By Sanjaya Bhatia, Head of Office Incheon, UN Office for Disaster Risk Reduction (UNDRR), Republic of Korea

The effects of extreme heat are most acutely felt in urban centres. On average, cities are up to 7°C warmer than the surrounding countryside during the daytime (Gregory, 2021). With this challenge in focus, the UNDRR is promoting an Extreme Urban Heat Risk Management Resource Package under the Making Cities Resilient 2030 initiative. https://www.undrr.org/publication/urban-heat-risk-management-resource-package

The Extreme Heat Challenge

A key barrier to urban cooling is the lack of awareness. There is limited information on best practices, coupled with a lack of data regarding how extreme heat is impacting communities. These gaps make it difficult for city officials to design and implement cooling action plans.

Another key challenge is financial hurdles. Urban heat reduction strategies, such as cool roofs, vertical greenery, and ventilation corridors, offer long-term benefits compared to immediate cooling responses like air conditioning. Decision-makers are often deterred by the high fixed start-up costs associated with these solutions, leading them to favour traditional cooling methods.

Cities face limited institutional capacities. Implementation is hindered by a lack of resources, expertise, and data. For instance, gaps in data regarding citywide heat levels and shade coverage can obstruct the success of many cooling programmes.

The variety of cooling strategies available can also make decision-making more complex as cities attempt to determine which strategies are most suitable for their specific needs, leading to indecision.

Successful implementation of cooling strategies requires collaboration across various sectors, which can be complicated. For example, increasing urban tree cover involves coordination between the city’s transportation, parks and recreation, planning, and zoning departments.

Finally, the lack of community involvement is a barrier. Without active community engagement, the risk management efforts may not address the needs of the people most affected by extreme heat.

Key Recommendations

Conduct a city baseline assessment: A heat assessment of risk and vulnerability is a first step in effective planning for extreme heat. This means identifying populations and assets most at risk and taking stock of existing green, blue, and grey infrastructure.

Set clear heat-planning goals: It is important to design targets that respond to the needs identified in the baseline assessment. For example, when implementing nature-based solutions, cities could set targets for the total area of green space per resident or for residents’ proximity to that space.

Prioritise equitable access: Low-income communities tend to be more exposed to the dangers of extreme heat and they need to be actively engaged in planning to ensure that the initiatives suit their actual needs.

Build awareness on heat risk reduction: Capacity development programmes to promote understanding of heat risks can help in the better implementation of long-term solutions.

Establish a heat alert system: Using a tiered alert system to inform the public of periods of extreme heat can mitigate the risks.

Engage all stakeholders:  Key departments to engage with include those for city planning, budgeting, buildings, environment, parks, land use, public works, utilities, and roadways. Successful implementation requires cross-sectoral agency participation.

Adopt a variety of heat resilience strategies: Cities can reduce urban heat by using reflective surfaces and materials, adding shading structures, increasing street tree coverage, preserving and establishing green and blue spaces, and increasing ventilation through cooling urban geometry.

Sources:

1. “UN Secretary-General’s Call to Action on Extreme Heat.” World Meteorological Organization, June 25, 2024. https://wmo.int/un-secretary-generals-call-action-extreme-heat.
2. World Bank. “Analysis of Heat Waves and Urban Heat Island Effects in Central European Cities and Implications for Urban Planning,” April 2024. https://openknowledge.worldbank.org/entities/publication/4592911b-f73d-5ac5-b787-a4eab3f7e7b1.
3. UN Habitat. “World Cities Report 2022,” 2022. https://unhabitat.org/wcr/.
4. Paddison, Laura. “The Planet Endures Its Hottest Summer on Record — for the Second Straight Year.” CNN, September 6, 2024. https://www.cnn.com/2024/09/05/climate/hottest-summer-record-copernicus/index.html.
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6. Zhong, Raymond, and Keith Collins. “See How 2023 Shattered Records to Become the Hottest Year.” The New York Times, January 9, 2024, sec. Climate. https://www.nytimes.com/2024/01/09/climate/2023-warmest-year-record.html.
7. Gregory, Jeremy, and Hessam Azarijafari. “Urban Heat Islands | MIT Climate Portal.” Climate Portal MIT, April 16, 2021. https://climate.mit.edu/explainers/urban-heat-islands
8. Campbell, Iain, Sneha Sachar, Julia Meisel, and Rushad Nanavatty. “Beating the Heat: A Sustainable Cooling Handbook for Cities.” Cool Coalition (blog), November 5, 2021. https://coolcoalition.org/beating-the-heat-a-sustainable-cooling-handbook-for-cities/.
9. Hoverter, Sarah. “Adaptation Tool Kit: Urban Heat – Georgetown Climate Center.” georgetownclimatecenter.org, August 17, 2012. https://www.georgetownclimate.org/reports/adaptation-tool-kit-urban-heat.html
10. Campbell, Iain, Sneha Sachar, Julia Meisel, and Rushad Nanavatty. “Beating the Heat: A Sustainable Cooling Handbook for Cities.” Cool Coalition (blog), November 5, 2021. https://coolcoalition.org/beating-the-heat-a-sustainable-cooling-handbook-for-cities/.
11. C40 Cities Climate Leadership Group. “Neighbourhood Level Cooling: Experiences from C40’s Cool Cities Network.” C40, April 2021. https://www.c40knowledgehub.org/s/article/Neighbourhood-Level-Cooling-Experiences-from-C40s-Cool-Cities-Network?language=en_US.
12. Singh, Roop, Julie Arrighi, Eddie Jjemba, Kate Strachan, Meghan Spires, and Aynur Kadihasanoglu. “Heat Wave Guide for Cities | IFRC.” IFRC, November 20, 2020. https://www.ifrc.org/document/heat-wave-guide-cities.

Disclaimer: The views expressed in this piece are those of the author/s and do not necessarily reflect the views or policies of AIDMI.