Bangladesh to be among world's 6 hottest countries by 2050: Study

Bangladesh will be among the six countries most severely affected by extreme heat by 2050 due to rising temperatures, according to a new study.

A new international study, led by researchers from the University of Oxford in the United Kingdom published today (26 January) in the journal Nature Sustainability, warns that the global heatwave crisis is deepening, with severe consequences for daily life, economies, and public health systems. 

If current fossil fuel consumption continues, the proportion of the world's population exposed to extreme heat could nearly double over the next 25 years, the study points out. 

Should global warming reach 2 degrees Celsius above pre-industrial levels, 41% of the world's population, around 3.79 billion people, will be living under extreme heat conditions by the middle of this century. In 2010, the figure stood at 23%, or about 1.54 billion people.

Using high-resolution climate and population models, the researchers assessed heatwave risks through the "Cooling Degree Days" (CDD) index. Regions experiencing more than 3,000 CDDs per year were classified as "extreme heat-prone." 

The index measures the amount of cooling required to maintain safe indoor temperatures. Based on this threshold, countries with the largest populations living under extreme heat include India, Nigeria, Indonesia, Bangladesh, Pakistan, and the Philippines.

Lead author Dr Jesus Lizana of the University of Oxford said national average temperatures can mask the real risks in countries like Bangladesh. 

"In reality, most people in the country live in areas where annual cooling demand exceeds 3,000 CDDs. This means prolonged and dangerous exposure to heat, which affects human survival, productivity, and health," he said.

The study notes that Bangladesh is already considered one of the world's most climate-vulnerable countries, and the study adds a new dimension of heat stress to that risk. While attention has long focused on sea-level rise, cyclones, and flooding, extreme heat is emerging as a silent yet equally deadly threat.

Experts note that heatwaves significantly increase the risk of heatstroke, cardiovascular stress, and kidney disease – particularly among the elderly, children, and low-income populations with limited access to cooling.

The Oxford-led study also finds that rising temperatures will drive the fastest growth in cooling demand in low- and middle-income countries in tropical and subtropical regions. In contrast, wealthier countries in the Global North are likely to see reduced demand for heating as winters become milder.

Per capita Cooling Degree Days are projected to rise the most in the Central African Republic, Nigeria, South Sudan, Laos, and Brazil. Conversely, countries such as Canada, Russia, Finland, Sweden, and Norway are expected to require less heating due to warmer winters.

The study further projects that by 2050, the share of the global population living in "very cold" regions will fall from 14% to just 7%. 

Researchers also warn of a potential "cooling trap" in extreme heat-prone countries, where rising demand for air conditioning could increase energy use and, if met with fossil fuels, further accelerate climate change.

Overall, the findings underscore that the window to prevent the worst impacts of extreme heat is rapidly closing. Scientists say keeping global warming close to 1.5 degrees Celsius could significantly reduce the number of people exposed to life-threatening heat.