The climate crisis is a health crisis. Millions of casualties every year

Every fraction of a degree of warming costs lives and livelihoods, said Dr. Jeremy Farrar, deputy director-general of the World Health Organization, summarizing the latest 2025 Lancet Countdown on health and climate change report. Inaction on climate action is exacerbating a health crisis with huge socioeconomic costs. Casualties can be counted in the millions.

Shocking balance of losses

The Lancet report was a collaboration of 128 experts from around the world, and is the most comprehensive summary to date of the health costs of climate change. As in the previous eight editions, 20 indicators describing the health risks and impacts of climate change were put under the microscope – as many as 12 of them have broken infamous records in recent years.

According to the report’s authors, of the 19 heat waves that occurred between 2020 and 2024, 16 were caused by climate change. The most vulnerable groups, infants and seniors, experienced 3-4 times more hot days compared to two decades ago. As a result, mortality from high temperatures has increased by 63 percent since the 1960s, reaching an average of 546,000 per year between 2012 and 2021. The heat waves have taken a toll on the physical and mental health of millions of people, and have further restricted the ability to do outdoor work.

In 2024. 61 percent of the Earth’s land area experienced extreme drought (3 times more than in the 1950s). Combined with high temperatures, it led to reduced crop yields and brought nearly 124 million people to the brink of starvation. The same unfavorable weather has increased the frequency of wildfires, which have contributed to an increase in particulate air pollution – 154,000 people worldwide died from it in 2024 alone.

The global health crisis has been exacerbated by floods and landslides caused by increased rainfall. The heat and humidity also favor the spread of deadly infectious diseases. The report shows that over six decades, the potential for transmission of dengue fever by two species of mosquitoes, Aedes albopictus and Aedes aegypti, has increased by 48.5 percent and 11.6 percent, respectively. The incidence of other mosquito- and tick-borne diseases is also trending upward.

Emissions continue to rise

The effects of climate change include not only deaths, but also reduced workforce productivity, higher levels of absenteeism from work and high health care costs. The report found that heat exposure in 2024 caused a record loss of 639 billion working hours, translating into costs of $1.09 trillion.

Despite these alarming facts, greenhouse gas emissions are steadily rising, and all indications are that global warming could reach 2.7°C by the end of the 21st century. Paradoxically, climate denialism has been gaining momentum in recent years, and more and more governments are losing enthusiasm for taking action to support the climate and protect health. The withdrawal of the United States from the Paris Agreement and the World Health Organization does not bode well for the entire world.

A report by The Lancet underscores that weakening political will has disastrous economic consequences. Fuel giants such as Shell, BP, ExxonMobil and Chevron have begun to back away from or delay their emission commitments. Government spending on net fossil fuel subsidies in 2023 has tripled the amount of declared aid to poorer countries vulnerable to climate change.

Health crisis is due to missed opportunities

The report’s authors emphasize that implementing the goals of the Paris Agreement can support efforts to promote the health well-being of populations. The world is still not taking full advantage of this synergistic effect.

By increasing access to low-cost, renewable energy, we are working to reduce greenhouse gas emissions and reduce health risks from climate change. Green energy can further support economic development and reduce poverty, which is too often a source of disease. Unfortunately, 745 million people worldwide still lack access to electricity, and more than 1 billion are served by health facilities without stable sources of power.

In countries with low Human Development Index (HDI) levels, 88 percent of households use dirty and unsafe fuels. The air pollution they generate was responsible for 2.3 million deaths in 2022. To make matters worse, the war in Ukraine and the ensuing energy crisis have led many countries to support the fossil fuel sector with subsidies – in 15 countries, the sum of such subsidies exceeded the total health care budget.

Another untapped potential driving the health crisis is dietary change. Between 2021 and 2022 alone, mortality from the production and consumption of unhealthy, high-carbon food increased from 148 to 150 people per 100,000 citizens, translating into 11.8 million mostly preventable deaths.

What is changing for good?

Fortunately, not everything in the world is heading in the wrong direction. The report’s authors point out that the share of RES in the total energy mix continues to grow, and in 2022 it reached a record 12.1 percent. According to the think tank Ember, in the first half of 2025 wind and solar farms generated more electricity than coal-fired power plants, which seems to be a turning point in the energy transition.

The positive effects of moving away from fossil fuels are already apparent. In countries with a very high HDI, mortality from PM2.5 air pollution fell by nearly 6 percent between 2010 and 2022, avoiding 160,000 premature deaths per year. The transition also appears to have had a measurable impact on the economy – in 2023, the green energy sector generated 10 percent of global GDP growth and as much as 30 percent of economic growth in the EU. It also provided employment for more than 16 million people worldwide, offering much healthier and more sustainable jobs than the fossil fuel sector.

Noteworthy is the fact that the healthcare sector itself is changing in the right direction – the emissions it generates fell by 12 percent in 2022 compared to the previous year. By March 2025, 116 of the 193 member countries of the World Health Organization (WHO) had prepared National Health Adaptation Plans.

It is necessary to act and inform

The report’s authors call for intensified efforts to reduce climate risks that exceed our adaptive capacity. The progressive energy transition is a driving force that can reduce the global health crisis by spreading access to electricity and reducing air pollution. It is encouraging that local governments, community and private organizations, and even the health sector itself are getting involved in the transition.

Continuing existing efforts is as important as fighting populism, misinformation and climate denialism, and the responsibility for this falls on the shoulders of the scientific community, the media and world leaders. It is crucial that the public understands the relationship between climate change and health and can make the right decisions based on facts.

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In the article, I used:

The 2025 report of the Lancet Countdown on health and climate change,Romanello, Marina et al.The Lancet, October 28, 2025

Global Electricity Mid-Year Insights 2025, Ember, 07 October 2025