Global warming will take a toll on children's health, according to a new report showing hospital admissions for fever soar as days get hotter.
The new study found that temperature rises had a significant impact on the number of pre-schoolers presenting to emergency departments for fever and gastroenteritis.
The two-year study at a major children's hospital showed that for every five-degree rise in temperature two more children under six years old were admitted with fever to that hospital.
The University of Sydney research is the first to make a solid link between climate changes and childhood illness.
"And now global warming is becoming more apparent, it is highly likely an increasing number of young children will be turning up at hospital departments with these kinds of common illnesses,' said researcher Lawrence Lam, a paediatrics specialist.
"It really demonstrates the urgent need for a more thorough investigation into how exactly climate change will affect health in childhood.'
Dr Lam said the results, collated from The Children's Hospital at Westmead admissions, back up beliefs that children are less able to regulate their bodies against climate change than adults.
The brain's thermal regulation mechanism is not as well developed in children, making them more susceptible to "overheating' and at risk of developing illness, he said.
"They're particularly at risk of extreme changes, much more than other people.'
The study, published in the International Journal of Environmental Health Research, analysed several different climate factors, including UV index, rainfall and humidity, collected from the Bureau of Meteorology in 2001 and 2002.
Temperatures were the only negative risk factor, with findings linking heat to both fever and gastro disease but not to respiratory conditions.
Surprisingly, rates of gastroenteritis were lower on days with a high UV factor probably, says Dr Lam, because the rays "sterilised' the ground, killing more germs and reducing risk.
He said it was still unclear whether the heat directly triggered the illnesses or whether other heat-related problems, like pollution, were responsible.
A longer-term study was needed add strength to the findings, Dr Lam said.