As temperatures rise, cities across the globe face the threat of extreme heat. Between 2002 and 2010, Nepal had more than two dozen destructive heatwaves, with the most severe occurring in 2009 and 2010, leading to 25 deaths and affecting 280 individuals. Alarmingly, about 80 percent of Nepal’s population is at risk from natural and climate-induced hazards like heat waves.

Cities suffer more from heat waves for a few reasons. First is the urban heat island effect, where cities get hotter than villages. This happens because cities are cramped with people, buildings and infrastructure that absorb and retain heat. So, urban centres remain hot even at night when things should cool down, creating a hot bubble over the city that is several degrees warmer than outside. In particular, Kathmandu’s built-up area is almost four times what it was in the mid-1980s. Also, everything we do in cities, like running air conditioners, driving vehicles, working in factories and doing industrial activities, creates even more heat.

Additionally, urban centres lack trees or open water bodies to cool things down naturally. This puts city dwellers, especially older people and those with health issues or limited resources, at risk. Addressing these challenges requires innovative urban planning and integrated green infrastructure.

Growing threat

Nepal is witnessing a rise in both the frequency and intensity of heat waves, particularly in cities. The Ministry of Health and Population recently urged the public to take preventive measures against heat waves. The World Meteorological Organization (WMO) reports that the impact of heat waves became more severe in 2023, making life increasingly difficult. A study by the Department of Hydrology and Meteorology (DHM), Government of Nepal, 2017 showed that Nepal’s average maximum temperature has risen by 0.056 degrees Celsius, with most places getting hotter yearly.

Heat is causing major problems, especially for the poor and underprivileged. High temperatures contribute to drought, forest fires and floods, posing serious threats to human health, lives and the nation’s economy. For instance, on April 19, 2023, there were more than 2,800 forest fires in Nepal in a single day. Following the massive forest fire across the country, Kathmandu became one of the world's most polluted cities, according to the Air Quality Index. Also, this year, over 4,500 wildfires have been reported in the country, almost double last year's, mostly because it’s getting hotter.

These heatwaves don’t just hurt people right away. Being out in the heat for a long time can cause serious health problems and chronic conditions, such as cardiovascular and respiratory diseases. Feeling tired, dizzy, thirsty, headaches, leg cramps, muscle pain, vomiting, dizziness and fainting are immediate signs of too much exposure to excessive heat. Heat-related severe illnesses like heat stroke need immediate medical attention, and this puts more pressure on healthcare systems. The economic cost is significant, too, with damage to infrastructure, reduced productivity and increased energy demands for cooling.

Recent findings

A recent study in the Theoretical and Applied Climatology journal examines the spatiotemporal characterisation of heatwaves in Kathmandu. It develops a methodological framework and suggests ways to lessen the heat impacts. Utilising satellite-based data, essential for developing countries like Nepal where adequate measuring stations are lacking, the study shows that higher temperatures are concentrated in valleys with high population densities.

It is high time we took appropriate mitigation measures in urban planning, building infrastructure and at the household and community levels. The study also highlights a notable rise in extreme heatwave conditions, especially from 2012 onwards. A significant urban warming trend, primarily observed in densely populated regions, suggests that the elderly and youth with limited capacities are highly vulnerable to extreme heat.

Mitigation strategies

Cities need to plan better and include more green spaces to deal with the growing risk of heatwaves. We must figure out how much cooler and to what spatial extent parks, ponds and forests serve effectively. By optimising the design, distribution and maintenance of green infrastructure, cities can use nature to cool things down and make cities resilient. Parks and gardens don’t just provide shade; they also cool things by letting water evaporate from plants and water bodies.

Another strategy involves using appropriate construction materials, such as cool roofs and pavements. Vegetation-covered green roofs can also help keep buildings cooler.

Policy implications

Policies encouraging the adoption of green infrastructure, regulations on urban heat management and incentives for buildings using cool roofing materials can make a significant difference. Public awareness campaigns are also crucial. We must teach everyone about why green infrastructure is good and ways to stay safe in the heat, like drinking enough water and not toiling too much outside when it is super hot.

The escalating threat of heatwaves in Nepal’s cities demands immediate and innovative action. Integrating green spaces, water bodies, and other natural elements into urban design is not just an option anymore—we must make cities good places for the next generation to live. The future of city life in a warming world depends on our ability to innovate and adapt. It is high time to make our cities that withstand the challenges of climate change and be great places to live. It’s a job for everyone—governments, city planners and people from all walks of life—to work together to make cities cooler.