As global temperatures rise, a quiet transition to inactivity could accelerate deaths and economic losses, especially in the world’s most vulnerable regions.
study: The impact of climate change on physical inactivity: A panel data study across 156 countries from 2000 to 2022. Image credit: ChameleonsEye/Shutterstock.com
Climate change is increasing global heat exposure, but its impact on physical inactivity has received little attention. In recent modeling studies, lancet Researchers predict that physical inactivity could increase by up to 1.75 percentage points, particularly in low- and middle-income regions in the tropics, and that high-emissions scenarios could result in up to 700,000 additional deaths per year by 2050.
Rising global heat reshapes physical activity patterns
Physical inactivity is a major cause of poor cardiometabolic health. It is thought to be responsible for 5% of adult deaths, accounts for $54 billion in health care costs, and is responsible for $14 billion worth of lost productivity.
Approximately one-third of the world’s population is sedentary and does not meet the World Health Organization (WHO) physical activity guidelines. As global temperatures rise, physical activity increases the strain on the cardiovascular system, making it feel more demanding. Additionally, as extreme weather events become more common and air quality worsens, safe physical activity may become more difficult.
This is evidenced by a 28% increase in the risk of moderate or severe heat stress from light physical activity in 2023 compared to 1990-1999. Experts predict that at temperatures 2 degrees Celsius above pre-industrial temperatures, more than a quarter of the world’s people could experience an additional month of severe heat stress than they did from 1950 to 1979. This limits the time available for physical activity.
Increased climate change-related deaths from non-communicable diseases are already disproportionately impacting low- and middle-income countries (LMICs). This study aimed to assess longitudinally how temperature affects physical inactivity over 20 years and to predict future health and economic costs if such trends continue under different climate scenarios.
Global analysis predicts future inactivity and economic burden
Researchers looked at thousands of observations linking temperature and physical inactivity across a panel of 156 countries from 2000 to 2022. This made it possible to estimate how heat exposure is associated with changes in physical activity while controlling for the influence of socio-economic and environmental factors.
This was combined with projected changes in temperature to project changes in physical inactivity rates to 2050, considering socio-economic parameters across multiple common socio-economic pathway scenarios. Finally, these were converted into health and economic costs using country-specific economic and labor participation indicators.
Rising temperatures lead to deaths and reduced productivity
Initial baseline analyzes show that more than 25% of the world’s population is physically inactive, more women than men. The average annual temperature was 19.2°C, with a wide range from below freezing to over 28°C.
Similarly, physical activity was widespread, but broadly related to climate. Still, physical activity rates were higher in some colder regions, such as North America and Argentina.
The model predicted a 1.44 percentage point increase in physical inactivity globally for each additional month with temperatures above 27.8 °C, highlighting the nonlinear relationship with concentrated impacts above this threshold. This effect may be particularly pronounced in women and older adults, as previous studies have shown that heat compensation mechanisms such as sweating are less efficient in women and older adults.
Adjusting for income, we find that increased inactivity due to climate change primarily targets small and medium-sized countries. Inactivity was estimated to increase by 1.85 percentage points in LMICs compared to minimal or nonsignificant changes in high-income countries. There were several hotspots that were most affected. These include Central America, the Caribbean, eastern sub-Saharan Africa, and equatorial Southeast Asia. These trends were consistent in further subgroup analyses.
The model also showed that at this level of heat exposure, the estimated additional deaths could range from 0.47 million to 0.70 million per year by 2050. Moreover, in the projected scenario, productivity losses could reach between 2.400 and 368.0 billion USD.
This corresponds to approximately 7-11% of deaths and up to 7.9% of productivity losses in 2022 due to inactivity. Again, economic losses will primarily affect small and medium-sized enterprises. The projected increase in all-cause mortality due to physical inactivity will also remain low across developed countries, but will be most pronounced in LMICs.
The authors point out that this will perpetuate and exacerbate existing inequalities, as most workers in LMICs have to work during hot hours. Another global labor forecast predicts that around 5% of working hours will be lost in the world’s hottest regions due to heat stress.
Meanwhile, climate-controlled spaces are largely out of reach in these regions, especially for disadvantaged groups such as women. Furthermore, it is difficult to incorporate the rising prevalence of cardiometabolic diseases into public health budgets in these countries.
The authors suggest urgent mitigation measures should be taken, including improved urban design to cool cities and encourage physical movement. This could include access to connected shaded walkways, reflective and thermally permeable surfaces, more water features, and affordable climate-controlled athletic facilities.
Health policies should also incorporate public education about the heat risks of different types and intensities of physical activity and promote adaptation strategies for safe activity in hot climates.
Research limitations
Despite careful data analysis, several limitations must be considered. Physical activity estimates are based on self-reported data, which can introduce recall and social desirability biases. Using national annual data limited our ability to account for seasonal variations and age-specific patterns. The study also did not differentiate between types of physical activity, such as voluntary and forced activities, which can blur behavioral differences.
Additionally, this analysis does not account for changes in urbanization or migration over time, which may weaken exposure comparisons. Socioeconomic and health indicators were measured at the country level, so within-country confounding may remain. Finally, extreme weather events that could influence predicted physical inactivity rates were not included in the modeling.
Inactivity due to climate change threatens health and economic stability
This finding has important implications for changes in climate-induced inactivity that will slow economic growth and ultimately lead to more deaths.
Treating physical activity as a climate-sensitive necessity rather than a discretionary lifestyle choice is essential to prevent heat-induced sedentary transition and the associated surge in cardiometabolic diseases and economic losses.
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