Key message 1 – Cities in developing countries are both the most vulnerable to climate change and the most viable solution to managing its impacts.
Climate change is a grave threat to developing countries and a major obstacle to continued poverty alleviation. Firstly, developing countries are at a geographic disadvantage—they are already warmer on average than developed countries, and they also suffer from higher rainfall variability, leading to greater weather extremes (Mirza 2003). Secondly, they are often heavily dependent on agriculture—the most climate-sensitive of all economic sectors (Thornton et al. 2014). Thirdly, their lower incomes and higher climate vulnerabilities make adaptation particularly difficult. The poorest developing countries are being hit earliest and hardest by climate change, even though they have historically contributed little to causing the problem (Friedlingstein et al. 2022).
At the same time, many developing countries are also urbanising rapidly. Cities currently hold 55% of the world’s population (IPCC 2021) and welcome 67 million new residents every year. The urban share is projected to increase to 68% by 2050 (UN DESA 2019). Crucially, 90% of the urban increases in population are expected to occur in developing countries’ cities (IPCC 2021). This is due to both high birth rates and migration, and increasingly compounded by climate-induced migration—both domestic and across borders. The interaction between climate vulnerability, regional income, and urban growth is shown in Figure 1. Here, African cities have higher urbanisation rates (represented by bigger bubbles), lower GDP per capita, and greater vulnerability to the negative impacts of climate change.
Figure 1: Climate vulnerability against GDP per capita with urbanisation rate.
Despite this vulnerability, cities are also the most viable solution to managing the consequences of a changing climate. Recent models by the IPCC show that sustainability and urbanisation are intrinsically linked (Riahi et al. 2017). They define five pathways for development called the Shared Socioeconomic Pathways (SSPs), based on how policymakers respond to challenges of climate change. Figure 2 shows the link between sustainability and urbanisation under two of these projections. Under SSP1—the result of stronger commitments towards adaptation and mitigation—urbanisation is much higher than under the less optimal pathway—SSP3. This is both due to emission efficiencies that compact, environmentally friendly urban areas provide, but also the opportunities they offer for adaptation (Riahi et al. 2017).
Figure 2: Urbanisation under different Shared Socioeconomic Pathways (SSPs).
These adaptation opportunities stem from cities’ greater efficiency in providing resilience-promoting infrastructure and services. They can also be more easily safe-guarded from extreme weather events and natural disasters (see Collier et al. 2018; Dookie and Gannon 2022). Importantly, cities are engines of productivity and rising incomes, which is one of the most important factors in overcoming the shocks and stressors associated with climate change (Oliveira-Cunha 2022).
In terms of mitigation, cities are the centre of economic activity and, therefore, can be hubs of absolute GHG emissions and air pollution.1 However, emission-generating activities tend to be more efficient in urban areas, despite higher incomes and consumption than in rural counterparts. In the majority of regions in the world, urban per capita carbon dioxide emissions are lower than national per capita emissions (IPCC 2022).2 For example, in Africa and the Middle East, national per capita emissions are estimated to be respectively 0.2 and 0.4 tonnes higher than urban. Cities can therefore lower overall emissions through resource efficiency, as well as through the deployment of cleaner technologies or practices at scale. Curbing GHG emissions has local and global benefits. At the local level, it helps in reducing the concentration of air pollutants and improving population health (Carozzi and Roth 2020).
1 Cities’ emissions vary depending on land use, energy consumption and a variety of socioeconomic and geographical factors WEF (2022) “Delivering Climate Resilient Cities Using A Systems Approach.” Insight Report.
2 Except Asia.