Elderly More Vulnerable To Heatwaves Than Previously Thought, Study Finds

Older people could face a far greater threat from extreme heat caused by climate change than previously estimated, according to a new US modelling study published in The Lancet Planetary Health.

The study was released as the northern hemisphere experiences another summer of record-breaking temperatures, with prolonged heatwaves linked to tens of thousands of deaths. Researchers led by scientists at Stanford University examined how frequently rising global temperatures could reach levels that older adults are unable to tolerate.

Existing Heat Thresholds May Underestimate Risk

Scientists have traditionally used wet-bulb temperature to assess the danger posed by extreme heat. The measure combines temperature and humidity to determine when the human body can no longer cool itself effectively. However, previous experiments used to establish these thresholds largely involved young, healthy adults. According to the researchers, that approach overlooks the greater vulnerability of older people.

Ageing can reduce the body’s ability to sweat and cool itself, while older adults are also more likely to have cardiovascular problems and other underlying conditions that can increase the effects of extreme heat.

The researchers therefore incorporated findings from newer wet-bulb experiments in the US involving people over 60. They combined the results with population-ageing projections to estimate heat exposure among three age groups through 2100 under different warming scenarios.

The findings suggested that dangerous heat will affect more people and last longer than earlier estimates indicated.

22% Of Older Adults Could Face Unsafe Heat

Under a scenario in which global temperatures rise 1.5°C above pre-industrial levels, the researchers estimated that 22% of people aged over 60 worldwide could be exposed to unsafe heat for at least one month every year. Each additional degree of warming could result in around one billion more people experiencing approximately another month of heat and humidity beyond what their bodies can tolerate.

At 3°C of warming, older people in some of the world’s most vulnerable regions, including South Asia and the Gulf, could experience dangerous heat continuously during the day and night for up to three months each year.

India, Pakistan, Bangladesh, Myanmar and Niger were among the countries identified as facing particularly high risks due to extreme heat, poverty and limited access to cooling.

Heat Could Fuel Climate Migration

The researchers warned that the growing threat of intolerable heat could have major social and humanitarian consequences. Increasing exposure could drive people to move within their own countries or across international borders, adding to the challenges associated with climate migration.

The study called for stronger action to reduce greenhouse gas emissions and limit global warming. It also urged authorities to put older adults and other vulnerable groups at the centre of heatwave preparedness plans.

Access to cooling could be particularly important. The researchers noted that many heat-related deaths occur indoors, highlighting the need for wider access to air conditioning and other cooling measures.

The findings arrive amid a summer marked by severe heatwaves, drought and wildfires across Europe. With global temperatures continuing to rise, the researchers said protecting ageing populations will become increasingly important as extreme heat becomes more frequent and persistent.