A report published Wednesday in medical journal The Lancet warns that the human-caused climate crisis is already disproportionately affecting children worldwide and "will define the health profile of current and future generations" if left unabated.

"With warming temperatures, a child born today faces a future where their health and well-being will be increasingly threatened."

—Dr. Renee N. Salas, Harvard

The report is a project of The Lancet Countdown: Tracking Progress on Health and Climate Change, an international, multidisciplinary collaboration between academic institutions that formed four years ago and releases annual reports.

Nick Watts, executive director of The Lancet Countdown, said on a call with reporters: "To the extent that we're asking, well, how is it different from before to the life of a child born today? That child now is being born for the first time into a world where their health will be affected at every single stage of their life by a changing climate."

Watts explained in a statement that "children are particularly vulnerable to the health risks of a changing climate" because "their bodies and immune systems are still developing, leaving them more susceptible to disease and environmental pollutants."

"The damage done in early childhood is persistent and pervasive, with health consequences lasting for a lifetime," he added. "Without immediate action from all countries to cut greenhouse gas emissions, gains in well-being and life expectancy will be compromised."

#ClimateAction could be “the greatest global health opportunity of the 21st century” - a key conclusion of the 2019 @LancetCountdown report, a study which sheds light on the impacts of #climatechange on human health. #COP25 https://t.co/pDaNGFLifR pic.twitter.com/2Ke8Q2FitB — UN Climate Change (@UNFCCC) November 14, 2019

Despite some efforts around the world to transition away from fossil fuels and curb greenhouse gas emissions, "the current progress is inadequate," says the new report. "Bold new approaches to policymaking, research, and business are needed in order to change course. An unprecedented challenge demands an unprecedented response, and it will take the work of the 7.5 billion people currently alive to ensure that the health of a child born today is not defined by a changing climate."

Alongside the report, The Lancet released a short video detailing the report's key findings and recommendations:

"There are many paths we can take, from a world of extremes and uncertainty, where a child has to fight simply to survive, to an environment that creates the conditions that allows them to thrive," the video says. "If we continue down our current path, a child born today will live through a world that is over 4°C warmer, with a changing environment threatening the food they eat, the air they breathe, and the communities they grow up in."

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, said in a statement Wednesday: "With warming temperatures, a child born today faces a future where their health and well-being will be increasingly threatened. Climate change, and the air pollution from fossil fuels that are driving it, threaten a child's health starting in their mother's womb and it only accumulates from there."

The report highlights how, in a world that fails to limit temperature rise, not only will air pollution damage children's hearts and lungs over their lifetimes, but crop failure will cause increased food insecurity that leads to more malnutrition. Summarizing the report's warnings for children, the video says, "throughout their adult lives, they will experience more heatwaves, stronger storms, the spread of infectious disease, and see climate change intensify mass migration, extreme poverty, and mental illness."

"There are...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.” - NRDC's incoming president Gina McCarthy #LancetClimate19 https://t.co/dypV9p5ujX — NRDC (@NRDC) November 14, 2019

"But the future doesn't have to look this way," the video notes, laying out a path forward that features wind and solar energy systems, "cycle ways and green spaces supporting safer and more livable cities," and a world with net-zero GHG emissions.

Referencing the 2015 Paris climate agreement's goal of "keeping a global temperature rise this century well below 2°C," the report says:

In a world that matches this ambition, a child born today would see the phase-out of all coal in the U.K. and Canada by their sixth and 11th birthday; they would see France ban the sale of petrol and diesel cars by their 21st birthday; and they would be 31 years old by the time the world reaches net-zero in 2050, with the U.K.'s recent commitment to reach this goal one of many to come. The changes seen in this alternate pathway could result in cleaner air, safer cities, and more nutritious food, coupled with renewed investment in health systems and vital infrastructure.

Gina McCarthy, who led the Environmental Protection Agency during the Obama administration and was not involved in the report, told Vox that "the mitigation and adaptation recommendations in the report are something that I think people should focus attention on, because I want them to know that climate change isn't a lost cause... Health and climate are not unrelated issues; they are directly related."

The U.S. policy brief (pdf), authored by Salas and two colleagues, also includes key recommendations for policymakers to mitigate and adapt to climate change:

Rapidly reduce GHG emissions: Policymakers at all levels of government and across all sectors must ensure reductions in GHG emissions that far surpass the existing Paris Agreement commitments and align with IPCC recommendations.

Policymakers at all levels of government and across all sectors must ensure reductions in GHG emissions that far surpass the existing Paris Agreement commitments and align with IPCC recommendations. Commit to decarbonization: Policymakers should adopt legislation and regulatory action that supports rapid transition of electricity generation away from fossil fuels and reduces emissions from the transportation sector. This would follow the precedent set by the ten states and the District of Columbia that have announced a 100% clean or renewable electricity goal, and the 14 states and the District of Columbia that have enacted low-emission vehicle standards (as of October 2019).

Policymakers should adopt legislation and regulatory action that supports rapid transition of electricity generation away from fossil fuels and reduces emissions from the transportation sector. This would follow the precedent set by the ten states and the District of Columbia that have announced a 100% clean or renewable electricity goal, and the 14 states and the District of Columbia that have enacted low-emission vehicle standards (as of October 2019). Enable healthier lifestyles to reduce carbon emissions: Policymakers should invest in infrastructure that supports active travel like biking and walking. Interventions to facilitate active travel simultaneously decrease emissions of GHGs and air pollution, while also promoting physical activity and offering multiple benefits for health.

Policymakers should invest in infrastructure that supports active travel like biking and walking. Interventions to facilitate active travel simultaneously decrease emissions of GHGs and air pollution, while also promoting physical activity and offering multiple benefits for health. Invest in evidence-based adaptation and improved surveillance: Federal, state, and local governments should invest further in evidence and monitoring to guide health protection strategies, including surveillance of the health impacts of climate change and efforts to improve understanding of how future climate trends are likely to impact health.

Federal, state, and local governments should invest further in evidence and monitoring to guide health protection strategies, including surveillance of the health impacts of climate change and efforts to improve understanding of how future climate trends are likely to impact health. Increase resilience by strengthening health systems: Federal and state agencies should minimize climate-related disruptions to public health and healthcare systems through improvements such as resilient infrastructure, emergency preparedness, and supply chain resilience.

"We are hurtling towards a world that is climatically more dangerous than the one we grew up in," Salas said Wednesday, "and we have a profound responsibility to implement the treatment—a swift and urgent reduction in greenhouse gas emissions, for the sake of every child in our life."

As the report points out, the new findings come as children across the globe are increasingly rising up to demand a habitable future. Following a pair of youth-led global climate strikes in September that brought millions of people into the streets, young activists are now planning two more climate strikes—on Nov. 29 and Dec. 6—to coincide with the COP25 climate summit in Madrid.