The Potential for Nature-Based Solutions Initiatives to Incorporate and Scale Climate Adaptation

1. Introduction

1.1 Definition and Evolution of Nature-Based Solutions for Adaptation

In the early 2000s, experts reconceptualized humans’ relationship to nature-based solutions (NBS) to shift our understanding of our role from passive beneficiaries of nature conservation to proactive participants in nature protection, management, and restoration to address societal challenges (Cohen-Shacham et al. 2019). Today, NBS is used as an umbrella term that captures several approaches aiming to reverse natural resource degradation and biodiversity loss while promoting United Nations (UN) Sustainable Development Goals (SDGs) and at times building resilience to climate change impacts. These approaches include ecosystem-based adaptation, ecosystem-based mitigation, eco-disaster risk reduction, natural and/or green (and blue) infrastructure, natural climate solutions (focused on climate mitigation and carbon sequestration), engineering with nature, nature-based flood protection, and re-naturing (Cohen-Shacham et al. 2019).

A clear, universal definition of NBS does not exist, but definitions by the International Union for Conservation of Nature (IUCN), the European Commission, and the UN all highlight these solutions as powerful tools that in many cases can increase resilience and biodiversity while providing co-benefits for humans (Calliari et al. 2019; Kapos et al. 2019).

Nature and the ecosystem services it provides underpin human society—and, if managed correctly, can be the first line of defense against extreme weather events and other climate risks, such as desertification and sea level rise (Kapos et al. 2019). Although using NBS approaches to adaptation are widely practiced by international development and climate adaptation practitioners, only recently have the broader climate mitigation and conservation communities begun to better recognize the potential of ecosystem services to help meet development and climate adaptation goals (Igoe 2019).

Even though cities and countries are showing interest in nature-based solutions for adaptation, they do not always have the technical expertise or financial and other resources to plan for and implement adaptation measures, and projects are often done on a pilot basis or in an ad hoc manner (Kapos et al. 2019). NBS initiatives could tap into the knowledge and tools employed by the adaptation community to mainstream NBS for adaptation across sectors to increase the use of biodiversity and ecosystem services to help people adapt to climate change effects. This paper aims to shed light on how multi-partner NBS initiatives can contribute to adaptation solutions, as some already have, and take advantage of existing opportunities to do more.

For the purposes of this working paper, NBS are defined as actions that protect, sustainably manage, and restore natural and modified ecosystems to address societal challenges effectively and adaptively, and that simultaneously provide human well-being and biodiversity benefits (IUCN n.d.). Adaptation is defined as the process of adjusting to actual or expected climate change and its effects, the process of moderating or avoiding harm, and the ability to exploit beneficial opportunities (IPCC 2014). Resilience is the ability of a system to cope with great change or disruption (adapted from IPCC 2018).

1.2 NBS for Adaptation Bring about Many Co-benefits

The most common types of climate-related hazards to which NBS are applied are coastal threats, flooding, landslides, drought, and rising temperatures (Kapos et al. 2019). Examples of co-benefits of adopting an integrated approach to climate, development, and nature include economic savings and efficiency gains from pooling resources, and unlocked social and environmental co-benefits. Negative trade-offs can be lessened or avoided by considering how climate is expected to change in the coming years and decades, and building in respective decisions and measures to protect against these effects.

Although not all NBS activities contribute to adaptation,1 many of them can support adaptation outcomes, in terms of protecting people and natural systems from both shorter-term hazards such as extreme heat days and longer-term threats like sea level rise and desertification (see Figure 1). This protection is especially relevant for equity reasons, given that marginalized groups, including many communities directly dependent on natural resources, are highly vulnerable to both climate change and environmental degradation. NBS can provide powerful societal benefits to vulnerable groups, such as access to water and firewood, in a way that is fair and equitable while promoting transparency and participation (Cohen-Shacham et al. 2019; IUCN 2020). Because NBS interventions often provide services for distant communities, cities, and governments, it is important to provide a clear participatory and representative process that involves local actors in decision-making, negotiations, and compensation mechanisms to prevent losses to the communities living in or near the intervention sites (Cohen-Shacham et al. 2019). Relatedly, green infrastructure can help reduce health inequalities by more fairly distributing health benefits to all of society, such as through nature-based water management techniques or green urban spaces (Pepinster 2021). Examples of overarching adaptation outcomes include enhanced food, water, and livelihood security; protection against flooding, drought, and disasters; and improved human health.

Figure 1 | Across Ecosystems, Different Nature-Based Solutions Can Work Together to Build Climate Resilience

Source: Bapna et al. 2019.

Research indicates that NBS can create or enhance natural buffers against extreme weather events and climate fluctuations that can damage physical assets and negatively impact livelihoods (Seddon et al. 2020). They can be as or more effective than alternative interventions to address climate impacts (World Bank 2020; Chausson et al. 2020; Kapos et al. 2019). For example, when compared with gray infrastructure, mangrove forests can provide a cost-effective green means of coastal protection from storms and hurricanes. One study found that, across 59 countries, mangroves can help save an estimated US$65 billion annually in avoided losses in infrastructure and human systems, including health (Earth Security 2021).

Similarly, adequate watershed management and wetland rehabilitation can prevent loss of life and property by minimizing damages from extreme storms, soil erosion, and landslides. Agroforestry, natural reservoirs, and sustainable agricultural practices can protect against seasonal variability, pests and disease, and rising temperatures, thus decreasing food insecurity and crop losses.

1.3 NBS for Adaptation Are Cost-Effective

NBS have frequently been recognized as an equal or more cost-effective approach than traditional business-as-usual solutions (e.g., built “gray” infrastructure such as dikes, dams, reservoirs, pipes, and seawalls) (UNEP 2018). The Organisation for Economic Co-operation and Development found, for example, that NBS were two to five times more cost-effective than gray infrastructure across 52 coastal defense projects in the United States and were more effective in defending against waves up to half a meter high and at increased water depth (OECD 2020). Leveraging natural capital to protect against water-security threats—projected to rise in the coming decades—represents a potential $3 trillion in avoided replacement costs by 2050 (Vörösmarty et al. 2021).

Likewise, a new study by the International Institute for Sustainable Development calculates that using nature in infrastructure projects can save governments and investors $248 billion annually, and that NBS can be up to 50 percent cheaper than gray infrastructure while providing the same infrastructure services (IISD et al. 2021). Economic savings are especially important for the world’s most climate-vulnerable countries, which are typically the least able to afford the economic brunt of climate impacts (Bapna et al. 2019).

Given the potential to expand NBS initiatives’ outcomes by broadening their missions to include adaptation, this paper identifies opportunities and support needed for initiatives to integrate adaptation as well as opportunities to accelerate adaptation action.

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