What are nature-based solutions?
Nature-based solutions are actions to protect, sustainably manage, or restore natural ecosystems, that address societal challenges such as climate change, human health, food and water security, and disaster risk reduction effectively and adaptively, simultaneously providing human well-being and biodiversity benefits. For example, a common problem is the flooding in coastal areas that occurs as a result of storm surges and coastal erosion. This challenge, traditionally tackled with manmade (grey) infrastructure such as sea walls or dikes, coastal flooding, can also be addressed by actions that take advantage of ecosystem services such as tree planting. Planting trees that thrive in coastal areas – known as mangroves -- reduces the impact of storms on human lives and economic assets, and provides a habitat for fish, birds and other plants supporting biodiversity.
Do nature-based solutions help fight climate change?
Estimates suggest that nature-based solutions can provide 37% of the mitigation needed until 2030 to achieve the targets of the Paris Agreement. How can this be done? If you plant trees, they’re going to soak up carbon. For example, restoring native forest at the margins of the river to avoid landslides can also act as a carbon sink. Climate-smart agriculture is another example that enables farmers to retain more carbon in their fields as they produce crops. Decreasing deforestation is another way to benefit from nature-based solutions – for example, by paying farmers not to cut down the forest preserves ecosystem services such as carbon sequestration, provision of clean drinking water, and reduction of river sedimentation downstream.
Nature-based solutions also play a key role in climate change adaptation and building resilience in landscapes and communities. Several nature-based solutions are being used by the World Bank to help manage disaster risk and reduce the incidence and impact of flooding, mudslides, and other disasters. They are a cost-effective way of addressing climate change while also addressing biodiversity and land degradation. You can address several problems at once.
But it’s not automatic that everything you plant becomes a nature-based solution that contributes to biodiversity – for example, planting trees that are not from the region and are toxic to local animals would not generate biodiversity benefits.
Estimates suggest that nature-based solutions can provide 37% of the mitigation needed until 2030 to achieve the targets of the Paris Agreement.
Where are World Bank projects incorporating nature-based solutions?
In FY20, the nature-based solutions portfolio of the World Bank included 70 projects– with many focusing on water and disaster risk management. We would like more projects to include nature-based solutions in other topic areas as well. To this end, we have been rolling out training for World Bank staff, with the goal of scaling up country-level support. The World Bank is committed to address the two intersecting global crises the world is experiencing: the climate crisis and the biodiversity crisis.
Let me give you a couple of examples: In Burundi, forests have been cleared and crops have been grown on steep hillsides without controlling erosion. As a result, the country has experienced more frequent landslides and floods and these have been made worse by the torrential rains and droughts associated with climate change. We’re supporting a project that is constructing nearly 8,000 hectares of terraces on hillsides, using vegetation at critical points to control soil erosion, increase soil moisture, and reduce runoff. Farmers are planting tree crops, soil-stabilizing grasses and fodder crops to protect topsoil and make the land more productive for farming.
In Colombo, Sri Lanka, we’re supporting a project pioneering the use of urban wetlands as a nature-based solution. Wetlands reduce flood risk by holding excess water, but the holding capacity of Colombo’s wetlands dropped by 40% over a decade. At the same time, climate change and sea-level rise increased the city’s vulnerability to flooding. The project used green and grey infrastructure to restore and protect the wetland and maintain its hydraulic integrity. This reduced flood risk for more than 200,000 city residents and provided the entire city with a better quality of life. The wetlands also sequester carbon and regulate the local climate, which has helped reduce the use of air conditioning near wetland areas. The project improved water quality and wastewater treatment, and the city’s Beddagana wetland has been turned into a park and wildlife sanctuary.
In the Zhejiang Qiandao Lake and Xin’an River Basin, China, we’re supporting integrated pollution and watershed management, to help increase access to improved water supply. The lake is a main source of potable water for many cities along the river basin, but rapid development, agricultural production, and tourism growth have increased water pollution. The project is implementing nature-based solutions such as climate-smart farming, environmentally sustainable forest management, restoration of wetlands and degraded forests, as some of the interventions seeking to improve the water quality in the lake.
All pathways to achieving the Paris Agreement include protection of forests and conservation, restoration, and sustainable use of natural ecosystems. Nature-based solutions offer a way of addressing the climate and biodiversity crises in a synergetic and cost-effective manner.
How do we measure results from nature-based solutions?
An evidence-based approach to managing, and measuring results from, nature-based solutions is paramount. This means monitoring and evaluation throughout the intervention cycle, drawing on science and data, as well as local and indigenous knowledge. What exactly needs measuring? This depends on the societal challenges the nature-based solution set out to address. If the goal is to mitigate climate change, the equations, the protocols, and the systems are well established to measure the results - with carbon dioxide (CO2) being the basic metric used. A ton of CO2 equivalent sequestered in a restoration project Brazil has the same effect on greenhouse gas concentration in the atmosphere as a ton of CO2 sequestered in a reforestation project in Russia.
What is critical is to look beyond climate and to also measure (and monetize – for example through environmental markets) the other benefits that the nature-based solution is delivering. For instance, when it comes to measuring the impact on biodiversity, the task is more complicated and multi-dimensional. Ecosystems are highly complex and dynamic systems; and there is no single high-level metric or a global goal on biodiversity equivalent to keeping the global warming below 1.5°C above pre-industrial levels in the climate realm. However, projects have a range of indicators available to them, such as trends in (threatened) species populations and the provision of critical ecosystem services – for example water quality and predictability in a watershed that benefitted from restoration of reforestation. Since biodiversity is irreplaceable and its loss may be irreversible (IPBES 2019), project results can be quite localized in nature.
For the World Bank, biodiversity and ecosystem services loss is a development issue and for this reason the institution has invested in nature for more than three decades. At present, we are working with other multilateral development banks to improve the way biodiversity benefits are assessed in development portfolios and in the broader financial markets. The stakes are high. The risks that climate change poses to global development are significant, and so are the risks of global biodiversity and ecosystem loss. All pathways to achieving the Paris Agreement include protection of forests and conservation, restoration, and sustainable use of natural ecosystems. Nature-based solutions offer a way of addressing the climate and biodiversity crises in a synergetic and cost-effective manner.
