Global population living with extreme heat could double by 2050, warns Oxford University study

London: The global population living with extreme heat could double by 2050 if the world reaches an increasingly likely scenario of 2 degrees Celsius of global warming above pre-industrial levels, a University of Oxford study has warned in the UK.

The 'Global gridded dataset of heating and cooling degree days under climate change scenarios' analysis published in the 'Nature Sustainability' journal last week found that the largest affected populations of extreme heat will be in India, Nigeria, Indonesia, Bangladesh, Pakistan and the Philippines.

The Central African Republic, Nigeria, South Sudan, Laos, and Brazil are predicted to see the most significant increases in dangerously hot temperatures.

"Our findings should be a wake-up call," said Dr Radhika Khosla, Associate Professor at the Smith School of Enterprise and the Environment and leader of the Oxford Martin Future of Cooling Programme.

"Overshooting 1.5 degrees Celsius of warming will have an unprecedented impact on everything from education and health to migration and farming. Net-zero sustainable development remains the only established path to reversing this trend for ever hotter days.

"It is imperative politicians regain the initiative towards it," said Khosla, who is also Research Director of the Oxford India Centre for Sustainable Development at Somerville College, University of Oxford.

Most of the extreme heating impacts will be felt early on as the world passes the 1.5 degrees Celsius target set by the United Nations' Paris Agreement in 2015, the researchers behind the study highlight.

They find that while 23 per cent of the world's population lived with extreme heat in 2010, this figure is set to grow to 41 per cent over the next decades. Countries with colder climates will see a much larger relative change in uncomfortably hot days, more than doubling in some cases.

"Our study shows most of the changes in cooling and heating demand occur before reaching the 1.5 degrees Celsius threshold, which will require significant adaptation measures to be implemented early on," said Dr Jesus Lizana, Associate Professor in Engineering Science and lead author of the report.

"For example, many homes may need air conditioning to be installed in the next five years, but temperatures will continue to rise long after that if we hit 2.0 of global warming.

"To achieve the global goal of net-zero carbon emissions by 2050, we must decarbonise the building sector while developing more effective and resilient adaptation strategies," Lizana said.

Compared with the 2006-2016 period, when the global mean temperature increase reached 1 degree Celsius over pre-industrial levels, this study finds that warming to 2 degrees Celsius would lead to a doubling in Austria and Canada, 150 per cent in the UK, Sweden, Finland, 200 per cent in Norway, and a 230 per cent increase in Ireland.

Given that the built environment and infrastructure in these countries are predominantly designed for cold conditions, even a moderate increase in temperature is likely to have disproportionately severe impacts compared with regions that have greater resources, adaptive capacity, and embodied capital to manage heat.

The projected increase in extreme heat will also lead to a significant rise in energy demand for cooling systems and corresponding emissions, while demand for heating in countries like Canada and Switzerland will decrease.

The Oxford University study also includes an open-source dataset of global heating and cooling demand, comprising 30 global maps that capture climate intensity in "cooling degree days" and "heating degree days" worldwide. This dataset is designed as a foundation for incorporating accessible climate data into sustainability planning and development policy.