The world’s largest capital cities are witnessing an alarming surge in extremely hot days, a trend driven primarily by soaring temperatures across Asia as the climate crisis intensifies. According to a recent study by the International Institute for Environment and Development (IIED), the 20 most populous cities globally have experienced a staggering 52% increase in the number of days exceeding 35 degrees Celsius (95 degrees Fahrenheit) over the past 30 years. This surge in extreme heat days poses significant threats to human health, economies, and infrastructure.
From Buenos Aires in Argentina to Paris in France, and Cairo in Egypt, the study highlights that major capital cities worldwide are recording more extremely hot days with each passing decade. This trend is closely linked to the rise in human-caused greenhouse gas emissions. IIED senior researcher Tucker Landesman emphasized the urgency of the situation, stating, “Climate change is not just a future threat – it’s already happening and getting worse.”
The analysis reveals that the dangerous increase in temperatures is most pronounced in Asian capitals, which are home to some of the world’s largest populations. Cities like Delhi, Beijing, and Tokyo are experiencing unprecedented heat levels, exacerbating the urban heat island effect. This phenomenon occurs when cities replace natural landscapes with concrete and asphalt, which absorb and retain more heat, leading to higher temperatures.
The urban heat island effect significantly amplifies the impact of climate change on cities. Natural landscapes, such as forests and wetlands, help to cool the air through evapotranspiration. However, as cities expand and replace these natural areas with buildings and roads, they lose this cooling effect. As a result, urban areas become significantly warmer than their rural counterparts, especially during heatwaves.
The increasing frequency of extreme heat days in capital cities is more than just an environmental issue; it has profound implications for public health, the economy, and infrastructure. Prolonged exposure to high temperatures can lead to heat-related illnesses and fatalities, particularly among vulnerable populations such as the elderly, children, and those with preexisting health conditions.
Economically, extreme heat can reduce labor productivity, increase energy consumption due to higher demand for air conditioning, and strain public services. Infrastructure is also at risk, as prolonged high temperatures can damage roads, bridges, and buildings, leading to costly repairs and maintenance.
In cities like Cairo, where temperatures regularly exceed 40 degrees Celsius (104 degrees Fahrenheit), the effects are particularly severe. The heat not only affects daily life but also poses challenges to agricultural production and water resources, exacerbating existing socio-economic issues.
To address the rising threat of extreme heat in capital cities, a combination of mitigation and adaptation strategies is essential. Mitigation efforts should focus on reducing greenhouse gas emissions through the adoption of renewable energy sources, enhancing energy efficiency, and promoting sustainable transportation.
Adaptation strategies, on the other hand, should aim to increase urban resilience to extreme heat. This can include the development of green infrastructure, such as parks and green roofs, which can help to cool the air and provide shade. Implementing heat action plans, which outline measures to protect vulnerable populations during heatwaves, is also crucial.
Additionally, urban planning and design must prioritize the creation of cooler, more livable cities. This can be achieved by incorporating reflective materials in buildings and pavements, increasing tree cover, and improving ventilation in urban areas to enhance airflow and reduce heat accumulation.
