(CNN)When Aaron Bernstein became a pediatrician 15 years ago, it didn't occur to him that the climate crisis would grow into a critical health problem for his young patients.
But over the years he started to notice more children visiting emergency rooms for heat-related illnesses, and some even suffered from climate-induced mental health issues.
"Almost nobody was considering climate change a health problem at the time," Bernstein, the interim director of the Center for Climate, Health, and the Global Environment at Harvard T.H. Chan School of Public Health, told CNN. "I feel like a total idiot for not seeing it earlier, because we could have been more ahead of this than we have been."
On Wednesday, the New England Journal of Medicine, which Bernstein called the "holy grail" of all medical journals, published a comprehensive review of the science to-date and concluded that the effects of burning fossil fuels — things like air pollution, severe weather, poor water quality and extreme heat — pose a significant and growing risk to the health of babies and children.
Frederica Perera, lead author of the review and the founding director of the Columbia Center for Children's Environmental Health at Columbia University, said the purpose of the study was to not only show the link between the planet's heavy reliance on fossil fuels and children's health, but to also point out the available solutions that could prevent climate change-fueled disasters from putting the world's youngest people at risk.
"We've been seeing this whole range of [climate] effects that are sending children to the ER, and the list goes on, so I decided to put it all together," Perera told CNN. "In a way, this is bad news, but look, we know how to deal with this. We know how to bring down emissions. We can take action now to make a huge difference, and that was the purpose of the article."
Although the paper outlines several extreme climate events including flooding as well as air pollution, researchers say that heat remains the deadliest of all natural disasters in the US and that it poses a unique response situation.
"Heat is sneaky," said Bernstein, who was not involved with the review. And because the impacts of heat can go unnoticed, Perera said it's easy for parents or adult guardians — who have the ability to regulate their body temperatures better than kids — to overlook some symptoms when a child is suffering some heat-related condition.
The paper comes as extreme heat warnings have been issued for millions of people in the Southeast and Midwest.
Experts have noted for years that the most vulnerable populations, including children and pregnant women, are at highest risk to heat-related illness like heat stroke.
"Children are dependent on adults for care and for receiving enough fluids and being placed in a cool place, making them particularly vulnerable," Perera said. "We've seen tragic instances of children dying in parked cars during heat waves, where parents haven't understood how hot it is."
In January, Bernstein published a study that found that simply having been exposed to extreme heat increased the likelihood that a child would need to visit the emergency room for any reason in the summer, even on days when temperatures weren't the hottest. Because of the climate crisis, a child born in the US today will experience 35 times more life-threatening extreme heat events than one born about 60 years ago, Bernstein's research showed.
"We know more than enough to recognize heat as a major risk to child health," Bernstein said. "We have evidence that children are showing up in emergency departments for all kids of problems when it gets hot out; that women who are pregnant and exposed to heat may have worse birth outcomes; and that heat affects children's ability to learn and perform well on exams."
And as parts of the world continue to ramp up fossil fuel production, which will worsen the already accelerating crisis, Perera said she hopes the paper would motivate physicians and healthcare providers, who are a "trusted voice" around the world, to take on a larger role in advocating for climate policies to protect children from a warming planet.
"The clock is ticking," she said. "We probably have less time because of the very sharp upward trajectory in emissions and temperatures, but there is a lot we can do to help children and families adapt to the already existing conditions brought by the changing climate."
Correction: This story has been updated to correct how long Aaron Bernstein has been in the field of pediatrics.