From heart attacks and heatstroke to mental health problems and the spread of tropical diseases - the climate crisis is threatening more and more people around the world, a new report warns.
The Lancet Countdown Report is authored by 128 leading scientists. They conclude that the consequences of rising global temperatures have never been more dangerous for human health.
"This year's health assessment paints a bleak and undeniable picture of devastating health damage in all corners of the world," said Marina Romanello, executive director of the independent international research group Lancet Countdown and professor at University College London.
According to the analysis, heatwaves are killing more than half a million people each year, a 23 percent increase in deaths caused by global warming since the 1990s. In 2024, smoke from wildfires killed a record 154,000 people, and air pollution from burning fossil fuels kills 2.5 million people each year, the report said.
Health risks have increased in the past year
"These are millions of unnecessary deaths every year because we continue to rely on fossil fuels, because we delay necessary measures against climate change and because we are unwilling to adapt to inevitable climate change," said Marina Romanello.
The Lancet Countdown report is considered a recognized indicator of the scientific links between health and global warming. They are becoming increasingly 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, with atmospheric CO2 levels reaching new highs. This meant that the average person experienced a record 16 extra days of high temperatures that threaten health – a direct result of climate change. For the most vulnerable groups in society, such as infants and people over 65, this number increased to 20 extra days of heatwaves.
According to the report, 13 of 20 indicators that pose risks to human health increased significantly in the past year. The most worrying aspect is that almost all indicators are moving in the wrong direction, says Romanello.
Climate change is intensifying extreme weather events, which are becoming more frequent and intense around the world.
Heat waves, the deadliest form of extreme weather, can overheat the body, strain vital organs and make it difficult to sleep. Floods can contaminate drinking water and spread infections, while droughts destroy crops and exacerbate malnutrition and hunger. Smoke from forest fires, which burned an area larger than India in 2024, damages the lungs, the heart, and even babies in the womb.
Climate-related disasters can also lead to disruptions in access to medical care and supplies, power outages, and damaged infrastructure. According to Romanello, most people affected by extreme weather events around the world lack health insurance, making them even more vulnerable to health risks.
Hundreds of billions of dollars in damage
These risks not only cost lives, but also have economic dimensions, as water or food shortages and catastrophic sanitation after disasters cost hundreds of billions of dollars annually. Extreme heat alone will cost more than $1 trillion in 2024 (approximately 1% of global economic output) in lost labor through illness and absenteeism.
Mosquitoes, ticks, and sandflies, some of which carry deadly infectious diseases, are also spreading to more regions as temperatures rise. Mosquitoes were recently detected for the first time in Iceland, which researchers attribute to climate change. As warmer temperatures create new habitats for the insects, the number of people infected with dengue, malaria, leishmaniasis, and other diseases is increasing worldwide.
A record number of dengue cases were reported worldwide in 2024 – more than 7.6 million. – – – – – – – – Romanello says. According to the report, the average potential for dengue transmission globally has increased by 49% since the 1950s.
Mental health implications
Climate change also increases the risk of mental illness. When a person experiences an extreme climate event such as a wildfire, hurricane, monsoon, typhoon or extreme flooding, it can lead to post-traumatic stress disorder, says Jenny Miller, executive director of the US-based Global Climate and Health Alliance.
But poor harvests due to drought, water shortages or loss of workers to disease can also cause anxiety and lead directly or indirectly to mental health problems. According to the report, this is exacerbated by sleep deprivation due to excessively hot nights.
Preventing illness and death
The report's authors call for three key measures to mitigate the health impacts of the climate crisis.
First, the use of renewable energy sources must be expanded to limit the rise in global temperatures. Clean energy, which has boomed in recent years, has helped reduce air pollution and prevented more than 160,000 deaths between 2010 and 2022, according to Romanello.
Climate change adaptation measures, such as making housing and public infrastructure more resilient to extreme weather conditions, also need to be accelerated. Finally, scientists say, global health systems urgently need to be adapted and equipped to deal with the additional challenges that climate change poses.
Author: Tim Schauenberg