But it makes clear that urgent action to stop global warming would dramatically improve children's life chances, a Sky News report said.
Dr Nick Watts, executive director of The Lancet Countdown On Health And Climate Change, told Sky News "At the global level, if we continue on the current trajectory, climate change comes close to wiping out the last 50 years of gains we have seen in public health.
"We are not just worried about heatwaves and what they do through heart disease or kidney disease.
"And we are not just worried about malnutrition.
"We are worried about what happens to a community, to a population, to a child born today, when they are hit again and again from multiple different angles.
"That has a lifelong impact."
The report warns that rising temperatures will increase the spread of diseases such as mosquito-borne dengue fever and highly infectious diarrhoea caused by Vibrio bacteria, reduce yields for staple crops such as wheat, rice and maize by 4-6 per cent while the world's population soars, increase the risk of malnutrition and price rises, intensify heatwaves, with deaths from extreme temperatures in the UK rising from 2,000 to 7,000 a year by the 2050s.
It also warns there will be a rise in post-traumatic stress disorder caused by severe flooding.