Cities in low and middle-income countries are experiencing an increase in urban heat island effect, as a result of unplanned expansion, reduced green spaces, and inadequate infrastructure, according to a new analysis.
This phenomenon exacerbates the impacts of climate change and deepens social inequalities in urban areas, where currently more than half of the world’s population resides. By 2050, it is projected that this figure will rise to 70%.
What are urban heat islands?
Densely populated cities, with materials such as concrete and asphalt, trap more heat than nearby rural areas, increasing temperatures within the urban environment.
A study published in the Urban Sustainability journal analyzed over 5 million urban networks between 2003 and 2018. The research determined that cities are warming at an average rate of 0.021 degrees Celsius per year, with a more pronounced increase in low and middle-income countries.
This phenomenon not only reflects temperature differences, but also profound inequalities in urban development and access to green and resilient infrastructure.
Rapid urbanization and lack of mitigation measures
In regions like South Asia, Sub-Saharan Africa, and the Middle East, urban growth is advancing at an unprecedented rate, replacing vegetation with impermeable surfaces that alter the water cycle and contribute to temperature increases.
Urban expansion rarely includes measures to mitigate heat, impacting the quality of life of residents. Cities like Cairo, Karachi, Dhaka, and Nairobi are especially vulnerable, as informal settlements often lack green areas, shade, and efficient cooling systems.
The study also found that the urban heat island effect intensifies during summers, when urban materials absorb the maximum solar radiation, and during winter nights, when heat retained by structures is re-emitted, while rural areas cool down faster.
Climate inequality in urban areas
In a context of increasingly frequent extreme heat events, urban residents with low incomes face higher risks of heat-related illnesses, energy poverty, and even death.
Overcrowded and poorly ventilated housing worsens heat exposure, while many inhabitants lack air conditioning, reliable electricity, and public spaces with shade.
This phenomenon highlights a clear climate injustice, as populations that contribute the least to global emissions are the ones that suffer the most from the effects of climate change.
Solutions to mitigate urban heat
Experts propose simple and locally adapted interventions to combat heat in cities.
Any vegetative cover helps cool urban areas.
Some effective strategies include:
- Rooftop gardens, which enhance vegetative cover.
- Painting facades and roofs white, to reflect heat and reduce thermal absorption.
- Nature-based solutions, which also promote urban biodiversity and improve quality of life.
Urban planning and international cooperation
Researchers emphasize the importance of including climate adaptation in public policies and developing heat action plans, sustainable infrastructure, and inclusive projects to protect vulnerable communities.
It is necessary to invest in resilient solutions, although this requires political commitment and financing, especially in the Global South.
The study authors urge to strengthen international cooperation and increase financial support through mechanisms such as the Green Climate Fund, so that cities in low and middle-income countries develop infrastructure resistant to extreme heat.
