By 2050, 66% of the world’s population will be living in urban areas, increasing the concentration of people exposed to climate change extremities. To mitigate the risks associated with extreme weather events, particularly flooding, climate change adaptation strategies need to be incorporated into the designing and planning phases of all types of infrastructure.
Current global spending on infrastructure and capital projects is estimated to reach US$9tn by 2025, up from US$4tn in 2012, however, ‘business-as-usual’ investment in infrastructure will not lead to a stable future according to the World Economic Forum. To meet the numerous challenges of climate change there needs to be an additional investment of US$0.7 trillion made per year.
The most common response to storm and flooding risks has been to increase investment in conventional or ‘grey’ infrastructure such as dams and levees to mitigate risks. However, engineers and decision-makers have come to realize the economic and environment costs of these solutions. Economically, grey infrastructure is often capital intensive in building, operating, maintaining and replacing. In addition, as grey infrastructure is mainly built to address a specific water management problem it can amplify risks downstream, for example canals may amplify floods downstream resulting in harm to life and damage to infrastructure. Environmentally, grey infrastructure often degrades quality and quantity of water supply leading to ecosystem degradation. As such, there has been a turn to more long-term economically and environmentally sustainable ‘green’ climate adaptation solutions that provide equivalent or similar benefits to ‘grey’ infrastructure.
Green climate adaptation solutions and flood management
Green adaptation solutions use natural or semi-natural systems that utilize nature’s ecosystem services in the management of water resources and associated risks. Green adaptation solutions can also be used to support the goals of multiple policy areas. For example, floodplains can reduce flooding risks to cities while simultaneously supporting agricultural production and recreational activities. Regarding depreciation costs, green adaptation solutions, unlike grey infrastructure, can appreciate in value over time with the regeneration of nature and its associated ecosystem services.
Green climate adaptation solutions and urban flood management
To reduce the impacts of floods, cities can use green adaptation solutions to increase the water infiltration and storage capacity of wetlands and soils. Specific green adaptation solutions include reforesting along riverbanks, reconnecting rivers to flood plains, constructing green spaces that hold and slowly release floodwater and construction of permeable pavements that enable surface water to infiltrate the soil below. The equivalent grey infrastructure solutions are dams and groundwater pumping, both of which are environmentally and economically costly. Green adaptation solutions can also help cities purify polluted water through combinations of sediments, soils and vegetation that filter out sediments and contaminants in water naturally. The equivalent grey infrastructure solution is wastewater treatment plants.
Benefits of investing in green climate adaptation solutions
Green climate adaptation solutions can bring about multiple benefits for cities including:
- Less damage to infrastructure: Climate change along with rapid urbanization is leading to more infrastructural assets vulnerable to damage from floods. Specifically, green adaptation solutions can be implemented at the local level to protect various types of infrastructure (e.g. water, energy, telephone systems) from local flooding risks.
- Less environmental degradation: Green adaptation solutions can purify water by removing sediments and contaminants before they enter ground and surface water. Green adaptation solutions can also enhance the environment with reforestation and creation of green spaces.
- Fewer disruptions to the local economy: By implementing green adaptation solutions cities can reduce the risks of flooding to vital parts of the city such as industrial or commercial zones, ensuring economic activities continue uninterrupted during flooding events.
- Protection of human health: Green adaptation solutions can reduce the number of people losing their lives or being injured during flooding events by protecting vulnerable areas of cities from flooding events. In addition, green adaptation solutions can be used to ensure water supplies remain contaminant-free during flooding events and channel water away to avoid risk of water-borne diseases.
- Job creation: Cities can employ people to construct and maintain green adaptation solutions. Climate-ready cities can also become attractive locations for companies researching and developing climate adaptation technologies.
With rapid urbanization leading to increased exposure to climate change flooding events investments in green adaptation solutions is critical in protecting the well-being of the population while restoring the health of ecosystems.