Humankind has never been better at fighting diseases. Researchers are coming up with new vaccines and treatments at an astounding speed.
But climate change is making public health gains a lot harder to achieve and undoing some of the world’s hard-earned progress.
Consider the mosquito, which kills more humans than any other creature.
Until very recently, fatalities from malaria, which is spread by mosquitoes, were on the decline. The widespread use of insecticides and bed nets had brought the number of deaths from malaria down to fewer than 600,000 in 2021, according to the World Health Organization, from roughly 900,000 in 2000.
But climate change has expanded the warm areas where the most dangerous species of mosquitoes, those that carry deadly diseases, can breed. As a result of those factors, and also because of the rapid evolution of mosquitoes, malaria deaths are once again on the rise, as my colleague Stephanie Nolen, The Times’s global health reporter, writes in an astounding new series about the insects and all the ways we have to fight them.
And, it’s not just malaria. Increasing temperatures have also been a gift to Aedes aegypti, the mosquitoes that transmit dengue, Zika virus and chikungunya. Dengue infections have happened in places that had never seen the virus, like France, and have grown worse in countries that have long battled the disease, like Peru and Bangladesh.
The broader public health effects of climate change go beyond infectious diseases.
Heat waves have pushed temperatures beyond what workers in Qatar can survive, wildfires have made the air hazardous in parts of Canada and the United States, and floods have contaminated drinking water sources in Malawi.
A recent study found that more than two billion people have been exposed to at least a day of fire-related air pollution each year between 2010 and 2019, undoing some of the gains against respiratory diseases. In the United States, researchers concluded that the smoke from wildfires has undone almost a quarter of the progress from the Clean Air Act of 1970.
Floods around the world also created an “unprecedented” number of deadly cholera outbreaks, according to the World Health Organization.
Pakistan, for example, had few cholera cases before the floods that submerged a third of the country last year. A few months after the floods, the W.H.O. reported 987 confirmed cases of cholera, and there could be a lot more: Not even 2 percent of 1.4 million cases of watery diarrhea were tested for the disease.
With all that in mind, global health experts are warning that climate change is now the biggest single threat to public health.
“Obviously, there’s economic hardship, as well, that will be introduced by climate change,” Neil Buddy Shah, who heads the Clinton Health Access Initiative, told me. “But everything from air pollution to extreme weather events to chronic weather changes will result in harm to human health.”
New challenges emerge
A warming world is also creating new diseases and ways for people to get sick. Heat waves are making heatstroke deaths increasingly common, for example. The summer heat killed at least 61,000 people in Europe last year.
But people are not affected equally by these changes. Communities that are displaced by extreme weather events are some of the most vulnerable to the health effects of global warming. Stephanie told me she had been shocked to learn that 8 percent of malaria cases were among refugees, who suffer from the lack of proper housing, sanitation and safe water sources.
“Paradoxically, with cholera, even more than too much water, it’s not enough water that creates a problem,” Stephanie told me.
When there are droughts or people are displaced by disasters, they crowd near smaller water sources. This both makes it likelier for that body of water to get contaminated and for it to then spread a disease to a larger number of people.
Scientists also say environmental destruction very likely helped spread some diseases to humans, including Covid and Ebola. Deforestation, for example, draws people closer to animals that can transmit diseases, according to Larry Brilliant, the American epidemiologist who helped eradicate smallpox.
“The way we live, the way in which we have dealt with the forests, the desire for meat, increased transportation, all of which are antecedents to climate change, are also antecedents to pandemics, because today animals and humans live in each other’s territory like never before,” Brilliant said. “Human beings are meeting viruses at the urban-wildlife interface.”
Ways to adapt
Global health experts say they are heartened that climate change is garnering more public attention, but are worried that related health challenges are receiving less attention.
“There’s a real risk that we declare victory prematurely on these global health wins and funding moves away from it,” Buddy Shah said. Only 0.5 percent of climate funding goes to health projects, according to the W.H.O.
For the first time this year, the annual global climate summit known as COP will have a Health Day for countries to focus on adaptation strategies.
“There’s been 28 COPs, and this is the first time that there’s a Health Day,” Buddy Shah said. “That’s telling people how absent health has been in the climate agenda.”
— Additional reporting by David Gelles.
‘Wind is free fuel’
The wind is a natural propellant that oceangoing vessels have depended on for centuries. And as the shipping industry tries to move away from fossil fuels, sails are making a comeback — from giant kites to sky-high composite-glass structures.
“We want to decarbonize. Why not use what’s available?” said Jan Dieleman, president of Cargill Ocean Transportation, which charters about 700 ships. “Wind is free fuel.”
The worldwide shipping industry is responsible for about 3 percent of the greenhouse gases that are dangerously heating the planet. That translates into about one billion metric tons of carbon dioxide and other gases annually, a figure that is rising as global trade increases.
Some 11 billion tons of cargo are shipped by sea each year, accounting for as much as 90 percent of the world’s traded goods. Nearly all of it is enabled by burning heavy fuel oil.
The Swedish company Wallenius Marine is developing wind-powered ships with the aim of lowering vessels’ carbon emissions by as much as 90 percent. The company has sponsored Abba Voyage, a virtual concert performance featuring the Swedish pop band that has been running in London since last year.
Wallenius has also secured the rights to name its wind-powered vessels after Abba songs, though it has not yet chosen a song for its ships.
“Some are better than others,” Jeppsson said. “Maybe not S.O.S.”
— Cara Buckley
Other climate news
Wirecutter, the Times’s product review website, is launching Emergency Kit, a pop-up newsletter that teaches you how to prepare for natural disasters and other emergencies. Every Thursday for the next three weeks, you’ll receive practical advice and rigorously tested recommendations for essential gear.