As people around the world suffer through concurrent extreme heat waves, droughts and wildfires, the effects of climate change are becoming a grim, global reality.
Despite robust evidence of the environmental and economic costs of rising temperatures, far less is known about how these temperatures may be affecting the quality of people's lives.
A new analysis from Gallup -- published in collaboration with Citi -- represents the first step toward quantifying the toll that rising temperatures may have on how people rate their lives.
Every year, Gallup asks people worldwide to rate their lives through its World Poll. For this analysis, researchers examined 13 years of World Poll data on people's life evaluations using geospatial information on 1.75 million survey respondents in 160 countries and 30 years of daily high-resolution temperature data from NASA.
Gallup used the NASA data to map local temperatures in the 30 days before each survey interaction to understand how exposure to high-temperature days -- days identified as outliers to the seasonal norm -- affected people's ratings of their lives.
Given current climate projections, high-temperature days could decrease life evaluations by an estimated 17% by 2030.
The analysis paints a bleak picture of the future. Using observed heat trends from the past 14 years to predict the global rise in high-temperature days over the next decade, the results suggest people will experience, on average, 3.1 such days in 2030, compared with 1.7 days in 2021. The cumulative effect of such days implies that, holding all else constant, rising temperatures will be associated with a drop in life evaluations three times greater in 2030 than in 2020.
Rising temperatures correspond with a drop in people's wellbeing.
Each time a person experiences a high-temperature day, their life evaluation drops by an average of 0.56%. Globally, people faced three times more "high-temperature days" in 2020 than in 2008, and people's ratings of their lives dropped by 6.5%, controlling for location and other factors known to influence people's life evaluations.
This 6.5% is a meaningful decrease, considering that life evaluation has been a relatively stable measure since Gallup started tracking it. As the number of above-normal temperature days continues to grow, the analysis suggests that life ratings will continue to drop, with considerable declines in life evaluations in countries with more frequent high-temperature days.
Rising temperatures have a more obvious effect on older generations and people in poorer economies and in developing economies such as China and Brazil.
The analysis shows a more pronounced effect of rising temperatures on already-vulnerable demographic groups, namely, people aged 65 and older as well as those with lower levels of education.
Among people aged 65 and older, each day of exposure to high temperatures in the 30 days before the survey is associated with a 1.11% drop in life evaluation, versus a 0.48% drop among people younger than 65. This finding validates existing research on the vulnerability of older people to heat and how they are more likely to become sick or die from excessive heat.
The strength of the relationship between high-temperature days and life evaluation ratings also varies by educational attainment. The difference is less significant by gender, although other research suggests climate change affects women and men differently.
Among the 110 low- and middle-income countries where Gallup conducts interviewing face to face, the decline in life evaluations associated with one additional high-temperature day is 0.050 scale points, or 0.74% -- a larger effect size than in the global analysis. This finding affirms previous research showing that people in developing regions are more vulnerable to weather extremes than are those in high-income countries and territories.
Significant negative relationships were seen individually in several of the world's most populated countries, including China, Turkiye, Brazil, Nigeria and Mexico.
This analysis represents the first step in understanding the effects of rising temperatures on global populations and, more specifically, on vulnerable communities. The implications of these findings are alarming. Experts say the climate crisis will increase the frequency and intensity of extreme weather events, including heat waves. As climate effects compound, declines in life evaluation could foreshadow increased food insecurity, migration, conflict and declines in mental health.
To evolve how policymakers and their constituents think about the issue of climate change, stakeholders need clear evidence of where and how weather changes could affect people's everyday lives. This analysis is a crucial step toward a more complete and accurate view of the true impact of climate change on people's lives.
It is also a novel attempt to explore the relationship between rising temperatures and life evaluations. Yet, the relationships and associations mentioned do not imply causality. Human adaptation to and recovery from rising temperatures needs to be considered in future research. More research is also needed to explore the mechanism through which climate change affects people's livelihoods.