Key message 4 – Decisions about the city’s physical characteristics and infrastructure today will lock-in long-term consequences for the future.

The typical lifespan of urban infrastructure and building stock is estimated at approximately 125 and 75 years respectively (IEA 2020). As cities grow rapidly, choices on transport, infrastructure, buildings, and industry will determine the technology, institutions and behaviours they lock in—with direct implications on future emissions. For example, in non-OECD countries, infrastructure related to power, industry, transport and buildings which was built or under construction in 2011 has locked in—or permanently committed to—360 gigatonnes of carbon emissions until 2035 (IEA 2013).

While growth and adaptation remain the priority for rapidly urbanising developing economies, they also have an important choice to make on whether to adopt high or low resource-intensive development paths. The former may appear cheaper in the short-run and require less careful planning. But recent evidence shows that, compared to continued fossil fuel use, a rapid green energy transition will result in trillions of net savings in the long-term (Way et al. 2022). Furthermore, if less efficient technologies are chosen now, longer-term investments in built environment, energy and connectivity will more than triple in order to reverse the carbon output (IEA 2013).

The chosen energy mix, which is the biggest contributor to global GHG emissions, is a major factor that will impact what complementary ‘green’ technologies can be employed across the economy (Stern and Valero 2021). It will affect whether electric vehicles become a viable option in a particular city, protecting against future volatility in fossil fuel prices and reducing local air pollution. It will also determine the viability of green industry and trade that the city can build comparative advantages in (see companion piece Delbridge et al. 2022). Another example is immobile physical capital—commercial and residential buildings. As cities are rapidly growing, the built environment needs to be constructed. Sustainable building construction employed now can reduce current and future emissions, while also helping cities to adapt to the effects of climate change.

While currently African cities are relatively low carbon emitters in absolute terms, their economies are relatively more carbon intensive (see Figure 4 below). In fact, carbon intensity in Africa–measured in kg of carbon dioxide per international US$ of GDP of output—is higher than in Europe. Asian economies are more carbon intensive still. Assessing what bottlenecks and incentive structures are inhibiting a green transition and acting for their removal will help in avoiding lock-in to this more costly development pathway in the long term. In particular, identifying appropriate financing mechanisms – that are accessible and easy to navigate, focus on local priorities, and account for climate justice considerations—is vital. This will help developing cities to weather possible higher upfront investment costs.

Figure 4: Carbon intensity of economies.

Source: Author’s own calculations based on Global Carbon Project and Maddison Project Database 2020 (Bolt and van Zanden 2020).

Notes: Carbon dioxide (CO2) intensity of economies measured in kilograms of CO2 per international US$ of GDP, 2011 prices. For ease of comparison, continental data on CO2 intensity is: Europe – 0.23; Africa – 0.24; Asia – 0.38; North America – 0.29; South America – 0.18; Oceania – 0.33. Click here and here to access the interactive versions of these maps.