Higher risk of temperature-related death if global warming exceeds 2°C

The death rate linked to extreme temperatures will significantly increase under global warming of 2°C, finds researchers from UCL and the University of Reading.

Temperature-related mortality – where a death is directly linked to climate temperature – in England and Wales during the hottest days of the year will increase by 42% under a warming scenario of 2°C from pre-industrial levels.

This means an increase from current levels of around 117 deaths per day, averaged over the hottest 10 days of the year, to around 166 deaths per day.

At current global warming levels of around 1.21°C, we see a slight decrease in temperature-related mortality in winter and a minimal net effect in summer, meaning that overall, at this level of warming we see a slight decrease in temperature-related mortality rate.

In the paper, published in Environmental Research Letters, the researchers found that as the global mean temperature increases temperature-related mortality in summer will increase at a much faster, non-linear rate.

The rate of increase particularly speeds up at 2°C of warming, with a much higher risk appearing beyond 2.5°C. The researchers say that 3°C warming could lead to a 75% increase in mortality risk during heatwaves.

The findings underline the importance of keeping global warming levels to below 2°C.

Lead author Dr Katty Huang, UCL Civil, Environmental & Geomatic Engineering, said: ‘The increase in mortality risk under current warming levels is mainly notable during heatwaves, but with further warming, we would see risk rise on average summer days in addition to escalating risks during heatwaves. What this means is that we shouldn’t expect past trends of impact per degree of warming to apply in the future. One degree of global warming beyond 2°C would have a much more severe impact on health in England and Wales than one degree warming from pre-industrial levels, with implications for how the NHS can cope.’

Project lead Professor Andrew Charlton-Perez, University of Reading, commented: ‘As the Intergovernmental Panel on Climate Change impacts report recently showed, it is increasingly common to examine how different levels of mean global warming raise the risk of significant harm to people and society. Our study shows that because death rates will go up significantly if countries experience very high temperatures, limiting the average global rise in temperatures is likely to have substantial benefits for the overall health of the population.’

Photo by Avi Theret