Europe measuring its hottest summer ever; heatwaves ravaging India and Pakistan followed by detrimental floods; and global average annual temperatures reaching 1.2 degrees celsius above pre-industrial levels: 2022 was characterized by multiple extreme weather events as a result of global warming (Copernicus, 2023). In the midst of this, urban areas are highly affected by the climate crisis, while simultaneously contributing significantly to global greenhouse gas (GHG) emissions (Tollin et al., 2022). With more than half of the world’s population living in cities, urban centres play a vital role in both mitigating and adapting to climate change (UN DESA, 2018). How are cities contributing to climate change, and how are they affected by it? This text sets out to explore these questions. Moreover, different urban approaches to climate change mitigation and adaptation will be discussed.
Offender and Victim
Characterised by high population densities and high levels of economic activity, cities contribute considerably to GHG emissions. These emissions can largely be attributed to motorised transport systems and the high energy consumption that distinguish urban areas. Importantly, cities are estimated to account for 70 percent of the total global GHG emissions, and to consume 78 percent of the world’s energy (Tollin et al., 2022). Similarly, it has been found that in Asia, the per capita energy consumption is much higher in urban areas than in rural settings (Atta-ur-Rahman et al., 2016). With the global urban land area predicted to have tripled by 2030 compared to 2000, an imminent need for a more sustainable urbanisation is needed (Revi et al., 2014).
At the same time, cities are severely affected by climate change. During the heatwaves in the summer of 2022, for example, cities were 5 to 9 degrees celsius warmer than their rural counterparts; a phenomenon referred to as the “Urban Heat Island (UHI) effect" (UNEP, 2022). Essentially, cities are warmer because heat is absorbed and radiated by the concrete urban infrastructure, and often being trapped due to densely constructed, high buildings (Rutledge et al., 2022). The lack of vegetation and water bodies in many urban areas amplify this UHI effect. Moreover, extra heat is also created in cities as a result of the high density of people and activities. So-called “waste heat”, generated by for example air conditioning, also causes atmospheric temperatures in cities to rise (Wen & Lian, 2009).
Moving on, the impacts of climate change on cities is dependent on their geologic characteristics. For example, it is found that coastal cities are disproportionately vulnerable to climate change (IPCC, 2022). The wide-spread existence of coastal cities means that currently, more than 40 million people across port cities are already exposed to floodings (Nicholls et al., 2007).
Concurrently, climate change is not only exacerbating the threats of coastal floodings. Moreover, the increasing occurrence of short-duration extreme rainfall is aggravating the risk of urban pluvial floods, putting increasing pressures on urban drainage systems (Revi et al., 2014). Since the soil in cities is typically covered with impervious materials such as concrete, the drainage of precipitation is impeded (IPCC, 2022).
Extreme temperatures and floods are only two of the ample risks cities face due to climate change; other examples being landslides, power outages and water and food shortages. Importantly, the consequences of climate change are not felt evenly across cities, with residents in informal settlements running significantly higher risks (IPCC, 2022). Being often constructed on land sites not formally allocated for residential purposes, infrastructure and housing structures in these settlements are often of poor quality and unreliable in the face of extreme weather (Satterthwaite, 2018; Atta-ur-Rahman et al., 2016). Currently, more than 1 billion people already live in these settlements– a number only expected to grow (Welisiejko & Cáceres, 2022). Informal settlements can mostly be found in the Global South, an already high-risk region with respect to climate change, extreme weather events and (unplanned) urbanisation (IPCC, 2022). Finally, marginalised groups such as women, children and minority communities are disproportionately susceptible to the impacts of climate change.
Mitigating and Adapting
Urban areas all around the world have a responsibility in mitigating rising temperatures and simultaneously adapting to these. In terms of mitigation, bringing down GHG emissions is vital. The IPCC (2022) finds that climate mitigating and adapting measures on a city-level are already widely adopted. Moreover, they state that multi-level governance and top-down approaches are crucial, with community-based action also being important. Measures can range from making cities more energy-efficient and disincentivizing using cars to promoting electric mobility and implementing so-called nature-based solutions. Analysing different studies on climate change mitigation in cities, Sethi et al. (2020) observe that the most effective GHG abatement measures are focused on net-zero emission buildings, applying waste to energy technologies and using E-mobility in transportation. Importantly, they find that most studies on climate change mitigation strategies originate from Europe and China, showing the need for case studies focused on developing countries.
