Heat-related deaths climbed 117% over 25 years

What they found: Deaths in which heat was an underlying or contributing cause varied year-to-year from 1999 to 2016 before showing steady increases over the last seven years observed.

• Annual deaths peaked at 2,325 last year, when numerous climate records were shattered and the global climate was the hottest seen in at least 125,000 years.
• When accounting for differences in age, average mortality due to the heat rose 3.6% a year over the 25 years studied, falling 1.4% between 1999 and 2016 before surging 16.8% annually from 2016 on.
• Mortality rates may have been understated because heat's effects aren't always noted on death certificates.

Context: Heat-related illness develops when the body can't sufficiently cool itself or when its temperature exceeds 106°F, at which point organs can shut down and people can become permanently disabled.

• The International Labor Organization this year estimated that workers suffer 22.85 million occupational injuries and 18,970 work-related deaths from excessive heat every year globally.

• Older adults and other people who are isolated or have poor mobility are also more likely to experience the health effects of extreme heat.
• Infants and children are also at risk, along with pregnant women, who could suffer miscarriages, premature births and other complications.

What's next: 2024 is on a pace to come close or even exceed 2023's record temperatures, which could extend the trend of heat-related deaths.

• More attention is being focused on addressing "urban heat islands" where buildings and other development trap heat and where residents often are poorer and lack trees and plants that can help cool an area.