The death toll from extreme weather is becoming clearer | Better modeling is starting to reveal the full global health impact of climate change, just as Trump steps up his war on science

> Heat waves, wildfires, floods, tropical storms and hurricanes are all increasing in scale, frequency and intensity, and the World Health Organization forecasts that climate change will cause 250,000 additional deaths each year by the end of this decade from undernutrition, malaria, diarrhea and heat stress alone. Even so, the impact on human health and the body count attributed to extreme weather remain massively underreported — resulting in a damaging feedback loop of policy inaction. Meanwhile, the very people who might fix that problem, at least in the US, are being fired en masse amid the Trump administration’s war on science.

> To understand the death disconnect, consider the wildfires that tore through Los Angeles in January, destroying more than 16,000 buildings and killing 29 people. Within days, research group World Weather Attribution calculated the blazes were made 35% more likely by climate change. By early February, scientists were in the burn zone measuring pollutants that can pass into the lungs, bloodstream and brain when inhaled or ingested. They know the smoke will cause more deaths than the flames did, but it will take years to fully measure those long-term health impacts.

> Those 29 fatalities “are the most obvious casualties of the actual event,” said Jonathan Patz, a University of Wisconsin-Madison professor who researches the health effects of climate change. “But the health impact is far broader in geography and also over time,” he said, highlighting the dangers of wildfire smoke to children’s respiratory health and to pregnant women and their unborn babies.

> That was certainly true in Australia, which endured one of its worst-ever bushfire seasons in 2019-2020, known as the Black Summer. Thirty-three people died from the flames; within months, scientists estimated an additional 429 premature deaths due to smoke that circled the planet and was so thick at times that Sydney and Canberra had the worst air quality in the world. The total death toll after factoring in long-term impacts will likely be much higher.
Separate research from a team at Melbourne’s Monash University — experts at modeling health risks from wildfire smoke — made the cover of the prestigious Nature magazine in 2023. They found that air pollution from increasingly severe and frequent wildfires threatened billions of people, especially in low-income countries.

> A member of that team, Yuming Guo, is now working on a first-of-its-kind study of the net health impact of a large set of environmental factors related to global warming — including heat waves, wildfires, wildfire smoke, floods, tropical cyclones and disease. It will be finished in the next six to 12 months.

> The study will make projections from 2030 to 2100 under scenarios known as shared socioeconomic pathways, which model population, economic growth and greenhouse gas emissions. It will forecast outcomes at varying levels of global warming: temperature increases of 3C, 4C or 5C by the end of the century. Any of those increases would have significant impacts on the planet, but the difference in the number of projected net deaths is what might be described as the world’s body count from climate inaction.

> Guo said he can’t talk about specific figures yet, as the Monash study is unpublished. But he has no doubt that the net number of annual deaths caused by climate change from 2030 will be much higher than the 250,000 forecast by the WHO. The main message from the research, he said, is that “if we make a great effort to mitigate climate change, many deaths will be prevented or avoided.”

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