Population living in extreme heat to more than double by 2050 if 2°C warming occurs

The number of people exposed to extreme heat is projected to more than double by 2050 if global warming reaches 2°C above pre-industrial levels, according to a new scientific study that also warns that “no part of the world” will escape increasing temperature extremes.

The research, published in the journal Nature Sustainability, shows that the share of the global population experiencing extreme heat could rise from about 1.54 billion people (23% in 2010) to about 3.79 billion (41% of the world’s projected population in 2050) if average temperatures climb to 2°C. Scientists said this would have profound consequences for human health, energy systems, labour productivity and economic activity.

The authors defined extreme heat based on the number of days per year temperatures exceed a threshold above a temperate baseline of 18°C. Using climate models, they mapped where significant changes are expected and how many people would be affected under different warming scenarios.

The study also highlighted that the most dramatic shifts begin early in the warming process, near the current 1.5°C level, underscoring the urgency of adaptation and mitigation measures.

“No part of the world will be able to shy away from extreme heat. There is a lack of preparedness across nations,” co-author Radhika Khosla of the Smith School of Enterprise and the Environment at Oxford University said. She emphasised that exceeding 1.5°C would have “unprecedented” impacts on health, education, migration and farming, and urged a renewed global commitment to achieving net-zero emissions.

According to the study, India, Nigeria, Indonesia, Bangladesh, Pakistan and the Philippines are among the countries where the largest numbers of people are expected to face extreme heat by mid-century. Central African Republic, Nigeria, South Sudan, Laos and Brazil are highlighted as regions likely to see some of the most significant increases in dangerous temperatures.

The researchers noted that rising heat will reshape global energy demand. In the northern hemisphere, demand for heating is expected to decline over coming decades, while the cooling burden in the southern hemisphere will increase sharply. Separate studies have suggested that by the end of the century, global demand for air-conditioning could exceed heating demand.

The study’s findings come amid a backdrop of record-breaking temperatures. In 2025, scientists said human activity helped make that year the third-hottest on record.

Khosla said governments need to accelerate both adaptation — including upgrading infrastructure, health systems and energy grids — and mitigation through rapid cuts to fossil fuel emissions from oil, gas and coal.

In wealthier nations that have infrastructure designed for cooler climates, the shift poses challenges too. “Buildings and infrastructure are old, inefficient and primarily designed to cope with the cold, so when temperature extremes move in the opposite direction it poses a challenge to health systems, energy supplies and the economy,” she said, citing a 2023 heatwave in the UK that prompted the National Grid to bring coal-fired power plant units online to handle air-conditioning demand.