Understanding the value and limits of nature-based solutions to climate change and other global challenges

Abstract

There is growing awareness that 'nature-based solutions' (NbS) can help to protect us from climate change impacts while slowing further warming, supporting biodiversity and securing ecosystem services. However, the potential of NbS to provide the intended benefits has not been rigorously assessed. There are concerns over their reliability and cost-effectiveness compared to engineered alternatives, and their resilience to climate change. Trade-offs can arise if climate mitigation policy encourages NbS with low biodiversity value, such as afforestation with non-native monocultures. This can result in maladaptation, especially in a rapidly changing world where biodiversity-based resilience and multi-functional landscapes are key. Here, we highlight the rise of NbS in climate policy-focusing on their potential for climate change adaptation as well as mitigation-and discuss barriers to their evidence-based implementation. We outline the major financial and governance challenges to implementing NbS at scale, highlighting avenues for further research. As climate policy turns increasingly towards greenhouse gas removal approaches such as afforestation, we stress the urgent need for natural and social scientists to engage with policy makers. They must ensure that NbS can achieve their potential to tackle both the climate and biodiversity crisis while also contributing to sustainable development. This will require systemic change in the way we conduct research and run our institutions. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.

Keywords: adaptation; ecosystems; mitigation; nature; restoration; sustainable development.

Figure 1.

Integrating NbS to climate change impacts into the social–ecological vulnerability framework. Ecosystem exposure is the extent to which systems are subject to pressures (floods, droughts, landslides, fires, etc.). It is determined by the intensity, duration and frequency of events, geomorphology and the extent of use and management of natural resources by human societies. Ecosystem sensitivity is the degree to which ecosystem structure and function alters as a result of perturbations. Ecosystem exposure combined with ecosystem sensitivity creates a potential impact. This is buffered over time by the adaptive capacity of the ecosystem. Both ecosystem sensitivity and adaptive capacity are determined by the diversity, heterogeneity and connectedness of the ecosystem and the characteristics and condition of its component species and habitats. Overall ecosystem vulnerability is shaped by the combination of potential impact and adaptive capacity. This ultimately affects the delivery of ecosystem goods and services upon which people and economies depend. In this way, ecosystem vulnerability affects socioeconomic vulnerability, i.e. the degree to which the social system is adversely affected by change. Socioeconomic sensitivity is also influenced by a range of social, political and economic factors. For example, corruption or low levels of health, education or employment, and a lack of economic diversification can increase socioeconomic sensitivity. Likewise, socioeconomic adaptive capacity, that can moderate the potential impact from social exposure and sensitivity, includes the ability to innovate (e.g. improving health, education and finding alternatives sources of income). NbS bring all these elements together and can, if implemented properly and equitably, decrease social–ecological vulnerability (see main text, and table 1). (Online version in colour.)