Even the Same Heat Is More Dangerous for the Elderly... 290 Million at Risk with 1.5°C Rise [Reading Science]

Heatwave Risks Previously Calculated for Young Adults —
Danger Zone Population More Than Doubles When Age Is Considered
"South Korea Faces Overlapping Challenges of Aging and Tropical Nights...
Age-Based Heatwave Response Measures Needed"

A new study has found that if the global average temperature rises by 1.5°C above pre-industrial levels, more than one in five elderly people worldwide could be exposed to heat intense enough to be intolerable for humans for at least one month each year.

Existing assessments of heat wave risks have traditionally applied the heat tolerance levels of healthy young adults to all age groups. This means that temperatures previously considered “tolerable” may already be dangerous for the elderly.

A day before Ipchu, the solar term marking the beginning of autumn, on the 6th, a farmer is resting after removing weeds under the scorching sun in a rice field in Okpo-eup, Dalseong-gun, Daegu. Photo by Yonhap News

According to research by an international team including Stanford University, published on August 18 in the journal 'The Lancet Planetary Health,' if global warming reaches 1.5°C, it is estimated that about 290 million people aged 60 and over—representing 22% of the global elderly population—will be exposed to dangerous heat levels for at least one month every year.

This mirrors the level of heat risk young adults would face if global warming increased by 4°C. If the warming reaches 3°C, elderly populations in some regions could experience extreme heat for more than three months each year.

The research team incorporated existing experimental data into global climate and population projections, reflecting that heat tolerance thresholds differ for young adults (aged 15–39), middle-aged adults (aged 40–59), and the elderly (aged 60+). Older people have a reduced ability to regulate body temperature through sweating and slower vascular responses, which means their body temperature can rise more quickly than in younger adults even at the same temperature and humidity.

Applying heat tolerance standards by age group, the global population exposed to extreme heat for over 180 hours annually more than doubled compared to previous estimates. The danger was especially pronounced in South Asia and the Persian Gulf region.

Super-aged South Korea also faces risks..."Humidity and tropical nights must be considered alongside temperature"

South Korea is no exception. Seung-Sik Hwang, professor at Seoul National University Graduate School of Public Health, stated, "Korea is entering a super-aged society more rapidly than any other country in the world. The study also identifies Korea as a country where a significant portion of the elderly will be exposed to dangerous heat for more than 180 hours a year if warming reaches 3°C." He added, "This research quantitatively demonstrates that climate risk essentially translates to aging risk."

He particularly pointed out the limitations of assessing heat wave risks solely based on maximum temperatures. Jong-Seong Kug, professor at Seoul National University Department of Earth and Environmental Sciences, explained, "In Korea, climate change is expected to greatly increase not just the frequency and duration of heat waves, but also the occurrence of tropical nights. Due to high humidity in summer, the actual heat stress people feel can be much greater, even at the same temperature."

On the evening of the 12th of last month, when the tropical night alert was issued throughout Seoul, tourists and citizens visiting Cheonggyecheon in Seoul were cooling off from the heat. Photo by Yonhap News

Addressing nighttime heat waves is also highlighted as a challenge. Jongwon Lee, professor at Keimyung University’s Department of Architecture, commented, "The analysis showed that as warming progresses, nighttime heat risk exposure among the elderly will become common in all the cities examined, except Houston in the United States. Rather than focusing only on increasing the number of cooling centers, we need to discuss where and how to provide facilities that remain open at night."

However, caution is advised when directly applying these research results to Korea. The heat tolerance criteria used in the study were mainly derived from experiments with participants in mid-latitude regions who were not sufficiently acclimatized to heat, and did not fully account for urban heat island effects and actual indoor environments.

Professor Hwang stated, "The direction of the findings is solid, but the uncertainty around the absolute figures is significant. It is urgent to establish age-specific heatwave response standards that take into account outdoor work by elderly farmers and exposure to tropical nights, as well as to ensure vulnerable seniors have access to air conditioning."

This content was produced with the assistance of AI translation services.