Earlier this year, ADB released A Region at Risk, a major report on the impacts of climate change in Asia and the Pacific. While the study focuses on the impact of warming on socio-economic systems, Asia’s natural ecosystems will also feel the impacts.
The vulnerability of the region’s natural eco-systems is broadly under-appreciated. It is imperative to strengthen the resilience of both natural systems and human societies if the region is to secure a sustainable future.
Over the last decade, a range of nature-based approaches to enhancing resilience have emerged from multiple disciplines, They share a common theme, namely that we can use natural systems and work together with nature to increase the resilience and adaptive capacity of our societies against climate and disaster risks.
These approaches, often called nature-based climate solutions, include ecosystem-based adaptation, ecosystem-based disaster risk reduction, green/blue infrastructure, and ecological engineering.
By protecting and managing natural systems where they are currently under threat, and by restoring them where they have been disturbed or removed, we can preserve their integrity and improve their resilience.
Preserved natural systems provide a range of services in support of human societies. These services are not only necessary for societies to continue to exist – they also contribute directly to their economic development and their overall resilience.
Promoting climate, disaster resilience
We can improve the resilience of societies and vulnerable communities by using the characteristics of natural systems either alone or in combination with conventional (hard) infrastructure.
A good example of this approach is how restoring coastal habitats like mangroves helps to reduce the impact of increased storm surges and sea level rise. Another is the introduction of constructed wetlands in certain areas to improve water quality and drainage, thereby reducing pollution and flood risks.
ADB recently organized an international workshop on the use of nature-based solutions in four contexts—urban development, water and river basin management, coastal protection and disaster risk reduction—to promote climate and disaster resilience in ADB investments. Below are key learning points that emerged from the discussions.
Nature-based solutions offer opportunities to improve the use of open space, particularly in the urban context, and to deliver a wide range of non-market, community-level resilience dividends. This includes low-regret actions that already are cost effective now, as they provide socio-economic benefits under the current climate and regardless of future climate conditions.
Examples of such actions include reforestation and vegetation management to reduce soil erosion and control reservoir sedimentation, or wetland restoration to reduce flood risks downstream and improve water quality.
In addition, investments in ecosystems often have climate change mitigation potential.
Integration with infrastructure
Nature-based approaches are often effective and efficient complements to engineering solutions, particularly when integrated across sectors and scaled on a participatory and consultative basis.
For example, mangroves as a stand-alone solution may not always offer full protection against large magnitude hazards like tsunamis or cyclones. We may often need to integrate mangroves into the overall design of coastal defense infrastructure, such as seawalls and revetments.
Also, they can have lower costs and/or higher benefits compared to hard infrastructure investments. They are also more flexible and better able to dynamically adapt and respond to a changing climate.
However, ecosystem-based approaches have some limitations. They usually require more land or sea space than an engineered structure. Also, the lead time to become fully functional can be much longer. For instance, it may take decades for a watershed restoration project to reduce flood risk.
Despite these challenges, nature-based climate solutions are gaining credibility. They are increasingly being applied in major economies, as exemplified by the embrace of the “sponge city” concept in the People’s Republic of China. In addition, a thriving market for climate/green bonds holds the potential to channel significant private sector investment toward this approach.
As one of our experts, Professor Tony Wong from the Cooperative Research Centre for Water Sensitive Cities, noted during the workshop: “We should not try to build the forest around cities; instead, we build our cities around forests and natural landscape.”