In the OECD, cities are increasingly becoming more fragmented, with lower population densities as a result– a phenomenon referred to as “urban sprawl” (OECD, 2018). Since distances between residential areas and daily trip destinations increase as a consequence of urban sprawl, car usage increases. In the fight against climate change, local governments of sprawling cities are being challenged to curb fragmentation through for example reforming land-use regulations, while simultaneously having to make their cities less car-dependent and green their transport systems (OECD, 2018). Problematically, the alternative to sprawl, -building into the height-, reinforces urban heat islands.
With respect to greening transport systems, multiple strategies are being employed all around the world. These strategies range from investing in intelligent transport systems (traffic lights) that reduce cycling- and public transport travel time in Copenhagen to developing car-free neighbourhoods with the option of car sharing in cities like Utrecht. Another example of greening transport systems is the decarbonisation of public transport (UITP, 2022). Putting greening transportation in a broader context, the above-mentioned examples show that climate change mitigation and adaptation in cities involves the redesigning and improvement of existing urban structures and infrastructure (IPCC, 2022). This, in turn, poses funding challenges for local and regional governments, particularly in developing countries (Revi et al., 2014).
An increasingly applied tool for “sustainable urban planning” is the concept of urban nature-based solutions. The IUCN (2016) defines nature-based solutions as “actions to protect, sustainably manage, and restore natural or modified ecosystems, that address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits.”. According to WWF (2021), nature-based solutions can enhance inclusive, sustainable development in cities located in both the developed and developing world. Examples of nature-based solutions include green roofs, city parks and lakes, urban agriculture and forest and river recovery within cities. These can, among others, moderate the urban heat effect and provide natural drainage systems. Moreover, nature-based solutions have the potential to address multiple societal challenges as depicted in figure 1 (IUCN, 2020). Importantly, all stakeholders, especially marginalised groups, should be involved in and empowered by the design and implementation of nature-based solutions (WFF, 2021).
Figure 1: Societal challenges addressed by nature-based solutions as expressed by the International Union for the Conservation of Nature (IUCN).
Source: IUCN (2016). Defining Nature-based Solutions. https://portals.iucn.org/library/sites/library/files/resrecfiles/WCC_2016_RES_069_EN.pdf
This latter point relates to an important, challenging aspect of building resilience in urban areas: inclusivity. Unfortunately, the IPCC (2022) finds that the adaptation gap (the difference between potential adaptation and actual adaptation) is largest among the urban poor. This, in combination with the fact that it is this group that is the most vulnerable, shows the imminent need to include them in mitigating and adapting strategies. Examples of how the adaptive ability of the most vulnerable groups can be strengthened include involving them in the policy-making process, integrating community-based initiatives in urban planning and partnering with organisations that already help these groups (the World Bank, 2011). Upgrading informal settlements, by for instance providing basic infrastructure and (emergency) services, is important for improving resilience in these communities (Satterthwaite et al., 2018).
In the summer of 2022, heat alerts were issued in almost 90 cities worldwide (UNEP, 2022). Months after the floods in Pakistan, the most urbanised region in South-East Asia, food insecurity and damaged sanitation and other vital infrastructure are plaguing the lives of millions of poor Pakistanis (UN-Habitat, 2022; Unicef, 2023): the consequences of global warming can be felt all around the world, in urban areas no less. In order to reach our climate goals and at the same time build resilience for climate change, cities are at the centre of the action. Noteworthy, the challenges and pathways to mitigation and adaptation that have been touched upon in this article are only the tip of the iceberg– the issues and tasks facing national and urban governments, communities and organisations are manifold and diverse. Notwithstanding the dauntingness of this, local actions and resourcefulness, in addition to involving and cooperating with all stakeholders, are viable and vital steps towards more sustainable and resilient cities. Mitigation and adaptation can start in every city.
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Luka de Laat
Luka is a Dutch student currently in her last semester of the BSc "Economy and Society" at Lund University in Sweden. Passionate about environmental sustainability and thinking innovatively on how to promote sustainable societies and enable ecosystems to thrive.