What are Nature-Based Solutions ?

What are Nature-Based Solutions ?

The Nature-based Solution concept

Our societies are currently facing many challenges. Some are not new, such as food and water security, while others, more recent, are more directly linked to human activities, such as climate change. In this context, Nature-based Solutions, or NbS, provide solutions to these societal challenges by relying on what nature already provides. Several approaches that combine protection, management, and restoration of ecosystems already exist. The key novelty of the NbS concept is that such approaches must be beneficial to biodiversity while improving human well-being. For example, a mangrove forest fixes the coastline and thus protects it from possible flooding (which risk increases due to climate change), but it can also sequester four times more carbon than a rainforest per unit area. Therefore, protected, managed, or restored mangroves can help to mitigate and adapt to climate change. In addition, co-benefits in terms of biodiversity occur by providing habitat for numerous marine and terrestrial species.

Figure 1: Definition of NbS: From IUCN. (2020). Guidance for using the IUCN Global Standard for Nature-based Solutions: a user-friendly framework for the verification, design and scaling u of NbS. Source: https://doi.org/10.2305/IUCN.CH.2020.08.en

The term NbS was clearly defined by the International Union for Conservation of Nature (IUCN)[1] and the European Union (EU)[2] in an effort to bring together all ecosystem-related approaches already meeting this dual purpose of benefiting biodiversity and human well-being to answer to a societal challenge. This term is thus intended as an umbrella term.

What makes a Nature-based Solution?

The IUCN has defined 7 societal challenges to which NbS must respond: (1) climate change mitigation and adaptation, (2) food security, (3) water security, (4) disaster risk reduction, (5) human health, (6) economic and social development, and (7) environment degradation and biodiversity loss. In 2020, the IUCN has also published global standards that allow characterising protection, management, and restoration actions as NbS through 8 criteria. These criteria include the need to address at least one of the above societal challenges, as well as the benefit to biodiversity and human well-being through sustainable management and implementation. An NbS must also be designed at a large spatial (generally defined as land‑, freshwater- and seascape) and temporal scale (several decades) in partnership with all stakeholders for inclusive, sustainable, and integrated governance. In addition, this solution must be economically feasible and the positive effects quickly observable, but can also be adaptive, which makes its strength. Taking the example of a salt marsh that needs to be managed to limit the risk of flooding, one possible action is to plant and facilitate the development of vegetation capable of regulating the water flow. However, depending on the plant species, the growth of the plants can be more or less long. In this context, artificial management of the water flow can be set up so that positive effects on the scale of the first year can be observed while waiting for the natural action of the vegetation to be effective. Finally, to be recognised as an NbS, the effectiveness of the actions implemented and any land-use planning developed should be measurable. In this context, it is imperative to have tools capable of assessing the effectiveness of an NbS. These tools must be developed around scientific studies, based on in-depth knowledge of ecosystems and their services, as well as the links between biodiversity and environmental health in contexts of varying anthropic pressures. Further research is also needed to understand better the interconnection between biodiversity, climate change and provided services within ecosystems to recommend actions that could be an effective NbS in a specific area. 

Figure 2: The 8 criteria of the global standards for NbS published by the IUCN: From IUCN. (2020). Guidance for using the IUCN Global Standard for Nature-based Solutions: a user-friendly framework for the verification, design and scaling u of NbS. Source: https://doi.org/10.2305/IUCN.CH.2020.08.en

The way ahead for marine and coastal Nature-based Solutions

NbS can apply to both natural and modified ecosystems (such as urban areas). Currently, most NbS have been identified in urban and terrestrial environments and agriculture sector, while natural marine environments and their specificities are less considered and very few NbS have been recorded. One of the main reasons is that it is more challenging to implement and then evaluate out of sight large-scale actions in the ocean. The lack of basic knowledge on ecological responses to marine ecosystem-based approaches in terms of ecosystem service provision or biodiversity gain is also an obstacle to proposing relevant NbS in the marine context. MaCoBioS thus aims to address these knowledge gaps and disseminate the principles and purpose of NbS to coastal marine ecosystems’ stakeholders.

[1] “Nature-based Solutions are actions to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits. They are underpinned by benefits that flow from healthy ecosystems and target major challenges like climate change, disaster risk reduction, food and water security, health and are critical to economic development.” Source: https://www.iucn.org/theme/nature-based-solutions/about

[2] The Commission defines nature-based solutions as: “Solutions that are inspired and supported by nature, which are cost-effective, simultaneously provide environmental, social and economic benefits and help build resilience. Such solutions bring more, and more diverse, nature and natural features and processes into cities, landscapes and seascapes, through locally adapted, resource-efficient and systemic interventions.” Source: https://ec.europa.eu/info/research-and-innovation/research-area/environment/nature-based-solutions_en

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Why are kelp forest important ?

Why are kelp forest important ?

