The Invisible Threat

‘Extreme heat is known as the “silent killer” because it is both more deadly and less visible than other climate risks like flooding’ (Climate and Development Knowledge Network, 2021)

Although Freetown has always experienced high temperatures, in recent years, there has been a rise in frequent and prolonged dry spells due to climate change. This heat leads to serious health risks like stress and heatstrokes.

In urban areas like Freetown, heat also compounds the negative health impacts of air pollution, a known cause of respiratory illnesses. Meanwhile, the rainy seasons, which once brought relief, are suffused by torrential rains that cause both pluvial flooding and coastal flooding due to the rise in sea levels. Higher temperatures during the rainy season also create a conducive environment for biting insects, like mosquitoes, to breed.

With the city’s growing population increasing the demand for housing and land, many are led to live in informal settlements, which are densely populated and often form in high-risk areas, like steep hillsides, coastal areas, and swamps. These residents experience even higher temperatures and heat indices than other areas.

Realizing the urgent need to systematically curb how climate change (heat islands) is affecting its people, the Freetown City Council has set the goal of reducing urban heat by 60% by 2030. A crucial element to reaching this goal is thermal mapping, which highlights “hotspots”, sources of heat, by detecting infrared wavelengths of structures. With this data, the city and communities will be able to plan towards actualizing the goal of building safe, climate-resilient communities to mitigate and adapt to extreme climate events.

Combatting Urban Heating with Geospatial Data

To achieve this, we will be collaborating with the Freetown City Council (FCC), Centre of Dialogue on Human Settlement and Poverty Alleviation (CODOHSAPA), Federation of Urban and Rural Poor (FEDURP), OpenStreetMap Sierra Leone (OSM-SL), among others, to ideate tools, methodologies, and create data and lasting skills infrastructure:

• First, we’ll be training and supporting residents to gather thermal drone imagery to pinpoint heat exposure hotspots and critical infrastructure data, using the Drone Tasking Manager, OpenAerialMap, fAIr, Mapillary, and Field Tasking Manager.
• This will be followed by co-creating digital maps of neighbourhoods in the city that will be cross-referenced with community heat hotspots and heat resilience.
• The data collected will enable our partners and other stakeholders to make informed decisions, such as investing in community-led heat resilience programs that can mitigate the effects of extreme heat exposure in Freetown City.
• We’ll also support informal settlement residents through microgrants to implement climate resilience solutions that align with heat data analysis and their own community experience with urban heat impacts.

What Will Heat Data Enable?

This citizen-led data process fosters a sustainable approach to capturing and sharing inclusive, up-to-date community-level information. It will keep city planners well informed to deploy resources and make decisions such as:

• where to invest in developing green spaces or adapting public buildings to reduce heat islands,
• which communities should be prioritized for roof upgrading or replacement,
• what essential services are vulnerable to extreme heat,
• which settlements have the least access to potable water, and more.

For communities, this map data can help prioritize upgrades to homes and businesses to improve resistance to extreme heat and guide implementation of urban greening and neighbourhood regeneration where it will have the most impact.