Figure 5.7: Benefits and limitations of nature-based solutions

Figure 5.7: Benefits and limitations of nature-based solutions

Both urban sprawl and densification (due to the urban heat island effect) pose challenges to public health, natural systems and ecosystem ser vices.171 Rapid urbanization has placed additional demands on urban ecosystem ser vices, thus driving a scarcity of material and biological resources. At the same time, ecosystems are functioning at reduced capacity due to pollution and extraction.172 The pressures of urbanization and increasing population often render urban green and blue infrastructure vulnerable.173 Urban inequalities manifest in differentiated access to ecosystem ser vices, such as less access to green spaces and a reduced urban tree canopy for lower-income urban dwellers.174 These inequalities can have deadly ramifications as climate change impacts urban health.

Urban planning policies across the globe continue to focus on built infrastructure and technological improvements with limited consideration of ecosystems and biodiversity.175 For example, the large-scale conversion of biodiverse areas to farmland or housing impacts negatively on ecosystem ser vices.176 Moreover, urban planning rarely integrates biodiversity and ecosystem ser vices into ser vice and design, aside from demonstration projects.177 Even when focusing on these challenges, urban planning tends to focus on symptomatic short-term and incremental treatments to problems that require transformative planning and long-term solutions.178 Integrating NBSs in policy and planning further suffers from a lack of clarity in the underlying science and the ver y complexity inherent in the dynamics of urban socialecological systems.179 NBSs may arise through collective motivation in the peripheries of cities that lack access to critical infrastructures for water, sanitation, mobility and energy.180 However, NBSs are often perceived as inferior to centralized physical infrastructure (such as electricity networks or large water works) and are usually overlooked when these regions receive connectivity through more extensive city-based networked infrastructures.181

Rural and urban dichotomies persist, despite being challenged on the ground by substantial differences between jurisdictional and administrative boundaries, resource flows and built-up spaces.182 Some fields of study, such as landscape ecology, have moved beyond these dichotomies to recognize gradients of rurality and urbanity—in other words visualizing landscapes where the rural melds into the urban, forming rural-urban continuums.183 Such approaches examine periurban regions’ social and ecological dynamics, especially in developing contexts where centralized infrastructure for critical ecosystem resources such as water and energy provision may often be fragmented, missing or deleterious. However, these approaches are still rare.