At a Glance
The Finding: A study led by economist Bobby Harris at Georgia Tech's Ivan Allen College of Liberal Arts reveals climate change could increase average U.S. physical activity by 893 steps per day by 2099 as people adapt to rising temperatures.
By the Numbers: Fitbit data used in Harris’ study show that warm-climate residents are 50% less sensitive to heat extremes than northern neighbors, cutting 354 steps on hot days compared to 1,081 in cooler regions.
Expert Insight: "There are still significant dangers to rising temperatures, but we must better factor adaptive capacity into conversations about climate change,” Harris said.
Hardly anyone loves exercising in the festering crucible of a brutal summer heatwave. So it stands to reason that as global temperatures rise, the kind of physical activity that’s so crucial for our health and economic productivity could fall.
But recent research from Georgia Tech’s School of Economics in the Ivan Allen College of Liberal Arts suggests adding an asterisk to earlier research that makes that conclusion, saying previous studies failed to account for one simple fact: people adapt.
Georgia Tech economist Bobby Harris used a massive database of Fitbit step count data to measure how temperature shapes physical activity and found that extreme heat cuts step counts by 6% when compared to ideal weather. And while residents of the warmest regions cut their activity by an average of only 354 steps on days over 100 degrees, those living in the coldest regions cut theirs by 1,081, according to Harris’ analysis.
To be fair, cold bites, too. On days that stay below freezing, people take roughly 1,000 fewer steps. That’s a 12% drop, enough to pack on a pound over the course of a typical Madison, Wisconsin winter, Harris found.
But as the climate grows warmer, how humanity will respond to warmer temperatures remains a significant concern. In fact, earlier research projected that, by 2050, temperature-driven declines in physical activity could contribute to 500,000 premature deaths a year worldwide and annual productivity losses topping $2.4 billion.
Projections like those typically assume everyone responds to heat the same way, with no capacity to adapt, Harris said.
How will a warming climate affect physical activity?
To assess the likelihood of people adapting to hotter climates as the planet heats, Harris compared responses across U.S. climate regions. He found that people living in the hottest parts of the country, such as Georgia, are only half as responsive to heat extremes when compared to those living in more moderate climates and only one third as responsive as those living in colder climates, such as Chicago or Minneapolis. Cold-climate residents are, in turn, far less fazed by freezing days than residents of warmer climates.
If today’s behavior patterns persist, Harris’ modeling shows climate change would barely budge average U.S. activity by century’s end as losses from hotter summers and gains from milder winters roughly cancel out nationwide.
But when his model allowed people to adapt to their future climates the way today’s warm places already have, average daily step counts rose by 893 steps per day across the country by 2099.
“If people in traditionally hotter locales are able to find ways to tolerate higher temperatures and keep moving, then there’s reason to believe people in more moderate climates will be able to adapt to some degree, as well,” Harris said. “There are still significant costs and dangers to rising temperatures, but this study does suggest that we need to better factor adaptive capacity into conversations about climate change.”
What do policymakers need to know about climate change and activity?
The biggest question mark hangs over places that are already hot, such as the American South. The study shows residents there are already better adapted to heat than their northern neighbors, and the model projects large activity gains for the region. But those projections assume Southerners can keep adapting as temperatures climb beyond anything in today's data — an assumption Harris couldn't test, because there is no hotter U.S. region to learn from.
But the modeling clearly depicts the need for more consideration of adaptation as policymakers think about the serious ways in which climate change is likely to affect their communities, Harris said.
“Understanding how we will react to climate change is an important part of preparing for it. In other words, adaptation belongs in the conversation alongside mitigation,” Harris said.
The paper, “Extreme Temperatures, Physical Activity, and Adaptation,” was published April 2, 2026, in the Journal of Public Economics. It is available at https://doi.org/10.1016/j.jpubeco.2026.105638.