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Johannesburg Initiates Measures to Reduce Impact of Heat Island Effect



Johannesburg is facing a heat island effect

Johannesburg is facing a heat island effect, a phenomenon caused by the absorption and retention of heat by buildings, pavement, and other human-made structures. According to the City of Johannesburg, this heat island effect will likely increase energy consumption and air pollution, posing challenges for vulnerable residents. However, the municipality is actively researching and implementing various strategies to mitigate the impact of the heat island effect. Mzukisi Gwata, the principal specialist in the City’s climate change adaptation unit, highlights that Johannesburg is one of the major cities grappling with increased heat exposure, particularly within poorer communities.

“We are now making conscious efforts to be able to respond to heat threats because they form part of the Environment and Infrastructure Services Department’s (EISD) Climate Action Plan (CAP),” explains Gwata.

The City’s CAP outlines how the municipality is working towards achieving emissions reduction targets and reducing the vulnerability of its citizens to the harsh impacts of climate change.

The heat island effect occurs when metropolitan regions, such as Johannesburg, experience higher temperatures than the surrounding rural areas due to heat absorption and retention by buildings, pavement, and other manufactured structures. This heat retention can cause severe consequences for human health and the environment, including increased energy consumption for cooling buildings, exacerbated air pollution and smog formation, and intensified heat-related illnesses.

Furthermore, the heat island effect can disrupt ecosystems and impact biodiversity. Many plants and animals are sensitive to changing temperatures. Urban areas also lack vegetation, reducing the cooling effect of evaporation and the shade provided by trees and plants.


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“Heat waves have different effects on different people. The heat you have during the day is manageable, but the worst is when your temperature doesn’t drop at night to allow you to sleep. There are people who have underlying conditions and children who are not fully developed and not yet able to regulate their body temperatures,” explains Gwata.

Studies conducted in more densely populated and informal settlements have revealed genuine concerns regarding increased heat as these living spaces do not absorb heat but rather regenerate it. Results indicate that these areas have limited tree coverage, and the existing trees are often old and unable to provide significant relief.

“The increased heat is a result of buildings re-emitting it. On the other hand, if we move more towards the south of the City, there are larger open spaces that accumulate less heat,” Gwata points out.

Gwata notes that people living in informal settlements are more susceptible to the heat island effect due to the lack of windows, air conditioning, and access to tap water in their homes. This lack limits their adaptive capacity to withstand the increased heat and cool themselves down.


The municipality and several stakeholders have engaged in citizen-targeted science campaigns and studies to map out neighbourhoods and communities directly impacted by rising temperatures, including Alexandra, Kliptown, and Braamfontein.

Significantly, the City has already taken measures to mitigate the heat island effect. Johannesburg City Parks and Zoo (JCPZ) has been allocated a budget to plant over 10,000 trees annually. Although it may seem like a small effort, it has a noticeable impact, especially in communities lacking adaptive capacities, according to Gwata.

Moreover, the City has contacted the World Bank, seeking participation and assistance in managing the heat island effect in Johannesburg.

“We have created more awareness about the issue of increasing temperatures, and as a unit, we will continue with policy-making and researching the effects of climate change. This allows us to bring forth issues and concerns discovered through climate change science and make them City initiatives to find solutions,” explains Gwata.

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Addressing the heat island effect is a crucial step towards creating more sustainable and livable urban environments, promoting energy efficiency, and mitigating the impacts of climate change.

Residents can also reduce their contributions to the heat island effect and promote a more sustainable environment. Choosing energy-efficient appliances, reducing the use of air conditioning, and cutting down on using single-use plastics can make a significant difference. Additionally, planting trees and creating green spaces in personal gardens or community areas can help counteract the heat island effect by providing shade and cooling.

The City of Johannesburg acknowledges the importance of individual actions in combination with municipal efforts. Gwata encourages residents to actively participate in sustainable practices and engage with local initiatives to address climate change and its impacts.

The heat island effect poses significant challenges for Johannesburg, impacting energy consumption, air quality, and the well-being of vulnerable communities. However, by working with various stakeholders, the municipality is taking steps to lessen these effects through research, policy-making, and community engagement. Johannesburg aims to create more resilient and sustainable urban environments through tree planting, awareness campaigns, and partnerships with organisations like the World Bank.

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Gauteng Residents Advised to Prepare for Incoming Cold Snap

Picture: UnsplashTania Melnyczuk

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