Energy demand shifts as cooling rises in the south and heating declines in the north, with long-term projections suggesting global cooling demand may surpass heating demand.

Cooler regions are not exempt from heat challenges; responses must address infrastructure, energy access, and resilience for hotter conditions by mid-century.

The least responsible, often the most disadvantaged, will bear the brunt of more hot days, highlighting the need for low-carbon infrastructure and durable cooling to boost resilience.

Policy and infrastructure implications go beyond environment to social resilience, requiring climate policy realignment and investments in cooling and heat-adaptive urban design.

Findings, published in Nature Sustainability (2026), are based on a global gridded dataset projecting heating and cooling degree days under multiple climate scenarios.

Extreme heat will threaten countries unaccustomed to high temperatures, including Canada, Russia, and Finland, where buildings and infrastructure aren’t built for heat and cooling capacity remains limited, even as some cool regions may see heating demand decline.

Temperate regions such as the United Kingdom, Scandinavia, Austria, and Canada could see the number of hot days double or triple, exposing designs and infrastructure that are not prepared for new heat regimes.

Even moderate increases in hot days could have severe impacts in regions like Canada, Russia, and Finland, underscoring the need for adaptation beyond tropics.

A key finding is that the largest shift toward extreme heat is expected early in the warming trajectory, around the 1.5°C phase, signaling urgency for early adaptation and mitigation.

A University of Oxford projection shows hundreds of millions could face extreme heat by mid-century, with nearly 3.8 billion people exposed under a 2°C warming scenario.

Under a 2°C scenario, extreme heat exposure could rise from about 1.54 billion in 2010 to roughly 3.79 billion by 2050, affecting about 41% of the world population.

The study finds warming scenarios suggest extreme heat exposure could nearly double by 2050, underscoring health and adaptation risks.