Rising temperatures are leading to increased levels of stress, worsening anxiety and depression, and even suicide in the most extreme cases in Australia.
Scientists have identified for the first time an association between mean annual maximum temperatures pushed higher by climate change and suicides for both males and females across states and territories, according to a paper published by The Medical Journal of Australia on Thursday.
“In Australia, hot days have a damaging effect on [the] whole population equivalent to that of unemployment and predict hospitalisation for self-harm,” according to the paper.
“It’s quite a revelation,” said Paul Beggs, an associate professor at Macquarie University and one of the report’s authors. “It’s not been found before.”
As with losing one’s job, heatwaves have a wide range of effects on people, including adding stress and worsening anxiety and depression, he said, adding extreme heat was just one aspect of how climate change was damaging human health.
Those effects were given a global perspective in a wider paper on the issue by The Lancet journal, with the publication finding 157 million more people were exposed to heatwave events in 2017 compared with 2000. On average, those affected were hit by 1.4 more heatwave days annually.
The Lancet noted even small changes in temperature and precipitation results in large changes in the suitability of vector-borne and water-borne diseases, such as dengue and cholera.
In 2016, for instance, highlands of sub-Saharan Africa had an increase in more than a quarter in the capacity for the transmission of malaria compared with 1950.
In Australia, dengue fever was one example of a climate-sensitive disease that was spreading as temperatures rise. “It’s increasing steadily as time goes on,” Professor Beggs said, with the tropics expanding.
Food insecurity would likely increase globally as a warmer climate with more erratic rainfall reduces the yield of key agricultural crops, The Lancet paper found. Crop yields were now falling in 30 nations, reversing a decades-long trend.
“[F]ood production is already being compromised by extremes of weather that are predicted to become more frequent and extreme,” the paper said. Those deleterious effects “outweigh potential positive impacts on national nutrition and food security through varietal breeding, improved farming practices and reductions in poverty”.
Both papers stressed the need to decarbonise economies to reduce the main driver of climate change, the burning of fossil fuels.
The Lancet paper noted cutting coal-fired power plants and other sources of greenhouse gases such as cars would also have important health co-benefits.
In 2015, fine particulate matter was responsible for an estimated 2.9 million premature deaths, with coal responsible for more than 460,000 of them, it said.
Anthony Capon, professor of Planetary Health at the University of Sydney, said that as Australia was responsible for about 7 per cent of world coal output – mostly exported – our share could be in the order of 35,000 premature deaths annually.
“Every time our ships leave our ports laden with coal, we’re exporting the health-harm of that coal,” Professor Capon said.
A spokesman with the Minerals Council said Australian coal had “powered the industrialisation of Japan, Korea and China, directly contributing to hundreds of millions of people being lifted out of poverty and improving the living standards for many more”.
He noted that the International Energy Agency’s latest World Energy Outlook found coal will remain the single largest source of electricity through to 2040 under both the current and new policies scenarios, as Asian nations continue to urbanise and their economies expand.
“The focus by the coal sector will be on how to lower its emission profile through more innovation and carbon capture and storage,” he said.