Kelp forests and their importance for nature and society

Kelp forests are often regarded as “underwater rainforests”. Formed by the dense growth of several kelp species, they produce a three-dimensional habitat and a highly productive system. Usually found in water temperatures below 20 °C, kelps are large brown algae that attach to the seafloor (‘benthic’). Not only can kelps grow amazingly fast in the right conditions – up to 30 cm per day – they can also reach 45 m long for the giant kelp. As well as providing plenty of surfaces and nooks and crannies for other species to settle on or in and live, they shelter coastlines from storms and help sequester or absorb carbon from the atmosphere, making them incredibly important societal resources.

Laminaria hyperborea kelp, Norway

Kelps as important biodiversity and feeding grounds

The forests created by kelps provide a home for a huge variety of different species, from other benthic algae to invertebrates, fish and marine mammals. Investigations along the Norwegian coast have shown a maximum of almost 100 000 small invertebrates connected to one single stipe (main stem) of the species Laminaria hyperborea. With on average 10 plants per m2, this makes up a very high diversity and abundance of animals which form the base of food webs up to fish and mammals. Many of these fish are then caught for food by humans.

The three-dimensional habitat of kelp forests also provides shelter for many species and make great places to hide from possible enemies. The holdfasts of kelps anchor them to the seafloor, and their branched root-like structure means several different species use these as habitat. For example, the edible crab (Cancer pagurus) usually lives inside this holdfast when it is young, protected from predators. You will often see a large holdfast housing many species of worms, brittle stars, molluscs, and crustaceans. The stipe and the fronds (leaf-like structures) of kelps provide additional types of habitats to different species. Usually overgrown by epiphytes – algae and animals that grow on a plant – up to 50 or 60 different species of algae, consisting of mostly red algae, can be found on any one stipe. These epiphytes provide an additional dimension to the kelp forest and, in turn, support many other animals with shelter, food and raw materials. For instance, many smaller crustaceans, such as the shrimp-like amphipods, use these algae as a substrate to build the small tubes they live in.

Brittle stars in a kelp holdfast, Norway

Kelps also provide valuable spawning and nursery grounds for numerous species of fish and shellfish, which go on as adults to become the foundation for many commercial and recreational fisheries, such as the Atlantic cod, Gadus morhua. These smaller fish then attract larger predators like seals, sharks, and sea birds who hunt around the kelp canopies.

Threats and changes to kelp forests

Globally, kelp forests are increasingly threatened by a variety of human impacts, including climate change and fishing/hunting, harvesting, eutrophication.

Being a cold-water species, kelp forests are sensitive to elevated temperatures. As ocean temperatures increase as a result of greenhouse gas emissions, massive kelp forest die-offs are increasingly likely, with their return questionable. In some places, such as in Australia and Tasmania, we have already seen that kelps have not returned to areas they were once abundant.

Fishing through kelp forests using destructive methods like bottom trawling has also been implicated in dramatic declines of kelps, such as in the UK, while predator removal from fishing/hunting has likely changed ecosystem structure in many kelp forests. Few large animals graze on fresh kelps except for sea urchins; however, these animals can devastate a kelp forest, grazing until only denuded rocks, or barren grounds, are left. When urchins are removed, vegetation often rapidly returns, although the animals take longer. The reason for this overgrazing is still under debate but, in most cases, it is probably caused by predator removal leading to an increase in urchin populations. The most well-known example of this comes from the west coast of Canada and the United States, where sea otters were extensively hunted. As their population declined, urchin populations increased and grazed down the kelp forest. After the hunting of otters was stopped, the kelp forest returned.

Sea urchins (Strongylocentrotus droebachiensis) grazing kelp forest in Northern Norway.

Kelps in our daily lives

Kelps are more important to our daily lives than you might think. In particular, they produce alginates to allow their flexible branches to withstand the constant movement from waves. This substance is widely used in pharmaceutical products, like pill coatings or toothpaste, and food production, including ice cream or beer.

The role of kelp forests in climate regulation

Marine macroalgae, such as kelps, play an important role in reducing the effects of climate change. Like plants on land, kelps photosynthesise to grow, absorbing carbon dioxide in the process. Globally, marine macroalgae may sequester around 170 million tonnes per year (range 61-268 tonnes C year−1, Krause-Jensen & Duarte, 2016), equivalent to more than 600 million tonnes of CO2 or 2% of global emissions annually. Healthy kelp grows fast and exports much of its biomass, via frond shedding, to the deep sea. Because deep-sea sediments have little direct contact with human activities, this “blue carbon” is trapped and stored for centuries.

While there will be no substitute for rapid reductions in greenhouse gas emissions to mitigate climate change, kelp forests provide a valuable addition to the arsenal of tools for reducing its effects. Therefore, understanding the impact changing environmental conditions will have on kelp itself is key to predicting future changes in its distribution and functions, including its blue carbon role. In particular, within MaCoBioS, we focus on exploring the evidence for ‘tipping points’ for different kelp species in Europe and developing models to predict future changes and identify potential management options, including Nature-Based Solutions, to mitigate the further loss of kelp forests.


Krause-Jensen, D., & Duarte, C. M. (2016). Substantial role of macroalgae in marine carbon sequestration. Nature Geoscience, 9(10), 737-742.

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