The report compared human health consequences under two scenarios: one in which the world meets the commitments laid out in the Paris Agreement and reins in emissions so that increases in global temperatures remain “well below 2 degrees Celsius” by the end of the century, and one in which it does not.
The report, published Wednesday, found that failing to limit emissions would lead to health problems caused by infectious diseases, worsening air pollution, rising temperatures and malnutrition.
“With every degree of warming, a child born today faces a future where their health and well-being will be increasingly impacted by the realities and dangers of a warmer world,” said Dr. Renee N. Salas, a clinical instructor of emergency medicine at Harvard Medical School and lead author of the United States policy brief that accompanied the report.
“Climate change, and the air pollution from fossil fuels that are driving it, threatens the child’s health starting in the mother’s womb and only accumulates from there,” she said.
Children are especially vulnerable partly because of their physiology.
“Their hearts beat faster than adults’ and their breathing rates are higher than adults’,” said Dr. Mona Sarfaty, the director of the program on climate and health at the Center for Climate Change Communication at George Mason University, who was not involved in the report.
As a result, children absorb more air pollution given their body size than an adult would in the same situation.
But unless nations halt emissions, air pollution, which, according to the report, killed seven million people worldwide in 2016 alone, will quite likely increase. The burning of fossil fuels such as coal and gas also releases a type of fine air pollution called PM 2.5 that can damage the heart and lungs when inhaled. Exposure to PM 2.5 air pollution is correlated with health problems such as low birth weight and chronic respiratory diseases like asthma.
Research published in The New England Journal of Medicine after the passage of policies designed to improve air quality “shows that the children who grew up when the air was better quality literally had more functioning lung tissue,” Dr. Sarfaty said.
In addition to the emissions associated with burning fossil fuels, the report said future generations would be exposed to a growing source of fine-particulate pollution: wildfires.
As temperatures rise, wildfires are becoming more frequent in part because hotter temperatures dry out vegetation, making it easier to ignite. The smoke, like the smoke that comes from burning fossil fuels, has negative health effects.
According to the report, since the middle of this decade there has been a 77 percent increase in the number of people exposed to wildfire smoke worldwide. Much of that growth has been in India and China. The 2018 California wildfire season, though, when the Camp Fire became the state’s deadliest and most destructive blaze in terms of acres burned, and this year’s wildfire season make it clear that increasing wildfires are also happening in the United States.
Across the Western United States, the rise of giant wildfires has worsened air pollution enough to erode some of the air-quality gains from the Clean Air Act.
“You have young kids escaping fires that are going to be, in effect, challenged for life,” said Gina McCarthy, a former administrator for the Environmental Protection Agency. “There are mental health issues happening as a result of these climate events and fires and floods that children have never had to face, certainly not to the frequency and intensity that they have to face now.”
The report said that there were many links between climate change and mental health, including the loss of property and the loss of livelihoods but stopped short of quantifying the impact.
Part of the exposure risk that children face is simply that they spend more time outside than adults. Coupled with their differing physiology, it makes them more susceptible to fine particulate pollution. These same factors also mean they are more likely to suffer from the effects of extreme heat associated with climate change; eight of the 10 hottest years on record have happened this decade.
The European heat waves in 2003 lead to the deaths of 70,000 people. “We know that climate change had its fingerprints there and that’s concerning,” said Dr. Nick Watts, the report’s executive editor, adding that subsequent heat waves have “resulted in tens of thousands of deaths.”
While many of those people were elderly, young people suffered, too.
As heat waves become more severe, parents and coaches “may not realize that the children are more exposed and therefore more vulnerable,” Dr. Sarfaty said.
A 2017 report that she helped prepare found that, in the United States, heat related illnesses were the leading cause of death and disability in young athletes.
This is the third time The Lancet has weighed in on the health impacts of climate change, but the first with a focus on children. “It was our contention, both negatively, that the health costs were huge and underestimated. But also, more positively, that by putting health first in our response to climate, there were dividends for both the public and for the economy in terms of cleaner and safer cities and healthier diets,” Dr. Richard Horton, editor in chief of The Lancet, said.
To that end, the report does contain glimmers of hope. Carbon intensity, or how much energy can be produced for each unit of greenhouse gas released, has increased. And more cities are filing climate assessments detailing solutions that can be put into place. But these actions are happening against a backdrop of greenhouse gas emissions that continue to rise.
A child born today will live until 2090 on average, Dr. Watts said, noting that without changes to greenhouse gas emissions the planet could warm by 4 degrees by then. “We roughly know what that looks like from a climate perspective,” he said. “We have no idea what that looks like from a public health perspective. But we know it is catastrophic.”
The report, and its focus on children, comes at a time when youth climate demonstrations including school strike protests spearheaded by Greta Thunberg, the Sunrise movement and Extinction Rebellion have attracted attention.
“This may be the first time in the history of the United States that there are children wondering whether they are going to have a future, whether they should have children as a result of the potential for climate change to get worse and worse,” Ms. McCarthy said.
This year, Jamie Margolin, the 17-year-old founder of the climate activist group Zero Hour testified before Congress. “Everyone who will walk up to me after this testimony saying I have such a bright future ahead of me, will be lying to my face,” she said. “It doesn’t matter how talented we are, how much work we put in, how many dreams we have, the reality is, my generation has been committed to a planet that is collapsing.”