As a water delivery arrives at a restaurant in Istanbul, Turkey, during a sweltering summer day last year, the scene captures a growing global reality. Numerous temperature records were shattered in 2025, setting the stage for a concerning future. A groundbreaking study now warns that the number of people living with extreme heat will more than double by 2050 if global heating reaches 2°C above pre-industrial levels.
No Region Immune to Rising Temperatures
Scientists expect 41% of the projected global population to face these extremes, with no part of the world immune to the impacts. Published in Nature Sustainability, this research represents the most detailed analysis yet of how different regions will encounter temperature extremes as human-driven global heating progresses from 1°C a decade ago towards 1.5°C this decade, potentially reaching 2°C around mid-century without rapid emissions cuts.
Changing Energy Demands Across Hemispheres
The study reveals how this warming will dramatically alter energy demand patterns for temperature management. Over coming decades, the northern hemisphere's heating requirements will decrease while the southern hemisphere's cooling needs increase substantially. Separate research confirms that by century's end, global energy demand from air conditioning will surpass and far exceed that from heating systems.
Researchers defined extremes by how many days each year temperatures deviate from a temperate baseline of 18°C. Using sophisticated computer models, they mapped where the biggest changes will occur and how many people will be affected.
Staggering Population Impact Projections
If the 2°C threshold is breached, the data indicates the number experiencing extreme heat will surge from 1.54 billion people (23% of world population in 2010) to 3.79 billion (41% of projected population in 2050). The majority affected will reside in:
- India
- Nigeria
- Indonesia
- Bangladesh
- Pakistan
- The Philippines
However, the most significant increase in dangerous temperatures will threaten Central African Republic, Nigeria, South Sudan, Laos and Brazil.
Urgent Need for Early Adaptation Measures
In a surprising finding, computer models revealed the greatest shift will occur early in the warming trajectory – near the 1.5°C phase where the world currently stands. This discovery adds considerable urgency to adapting healthcare systems, economic structures and energy infrastructure.
"This is a really core finding because it tells us that we need to act much earlier in supporting measures for adaptation and mitigation," explained study author Radhika Khosla of Oxford University's Smith School of Enterprise and the Environment. "Overshooting 1.5°C of warming will have an unprecedented impact on everything from education and health to migration and farming."
Northern Nations Face Adaptation Challenges
Khosla emphasised that even relatively wealthy northern nations will struggle significantly. "No part of the world will be able to shy away from extreme heat. There is a lack of preparedness across nations," she stated.
In the UK specifically, she noted that buildings and infrastructure are often old, inefficient and primarily designed to cope with cold conditions. When temperature extremes shift in the opposite direction, this poses substantial challenges to health systems, energy supplies and economic stability. The 2023 heatwave demonstrated this vulnerability when the National Grid requested activation of two coal-fired power plant units to manage unprecedented air conditioning demand.
The research underscores that net zero sustainable development remains the only established path to reversing the trend toward ever hotter days. Scientists urge politicians to regain initiative toward this crucial goal as human activity helped make 2025 the third-hottest year on record.
