A sharp surge in deaths is forecast without action to combat climate change, warns the biggest global study into the harmful effects from shifting temperatures.
As the world heats up, scientists predict drastically more people will die because of hot weather, with the warmest, most crowded and poorest countries hardest hit.
But capping emissions and stopping global warming getting worse could prevent such rising mortality rates, said the report out today in medical journal, The Lancet Planetary Health.
With climate change now widely recognised as the biggest global threat of the 21st century, previous studies have shown a potential rise in heat-related mortality. But until now, little was known about how much the increase would be balanced out by a fall in cold-related deaths.
"A fast change in political, policy and public attitude is needed, in order that some of these impacts are avoided in the future," said co-author Dr Ariana Zeka at Brunel University London.
Global temperature rises are expected with climate change, she said. "But predictions also suggest that frequency and severity of temperature changes are to increase."
Without action, by 2090-99, the study said south-east Asia will see deaths rise by 12.7 per cent. Deaths in southern Europe will climb by 6.4% and 4·6% in South America. Meanwhile, cooler regions such as Northern Europe could experience either no change or a minor drop in deaths. And Dr Zeka highlights: "Some of these regions are already under direct or indirect impacts of climate change through water resources, coastal areas, land and forest environmental changes."
These deaths could largely be avoided by moves to cut greenhouse gas emissions, said the study, which compared heat- and cold-related deaths across 451 locations.
"The good news is that if we take action to reduce global warming," said study leader, Dr Antonio Gasparrini, from the London School of Hygiene & Tropical Medicine. "For instance, by complying with the thresholds set by the Paris Agreement, this impact will be much lower."
The figures are from the first global model of how hot and cold temperatures change death rates. The model is based on real data from 85 million deaths between 1984 and 2015 and takes into account different countries, climates and economies.
Cutting carbon dioxide emissions and pollutants such as methane and black carbon could quickly bring major health benefits, the study also notes by reducing deaths from air pollution.
"The findings will be crucial for the development of coordinated and evidence-based climate and public health policies," added Prof Gasparrini. "And for informing the international discussion on the health impacts of climate change vital for the future health of humanity."
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