Urban areas experiment with cooling technologies to combat climate change

− Cities are seeing rapid population growth in many emerging markets

− Data systems and artificial intelligence can identify and address urban heat islands

− Expansion of green spaces offers recreation and shade to city dwellers

− Sustainable building materials provide protection against extreme heat

With temperatures in cities set to rise in the coming decades, many public and private players in emerging markets are looking to tackle the challenge of extreme heat through technology, sustainable building techniques and the expansion of urban green spaces.

Cities cover just 3% of the Earth’s surface but currently house over half of the world’s population – a figure set to reach 70% by 2050. Urban population growth is predicted to be highest in emerging markets, with 90% of the shift to cities occurring in Asia and Africa, especially South Asia and sub-Saharan Africa.

Urbanisation tends to accelerate economic growth and opportunity in emerging markets, with cities generating roughly 80% of global GDP. However, it also increases exposure to extreme heat.

Buildings and roads, especially when made from materials such as asphalt, absorb the sun’s heat, making urban areas significantly hotter – a phenomenon known as urban heat islands (UHIs).

A 2021 study published in Nature Climate Change found that under high-emissions models, urban areas could warm by more than 4°C by 2100.

Roughly 356,000 people around the world died due to extreme heat in 2019, according to a study last year, and the problem is set to grow unless appropriate measures are taken.

Mapping urban heat

As OBG reported in June 2020, the Covid-19 pandemic helped spur the growth of smart cities, with national and municipal governments tapping into data-collection infrastructure to track and limit the spread of the virus. Similar technologies are now being harnessed to map and mitigate climate change within urban spaces.

Microsoft India, in partnership with the Sustainable Environment and Ecological Development Society, launched the second phase of a heat wave-tracking artificial intelligence model in July 2021. Previously deployed to track cyclone and flood risk in coastal areas, the technology uses satellite imagery and building assessments to measure heat wave risk for urban areas and communicate effective interventions to vulnerable populations.

Tracking emissions in cities can help address UHIs. Cities produce 70% of global greenhouse gas emissions, due partly to motorised transport systems and construction, both of which consume large amounts of fossil fuels.

Governments are increasingly working to spread awareness of the dangers posed by warming cities and mitigate risk.

Founded in 2016, the Global Covenant of Mayors collaborates with city or regional networks, national governments and other partners to combat urban climate change. Its network of more than 12,000 cities around the world focuses on reducing urban greenhouse gas emissions, a key factor behind UHIs.

Economic consequences

Intense urban heat will have significant economic consequences. A 2020 study reported that per capita GDP in South Africa could decline by up to 20% by 2100, as heat puts extra stress on physical labourers working in the fields of construction, mining and agriculture.

To help protect workers, Kuwait, Qatar, Oman, Saudi Arabia and the UAE have all implemented summer work bans, limiting outdoor work when temperatures can reach life-threatening highs.

Traditional urban-development techniques can also help lower temperatures, especially in the MENA region, where urban centres are designed to mitigate heat.

The historic Seffarine district in Fez, Morocco is as much as 8°C cooler than the rest of the city, despite being the most densely populated area. The difference in temperature is largely thanks to narrow, winding streets in almost permanent shade, plus the use of porous building materials, such as clay brick and concrete stones.

Construction materials play a significant role in generating emissions, as well as absorbing the heat that causes UHIs. With more than half of the world’s building stock expected to be constructed over the next 30 years – much of it in emerging markets – countries can opt for renewable building materials that reflect heat and cut energy usage.

In South Africa, for example, low-carbon buildings that meet Green Star standards save an average of 30-40% in both energy consumption and emissions.

Greening efforts

Many tenets of sustainable urban planning also provide relief for UHIs. Green areas help preserve moisture, which cools down surrounding areas. Public transport systems, meanwhile, reduce reliance on cars while limiting heat-absorbing road networks.

Sustainable urban development is projected to generate $1.5trn in annual business value worldwide by 2030.

Latin America, the world’s second-most-urbanised region, offers several key case studies for sustainable urban development.

Spearheaded by the government of Colombia and the World Economic Forum, the BiodiverCities by 2030 initiative seeks to encourage the development of cities alongside the growth of nature.

The informal community of Isidro Fabela in Mexico City offers another helpful example. Reliance on public transport and the use of natural gas for energy and recycled materials for home building have helped to cut down household greenhouse gas emissions to roughly half of the average impact in Mexico’s capital.

Mexico City is also working on expanding its green spaces by planting over 33m trees and shrubs since 2019 as part of its Green Challenge plan.

With a population of around 2m, Curitiba, Brazil is considered one of the world’s greenest cities. It is home to the first bus rapid transit system, which opened in the 1970s, as well as extensive green spaces, with residents having planted more than 1.5m trees along its roadways.

Meanwhile, in Bangkok, Thailand, in November 2022 its city hall announced it would build 100 or more “pocket parks” over the next three years, improving access to green spaces and increasing plant coverage.