists behind the Lancet Countdown Report warn the consequences of rising global temperatures have never been more threatening to human health.
“This year’s health stocktake paints a bleak and undeniable picture of the devastating health harms reaching all corners of the world,” said Marina Romanello, executive director of the Lancet Countdown, an independent international research collaboration, at University College London.
Heat-related deaths have surged 23% since the 1990s, according to the analysis, with rising temperatures claiming over half a million lives every year. Wildfire smoke was linked to a record 154,000 deaths in 2024, while air pollution from the burning of fossil fuels kills 2.5 million every year.
Smoke from wildfires harms the lungs, heart and even babies in the wombImage: Cesar Manso/AFP/Getty Images
Health risks increased in last year
“We’re seeing millions of deaths that are occurring needlessly every year because of our persistent fossil fuel dependence, because of our delay in mitigating climate change and our delays in adaptation to the climate change that cannot be avoided,” said Romanello.
The Lancet Countdown report is considered to be a renowned indicator of the scientific links between health and global warming. These are becoming more pronounced as climate change, driven by the burning of coal, oil and gas, continues to wreak havoc across the planet.
Last year was the warmest on record and saw CO2 levels in the atmosphere jump to new highs. This resulted in the average person experiencing a record extra 16 health-threatening hot days due to climate change. This increased to 20 additional heat wave days on average for the most vulnerable groups in society, such as babies and those over 65.
According to the report, 13 out of 20 indicators that represent human health risks have increased significantly in the past year.
The most worrying aspect is that almost all indicators are going in the wrong direction, explained Romanello.
While renewables are booming authors say the world is still too reliant on fossil fuelsImage: Ng Han Guan/AP Photo/picture alliance
Health and economic costs
Climate change is supercharging extreme weather events that are becoming more frequent and intense around the world.
Heat waves — the most deadly form of extreme weather — can overheat the body, straining vital organs and making it difficult to sleep. Heavy flooding, such as that witnessed in Pakistan this year, can lead to contaminated drinking water and the spread of infections, while droughts are exacerbating malnutrition and hunger as crops fail. Smoke from wildfires — which in 2024 burned an area of land larger than India — harms the lungs, heart and even babies in the womb.
Infections can spread in the aftermath of disasters such as extreme floodingImage: SHAHID SAEED MIRZA/AFP/Getty Images
In the aftermath of weather-related disasters, disrupted power and damaged infrastructure can also hinder access to medical care and supplies. According to Romanello, most of the people affected by extreme weather worldwide don’t have health insurance, which leaves them even more vulnerable when it comes to health risks.
These risks are not only costing human lives, they also have an economic impact.
Water or food shortages and catastrophic sanitary conditions following disasters costs hundreds of billions of US dollars annually. Extreme heat alone is estimated to have cost more than one trillion US dollars in 2024 — roughly 1% of global economic output — due to labor losses from illness and absenteeism.
Dengue and tropical diseases are spreading
Mosquitoes, ticks, and sand flies — some of which transmit deadly infectious diseases — are also spreading to more regions as temperatures rise.
Last week, mosquitoes were documented for the first time ever on the northern European island of Iceland, which researchers have linked to climate change. As warmer temperatures open up new habitats for insects, the number of people infected with dengue, malaria, leishmaniasis, and other diseases is increasing worldwide.
Heat waves are the most deadly form of extreme weather Image: Lionel Bonaventure/AFP
In 2024, there was a record number of dengue infections worldwide, with more than 7.6 million cases. “We know that climate change is fueling at least some of that spread,” says Romanello.
Even if not all of these infections are fatal, those who fall ill are often unable to work for weeks, with major economic consequences.
According to the report, the global average transmission potential of dengue has risen 49% since the 1950s.
Mental health also impacted
Climate change is also increasing the risk of mental illness.
When someone experiences an extreme weather event such as a forest fire, hurricane, monsoon, typhoon or extreme flooding, it can lead to post-traumatic stress disorder, said Jenni Miller, executive director from Global Climate and Health Alliance, a US non-governmental organization.
For example, poor harvests due to droughts, water shortages, or a loss of livelihood can cause anxiety and lead directly or indirectly to mental health problems. This is exacerbated by lack of sleep due to excessively hot nights, according to the report.
Authors say health systems need to be better equipped to deal with climate changeImage: Daniel Dal Zennaro/dpaweb/dpa/picture-alliance
Preventing further illness and death
The authors of the report call for three key measures in mitigating the health consequences of the climate crisis.
First, renewable energy must be expanded to curb rising global temperatures. Clean energy, which has boomed in recent years, has helped reduce air pollution and prevent over 160,000 deaths between 2010-2022, according to Romanello.
Measures to adapt to climate change, such as making residential buildings and public infrastructure fit for extreme weather conditions, must now also be accelerated. And lastly, scientists say global healthcare systems urgently need to be adapted and equipped to face the additional challenges climate change presents.
This article was originally written in German.
