Heatwave deaths in the UK are set to soar if nothing is done to curb greenhouse gas emissions, research has shown.
Scientists estimated an average of 540 people dying per year in the UK as a result of heatwaves between 1971 and 2020.
With unrestricted emissions, that figure was expected to quadruple to 2,160 in the period 2031 to 2080.
Even with global warming pegged to below 2C above pre-industrial levels, the annual number of heatwave deaths was still expected to double between the two periods.
Heatwaves can kill in a range of different ways, chiefly by aggravating lung and cardiovascular conditions.
In severe cases heat stroke, which occurs when body temperature rises above 40C, proves lethally damaging to the brain and other organs.
The new study is the first to predict future rates of heatwave death around the world as a result of global warming.
The UK was one of 20 countries included in the research, published in the journal Public Library of Science Medicine.
Computer simulations were run to project excess mortality linked to heatwaves, taking into account different levels of greenhouse gas emissions, population density and the ability of populations to adapt to hotter conditions.
Study author Dr Antonio Gasparrini, from the London School of Hygiene & Tropical Medicine, said: “Several countries around the globe are currently experiencing deadly heatwaves which, since 2000, have thought to have been responsible for tens of thousands of deaths, including the regions of Europe and Russia.
“It is highly likely that there will be an increase in heatwave frequency and severity under a changing climate, however, evidence about the impacts on mortality at a global scale is limited.
“This research, the largest epidemiological study on the projected impacts of heatwaves under global warming, suggests that climate change could dramatically increase heatwave-related mortality, especially in highly-populated tropical and sub-tropical countries.”
He said the “good news” was that loss of life would be greatly reduced under scenarios that met the Paris Agreement target of limiting the post-industrial rise in global temperature to 1.5C.
Columbia faced the biggest threat from heatwave deaths, according to the research – a potential increase of 2,000% between the two periods studied.
The Philippines and Brazil were the next two most vulnerable countries.
Lead scientist Dr Yuming Guo, from Monash University in Australia, said: “Future heatwaves .. will be more frequent, more intense and will last much longer.
“If we cannot find a way to mitigate climate change and help people adapt to heatwaves, there will likely be a big increase of heatwave-related deaths in the future, particularly in the poor countries located around the equator.”
The scientists recommended a number of measures to reduce the impact of health waves, including better urban planning and housing, planting trees, and ensuring public access to drinking water.