Addressing the UHI effect in Kathmandu

This summer, Kathmandu experienced its highest temperature ever recorded. The Department of Meteorology and Hydrology (DHM) reported a scorching temperature of 35.3°C on June 15. The city is urbanizing at an annual rate of four percent, and its built-up area has grown to almost four times its size since the mid-1980s. Consequently, the risks associated with the Urban Heat Island effect are also increasing. Research by Mishra et al. (2019) indicated a 5°C temperature variation between forest land and developed land in the Kathmandu Valley. As rapid population growth and unplanned urbanization continue in the valley, the temperature difference is also expected to increase.

Urban Heat Island, or UHI, is a phenomenon where urban areas experience considerably higher temperatures than their surrounding rural areas. The main causes of UHIs include anthropogenic factors, heat absorption by urban infrastructure, and the albedo effect. The albedo effect is a measure of how reflective a surface is. Darker surfaces absorb more heat and release it back into the atmosphere, while lighter surfaces reflect heat away. Therefore, as cities replace natural landscapes with buildings, roads and pavement, which absorb and retain heat, the overall temperature increases. The impacts of UHIs are far-reaching, including air pollution, higher energy consumption, disruption of urban ecosystems and adverse health outcomes, especially for vulnerable populations such as the marginalized, elderly, and urban poor.  

In a country where urban poverty has increased from 15.46 percent in 2010-11 to 18.34 percent in 2022-23, and where the Kathmandu Metropolitan City’s handling of the urban poor has been condemned by Human Rights Watch, critical questions arise—How will the rights of street vendors, landless individuals, slum dwellers and other vulnerable groups be safeguarded amidst rising temperatures? 

Additionally, with heat-related illnesses expected to increase due to the UHI effect, it is crucial to assess whether the healthcare system in Nepal is prepared to handle the added pressure. Will vulnerable groups, with their limited capacities, have access to essential health services, adequate housing, a decent standard of living and an overall quality of life, or will they continue to be mistreated? Despite global awareness regarding UHIs, the concerned authorities in the Kathmandu Metropolitan City are yet to acknowledge the alarming rise in temperatures this summer.

In contrast to this local inaction, cities around the world are actively addressing the UHI effect with innovative solutions. For example, Indian cities like Ahmedabad, Bhopal, Jodhpur and Surat have introduced cool roofs-roofs covered with reflective materials that bring down temperatures inside and outside buildings. Applying white reflective paint on roofs is a simple yet effective strategy that has seen widespread adoption globally. 

Abu Dhabi has introduced self-shading tower blocks, Medellin has developed extensive green corridors, Paris is creating cool islands, Seville has implemented a policy of shade and Singapore boasts of its renowned Gardens by the Bay. These diverse approaches demonstrate how cities are dealing with the UHI effect based on their unique environments and challenges.

In response to escalating temperatures, cities are also appointing Chief Heat Officers (CHOs) – a term coined by a branch of the American think tank Atlantic Council called the Adrienne Arsht-Rockefeller Foundation Resilience Center (Arsht-Rock). CHOs are responsible for developing and implementing strategies to combat extreme heat, protect vulnerable populations and enhance urban resilience to rising temperatures. Miami paved the way by appointing the world’s first CHO, and other cities, such as Phoenix, Athens, Freetown, and Dhaka North followed suit. Notably, Dhaka North was the first Asian city to appoint a CHO.

While cities worldwide, including those in South Asia, are making commendable strides in addressing UHIs, Kathmandu Metropolitan City’s lackluster approach to this issue is highly concerning. Kathmandu must learn from other cities and implement targeted strategies to mitigate the UHI effect or face intensified challenges in the coming years. The rising temperatures in Kathmandu represent the broader challenges posed by global warming, climate change and increased urbanization. These issues demand urgent attention, action and innovative solutions from policymakers, urban planners and the general public.

While initiatives such as Urban Green Spaces (UGS), tree plantations and community-managed forests are underway, a significant gap remains in addressing and raising public awareness on UHIs. Comprehensive research, robust satellite-based data collection and substantial evidence are essential to guide sustainable urban planning. Given the pace and scale of urbanization, the government of Nepal must step up its efforts in urban governance and take appropriate mitigation and adaptation measures by coordinating with relevant ministries and departments to plan greener, smarter and liveable cities. This involves prioritizing the conservation of natural resources and natural heat sinks, investing in alternative energy solutions, and implementing innovative strategies to enhance urban resilience. It is also crucial that policies and plans be grounded in a deep understanding of the local context, addressing challenges facing vulnerable groups, and ensuring that no one is left behind.

The author holds a Master’s degree in Public Policy