Report Shows Rising Temperatures in World’s Major Capital Cities

From Dhaka to London, Cairo, Manila, and Paris, these capital cities are among the world’s top 20 most populated cities, home to 300 million people.

With growing greenhouse gas emissions, they are experiencing a surge in high temperatures. Consequently, millions of people are facing escalating levels of heat stress, posing threats to human health, infrastructure, and the economy.

A new study from UK-based International Institute for Environment and Development the International Institute for Environment and Development (IIED) released on 28 June 2024 shows that the 20 most populous capital cities have experienced 52% increases in the number of days with temperatures reaching 35°C in the past thirty years.

The rising temperatures come as no surprise. The global average temperature is breaking records for twelve consecutive months from July 2023 to June 2023, the highest ever measured at 1.64°C above the pre-industrial average, according to data from the Copernicus Climate Change Service. With El Niño, the “warm phase” of a larger phenomenon called the El Niño-Southern Oscillation (ENSO) has only recently ended, boosting the record-breaking temperatures across the planet over the past year.

According to the IIED report, New Delhi has taken the top spot for the hottest capital in the world, recording 4,222 days above 35°C in the last 30 years. In the last ten years alone, 44% of the days in the city reached 35°C, a significant increase compared to the past two decades.

Jakarta has taken the second spot for the most hot days, with a significant rise in the number of days surpassing 35°C over the last three decades. Between 1994-2003, there were only 28 days over 35°C in Jakarta. However, in the subsequent decade (2004-2013), this figure surged to 153 days, and in the most recent decade (2014-2023), it further escalated to 167 days.

Other cities with a steep rise in the number of hot days include Seoul, Buenos Aires, and Beijing.

The report notes that not only is the number of hot days increasing, but also the number of consecutive days of extreme heat. For instance, Jakarta saw 30 straight days of over 35°C in October 2023, exceeding the 10-year period between 1994 and 2003.

Extreme heat kills people, reduces labour productivity, and damages crops and livestock

Over 1,300 pilgrims died in Saudi Arabia during the hajj as the temperature soared above 50°C. In Mexico,  hundreds of howler monkeys died due to the heatwave. Delhi, India, endured 40 days above 40°C between May and June.

The Lancet 2021 report estimates 489,075 heat-related deaths between 1 January 2000 and 31 December 2019. More than half of these excess deaths are in Asia, and nearly a quarter occurred in Africa. Excess deaths in the report refer to how many people died within the period compared to what would have typically occurred.

Exposure to extreme heat can have serious health consequences, including heat stroke, heat stress, and worsening existing health conditions like heart disease, diabetes, and acute kidney injury. Infants and older adults are particularly vulnerable to adverse health effects from heat exposure.

The problem of extreme heat is also acute in poor countries, particularly in crowded areas and slum areas that use cheap building materials such as metal roofs and areas that lack trees or vegetation to help cool the area.  

Extreme heat also stresses infrastructure such as roads, railways, and electric networks and can cause supply and travel disruptions and blackouts.

Adapting to heat

Improving early warning systems, especially in hot areas and cities, can help prevent heat-related fatalities and health impacts. Governments can also mandate heat-related regulations such as heat standards for indoor workers and access to water, rest, and shade when temperatures soar for outdoor workers.

In Spain, the government has taken the following measures to reduce residents’ exposure to extreme heat: changing school hours or reducing them, increasing public transport frequency, subsidising air conditioning in people’s homes, and coordinating a heatwave alert system. On a household level, owners can paint their house white or install awnings or window shutters to keep the sun out. Madrid, the country’s capital, opened air-conditioned public spaces like museums and encouraged people to use them.

In some cities in America, India, and Vietnam, “cooling centres” offer relief and refuge from the heat. These spaces are often libraries or offices that are open to the public.

As temperatures rise, scorching hot summers are becoming increasingly unavoidable. However, with proper planning and strategies, cities can prevent or reduce heat-related deaths and health impacts.