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Overview

Climate change is already resulting in rising temperatures and even more so in Freetown as it experiences the urban heat island effect. The urban heat island (UHI) impact shows a higher air and land surface temperature (LST) in urban regions in contrast with the encompassing rural area.

“I am not sure if this is a heat wave but it is rather hot”

Goals

  • Identify Freetown’s heat risk areas
  • Increase the resilience to heat impacts in heat island areas using heat sensitive infrastructure
  • Support the integration of heat risk measures within regulatory frameworks

Vision

Freetown increases its climate resilience to heat impacts, becoming a more livable, cool and sustainable city for its people

LST maps of Freetown city on different dates ((a) 26 December 1988, (b) 9 March 1998, (c) 3 February 2000, (d) 22 February 2010, (e) 12 February 2018) 

Climate change is already resulting in rising temperatures and even more so in Freetown as it experiences the urban heat island effect. The urban heat island (UHI) impact shows a higher air and land surface temperature (LST) in urban regions in contrast with the encompassing rural area. The UHI is generated by high levels of near-surface energy emission, solar radiation absorption of ground objects, and low rates of evapotranspiration.  This is as a result of urbanization, which causes the conversion of natural land surfaces into anthropogenic impervious surfaces; consequently, causing an urban climate that is warming systematically since the last decades. Such heat rises and warming causes numerous biophysical well-being intricacies like heat stress, air contamination, and other well-being-related issues. 


In Freetown, the average temperature is expected to increase from 29 degrees Celsius to 35 by 2030. Locally, the predictions for South-eastern regions where low-density residential areas are found are moderately cooler than Northern-eastern regions where high-density residential areas are found. Urban expansion development will be accompanied by surface temperature increments, especially in Freetown’s western metropolitan area. Predictions demonstrate that land surface temperatures underneath 32˚C will possibly stay common in the northern half, where low and medium density residential is found. Besides, expecting that development patterns observed between 2000 and 2018 will endure, the extension of high-density built-up areas will bring about high surface temperatures (over 35˚C) in eastern regions, such as in high-density residential areas. It is worth noting that the LST expanded for all land cover types. 

Increasing temperatures create a number of challenges for Freetown. Sunlight and high-temperature trigger chemical reactions between primary air pollutants such as nitrogen oxides (emitted by engines) and oxygen, causing a chemical reaction that forms ozone. The hotter the day and the more intense the sun, the more ozone is formed which results in air pollution worsening the already critical situation. Further, 65% of Sierra Leone’s population depends on subsistence farming and extreme heat lower’s crop productivity level, pressuring food systems further. This combined with the effect of a ten year long civil war has led to an increase in rural urban migration and the rise of internally displaced persons in Freetown. The influx of rural migrants to Freetown has led to population increase, the expansion of the city and growth of informal settlements. In informal settlements – the city now has 74 informal settlements – exposure to high temperatures is even more severe as most are living in houses-built form zinc and can’t afford the use of appropriate building materials and cooling systems, such as ACs to prevent them from the ravaging heat effects. Heat also exacerbates vector diseases, such as malaria, the disease which is responsible for the particularly high under 5 and infant mortality rate. Indirectly, extreme heat is also closely linked to plastic and air pollution; during the day, the demand for drinking water increases due to heat exhaustions, people tend to buy and consume lot of plastic branded water as a quicker and cheaper alternative to satisfy their thirst and when the temperature is extremely hot, harmful gas such as methane is released into the thermosphere causing air pollution. Lastly, extreme heat reduces active transport; It’s very difficult for residents to walk, jug or conduct cycling activities during the day which in turn increases health issues.

It is critical that Freetown invests in measures to reduce the UHI effect and LST. For example, different factors, such as effective mitigation procedures and changes in city development policies, can impact surface temperature patterns. By planting trees, creating parks and open spaces, urban planning can   also produce multi-functional components that provide essential cooling in mitigation of the urban heat island effect. In addition, as future infrastructure investment occurs construction materials and design should be climate sensitive and consider heat stress and flood risk.

LST map of Freetown city in 2030. 

LST map of Freetown city in 2030. 

Increasing temperatures create a number of challenges for Freetown. Sunlight and high-temperature trigger chemical reactions between primary air pollutants such as nitrogen oxides (emitted by engines) and oxygen, causing a chemical reaction that forms ozone. The hotter the day and the more intense the sun, the more ozone is formed which results in air pollution worsening the already critical situation. Further, 65% of Sierra Leone’s population depends on subsistence farming and extreme heat lower’s crop productivity level, pressuring food systems further. This combined with the effect of a ten year long civil war has led to an increase in rural urban migration and the rise of internally displaced persons in Freetown. The influx of rural migrants to Freetown has led to population increase, the expansion of the city and growth of informal settlements. In informal settlements – the city now has 74 informal settlements – exposure to high temperatures is even more severe as most are living in houses-built form zinc and can’t afford the use of appropriate building materials and cooling systems, such as ACs to prevent them from the ravaging heat effects. Heat also exacerbates vector diseases, such as malaria, the disease which is responsible for the particularly high under 5 and infant mortality rate. Indirectly, extreme heat is also closely linked to plastic and air pollution; during the day, the demand for drinking water increases due to heat exhaustions, people tend to buy and consume lot of plastic branded water as a quicker and cheaper alternative to satisfy their thirst and when the temperature is extremely hot, harmful gas such as methane is released into the thermosphere causing air pollution. Lastly, extreme heat reduces active transport; It’s very difficult for residents to walk, jug or conduct cycling activities during the day which in turn increases health issues.

It is critical that Freetown invests in measures to reduce the UHI effect and LST. For example, different factors, such as effective mitigation procedures and changes in city development policies, can impact surface temperature patterns. By planting trees, creating parks and open spaces, urban planning can   also produce multi-functional components that provide essential cooling in mitigation of the urban heat island effect. In addition, as future infrastructure investment occurs construction materials and design should be climate sensitive and consider heat stress and flood risk.

Targets 2030/2050

Target

Heat Maps

Early alarm System

Decrease the heat impact

2030

Freetown has mapped the heat risk in the whole territory (100%)

Freetown has set a threshold and developed heat early alarm system

Freetown has increased the shading (green canopy and shading infrastructures) at 50% of the most vulnerable heat areas (hot spot areas)

2050

Freetown has assessed the interdependencies and cascading effects of heat events

 

80% of Freetown’s residents received early warning messages and response to heat wave

Freetown has increased the shading (green canopy and shading infrastructure) at 100% of the most vulnerable heat areas (hot spot areas)

Source

Internal development

Internal development

Internal development

Targets 2030/2050

Targets

Freetown has mapped the heat risk in the whole territory (100%)

Freetown has assessed the interdependencies and cascading effects of heat events

Internal development

Targets

Freetown has set a threshold and developed heat early alarm system

80% of Freetown’s residents received early warning messages and response to heat wave

Internal development

Targets

Freetown has increased the shading (green canopy and shading infrastructures) at 50% of the most vulnerable heat areas (hot spot areas)

Freetown has increased the shading (green canopy and shading infrastructure) at 100% of the most vulnerable heat areas (hot spot areas)

Internal Development

Note:

These targets are preliminary on the basis of the knowledge and data that has been gathered during the process of developing this plan. A heat mapping assessment and perception study is already underway and will support the identification of the effect of extreme heat on communities and fill knowledge gaps where possible. A revision of the above targets is hence envisioned, as well as the development of a detailed Heat Action Plan centering around the above identified goals.