Global Warming: How Heat Affects Physical Activity

Scientific alarms are mounting around a discreet yet heavy consequence: a global decline in physical activity driven by climate warming.

Global warming, an escalating constraint on physical activity

According to a study published in the journal The Lancet Global Health(1), in increasingly many regions around the world, climate warming is concretely reducing the opportunities to engage in physical activity, especially outdoors. This phenomenon, still not fully integrated into public health policy, could amplify an already major global crisis of physical inactivity. The rise in temperatures acts as a direct brake on sports and exercise. When heat becomes excessive, the human body struggles to regulate its internal temperature, increasing the risks of dehydration, fatigue, and heat stroke. Physical activity thus becomes not only difficult but also potentially dangerous.

The researchers behind this study are explicit: “Climate change limits the safe opportunities for physical activity worldwide“. This constraint is even more pronounced in tropical and subtropical regions, where heat and humidity routinely reach critical thresholds. High humidity makes things worse: when the air is saturated with water vapor, sweating—the body’s main cooling mechanism—becomes less effective. Thus, even moderate temperatures can become problematic if paired with high humidity, further narrowing the windows for physical activity.

A reduced physical activity in cities under the combined sway of temperature and humidity

This reality particularly affects urban populations, who have fewer alternatives to adapt. Parks are scarce, sports infrastructure sometimes insufficient, and prolonged heat exposure becomes a daily obstacle. Urban heat islands mean city temperatures are often several degrees higher than those in rural areas. Added to this are air pollution and building density, which limit spaces suitable for practicing sports. Consequently, the time window for physical activity narrows. Currently, some regions could lose several hours per day when exercise is considered safe. This means that activities must be moved to the cooler hours, often early in the morning or late in the evening, which is not accessible to everyone.

By reducing opportunities for exercise, the climate acts indirectly as an additional risk factor. Experts speak of a “silent crisis” in expansion. Climate change, traditionally analyzed from an environmental angle, becomes a major determinant of public health.

Adapting physical activity in the face of rising temperatures and humidity

In response to this new reality, adaptation strategies are beginning to emerge. They involve urban planning, public policy, and individual behaviors, all aimed at maintaining a sufficient level of physical activity despite increasingly constraining weather. Some cities are investing in adapted infrastructure, such as shaded spaces, covered sports facilities, or well-ventilated routes. Others are betting on urban greening to reduce local temperatures and improve thermal comfort.

However, these solutions remain unevenly distributed across the globe. The countries most exposed to climate warming are often those with the fewest resources to adapt. This inequality reinforces health disparities, creating a vicious circle that is hard to break. Climate change no longer merely alters landscapes: it profoundly redefines the very conditions of our way of life.