Major capitals such as Paris, Jakarta, Seoul, and Beijing have seen a continuous increase in the number of days with temperatures exceeding 35 degrees Celsius over the past 30 years.
Many capitals around the world will experience even more extreme heat days, according to an analysis by the International Institute for Environment and Development (IIED) published on June 28. This dangerous trend is driven by rising temperatures across Asia amid a worsening climate crisis. The 20 most populous cities in the world, home to over 300 million people, have recorded a 52% increase in the number of days with temperatures above 35 degrees Celsius over the past three decades, CNN reports.
From Buenos Aires, Argentina, to Paris, France, and Cairo, Egypt, the research found that each passing decade sees an increase in greenhouse gas emissions caused by human activity. Major capitals face more and more heatwave days, threatening human health, the economy, and infrastructure.
A boy pours water over his head to cool off in a densely populated area of Jakarta on May 16, 2024. (Photo: Willy Kurniawan/Reuters)
“Climate change is not just a future threat but is happening now and getting worse,” says researcher Tucker Landesman from IIED. “The situation is exacerbated by the urban heat island effect, which occurs when cities replace natural land with roads and buildings that retain heat.”
Asian cities, which account for about half of the world’s most populous capitals, have experienced the greatest temperature increases. This trend has been particularly evident in recent heatwaves across the continent, from Southeast Asia to China and India. Asia is especially vulnerable to climate risks due to its high population density, poverty, and the proportion of people living in low-lying areas prone to flooding, rising sea levels, and numerous other natural disasters.
New Delhi ranks at the top of the hottest cities list, reporting 4,222 days with temperatures above 35 degrees Celsius in the past 30 years, more than any other city analyzed. In late May 2024, an area in New Delhi reached 49.9 degrees Celsius, the highest temperature recorded in the city’s history, putting pressure on India’s power grid and energy supply systems. The heat lingered overnight, making it difficult for residents to rest.
“We have lived in this neighborhood for 40 years, but we have never experienced a summer like this,” shared Kalyani Saha, a 60-year-old resident of Lajpat Nagar, South East Delhi. “We only get water once a day. It’s burning hot. Water must be filled in buckets and left to cool; otherwise, we can’t bathe with it.” A rickshaw driver mentioned that he has fewer customers as people prefer to take air-conditioned taxis instead of outdoor transport.
Jakarta, the capital of Indonesia, recorded the most significant increase in days exceeding 35 degrees Celsius over the past 30 years (from 28 days between 1994 and 2003 to 167 days from 2014 to 2023). Seoul, South Korea, and Beijing, China, have also experienced a high increase in extreme heat days. In 2018, Seoul recorded 21 days above 35 degrees Celsius, more than the total for the previous decade. The number of days with temperatures over 35 degrees Celsius in Beijing has increased by 309% since 1994.
Cities also face prolonged periods of high temperatures due to governments failing to meet climate goals and adequately reduce emissions. In October 2023, Jakarta experienced 30 consecutive days with temperatures over 35 degrees Celsius, more than the period from 1994 to 2003.
Extreme heat can be very dangerous, especially for vulnerable populations who cannot access cool spaces. From June 11 to 19, New Delhi reported 192 heat-related deaths among the homeless, a record for the same period in the past five years, according to reports from the Indian Health Development Center. Children, the elderly, and pregnant women are at higher risk during heatwaves. Additionally, hourly and informal workers may have to stop working or choose between staying home without income or working in unsafe conditions.
Heatwaves also harm the economy, destroying crops, killing livestock, and reducing labor productivity, especially in areas without air conditioning as workers need to take more breaks to rest and hydrate. Extreme heat puts pressure on infrastructure, including highways, power grids, and railways, disrupting supply chains, causing power outages, and leading to disease outbreaks. According to a 2022 study by Dartmouth College, extreme heat has cost the global economy trillions of dollars since the early 1990s, with poorer nations bearing the brunt of the impact.
