Professor Harriet Bulkeley, Durham University – Written evidence (NSD0015)


Evidence from NATURVATION (H2020 grant agreement No. 730243) by Prof. Harriet Bulkeley, Durham University


While there are multiple definitions of nature-based solutions, together they point to the importance of the multiple benefits that working with nature can provide. The European Commission, for example, 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.[1] Indeed the potential strength of nature-based solutions lies in their capacity to generate outcomes that address multiple challenges. Evaluating the contribution of nature-based solutions to climate mitigation should be undertaken with this perspective. While nature-based solutions may be less efficient in direct comparison with other sequestration and storage options, their wider contribution to biodiversity, SDGs, social justice and economic regeneration needs to be bought into the evaluation. This is not only a matter of improving the accuracy of assessment, but is also critical because climate solutions are far more likely to be adopted – and crucially, stay adopted – if they also contribute to multiple other ‘co-benefits’ (e.g. clean air, health, resilience, economic development). This ‘added value’ is not only ‘nice to have’ but crucial for moving from goals to implementation.


  1. What is the potential scale of the contribution that nature-based solutions can make to decarbonisation in the UK?


Which ecosystems are most relevant to the UK for nature-based solutions, and which have the largest potential to sequester carbon or reduce emissions?

The relevance of different ecosystems and landscapes for nature-based solutions relates to the potential of such interventions to offer significant benefits for climate change alongside other environmental and social challenges facing places and communities in the UK. There is a growing body of evidence that suggests that nature-based solutions are highly relevant for urban landscapes in the UK because their multi-functional benefits enable multiple urban challenges to be addressed simultaneously. Research by the NATURVATION project analysing over 770 Functional Urban Areas in Europe[2] and at a detailed scale for three European cities demonstrates that nature-based solutions can address climate adaptation and mitigation needs for cities, while also contributing to the protection and restoration of biodiversity and enabling communities to access nature ‘on their doorstep. Comparative analysis of 54 case-studies of urban nature-based solutions globally demonstrates that they can contribute to economic development and social justice,[3] and that they enable cities to address critical challenges and build resilience.[4]


If nature-based solutions are going to hold relevance to the UK population, they need to be implemented in cities so that individuals and communities can benefit from them on a daily basis and also come to learn the value of nature for the future. Urban nature-based solutions are particularly important in terms of addressing long-term inequalities in relation to access to nature and protection from the risks of climate change in cities. Research shows that current access to green space in the UK is highly uneven,[5] and this in turn is likely to mean that communities have different protection from e.g. heat and flood risk under a changing climate.[6] Equally important, recent research shows that coming into contact with nature on an everyday basis can contribute to enhancing environmental awareness and action. The uneven urban geographies of nature currently mean that this experience and connection to nature is not available to all communities, depriving them of not only the direct benefits of nature but of ways to form new knowledge and relationships to nature for the future.


In terms of the scale of the potential for urban nature-based solutions to store carbon, analysis conducted by the NATURVATION project by PBL The Netherlands Environment Agency of 47 Functional Urban Areas in the UK estimates that 610 Mton carbon are (currently) stored across these cities, with a mean of 7.87 kton carbon stored per km2 (or 78.7 ton/ha) of urban area. Highest total carbon storage is estimate for Aberdeen (58 Mton carbon) and London (50 Mton carbon), while highest carbon densities (per km2 urban areas) are estimated for Hastings and Guildford (both 10 kton carbon/ km2). In short, the land surrounding just 47 of the UK’s cities currently stores more carbon than we emit in any one year. Development pressure on this land to convert it to housing stock may come to be an important source of carbon by removing such sinks. Preserving urban green space, especially in urban hinterland areas, is then a key policy choice for securing the UK’s carbon store.


By implementing additional urban parks and increasing the tree density in the cities[7] (using only land available for such purposes) the total carbon storage increases by 13% (up to 690 Mton) and a mean carbon storage of 8.75 kton per km2 (or 87.4 ton/ha) is estimated. Under this ‘greening’ scenario, the highest total carbon storage is estimated for Aberdeen and Newcastle upon Tyne (69 and 59 Mton carbon resp.), while highest carbon density is estimated in Dundee City and Glasglow (both 11 kton). This suggests that there are several cities where there is particular potential to increase urban nature-based solutions using existing ‘green spaces’ in the city. Land conversion – moving from grey infrastructure (e.g. pavements, car parks, roofs) to increase the capacity for nature-based solutions could increase carbon storage further.


  1. What frameworks already exist for the regulation and financing of nature-based solutions?


Are there good examples of nature-based solutions already being undertaken in the UK or elsewhere, and what can we learn from them?

The NATURVATION project has developed a database of over 1000 nature-based solutions projects being undertaken in cities globally ( which demonstrates the variety of initiatives being taken in diverse urban contexts by multiple actors.[8] Detailed analysis of this database together with 54 in-depth international case-studies has led to the identification of twelve different governance arrangements and eight business models that are successfully being used to implement nature-based solutions.[9] This evidence shows the critical importance of both co-governance and co-finance for nature-based solutions – as interventions that will always yield public and private benefits across multiple policy challenges, it is crucial to have intermediary organisations in place that can bring together different actors who may not often collaborate with one another. There is no ‘one size fits all’ business model that can generate and capture diverse value streams (e.g. for risk reduction that benefits insurance or utility companies and health benefits that are valued by public health providers and local communities, alongside carbon sequestration and storage). Rather, governance and financing arrangements that enable these business models to be ‘stacked’ together and co-ordinated are needed to realise the investment required for nature-based solutions and ensure that their full value (monetary and non-monetary) are captured.


We also find that while nature-based solutions can be a powerful way of addressing issues of social and environmental justice, they do not necessarily do so and indeed they can be designed and implemented in ways that exacerbate urban inequalities, e.g. through green gentrification. Analysis shows that nature-based solutions increase land values,[10] and in this way can put pressure on housing markets which leads to the displacement of existing residents.[11] Equally, nature-based solutions can be designed to address climate change or enhance the economic attractiveness of urban areas, without giving due consideration to the needs and values of local communities. Such interventions not only serve to exacerbate social inequality, but also frequently meet with strong opposition. Even though participatory approaches are often used, they do not necessarily explicitly focus on social justice. New tools and techniques are needed which explicitly bring questions of social inequality into consideration in the planning and design of nature-based solutions.[12] While this research has focused on urban areas, we believe that this will be equally relevant in rural communities who must be involved in determining the futures of their communities and landscapes.


How should a hybrid public-private financing model be regulated? How should any carbon offsetting markets be regulated to ensure that they prioritise and support well-designed and effective nature-based solutions?

Both hybrid public-private financing and carbon offset markets have been in place for over two decades. To date these forms of climate response have largely been regulated through either: (a) voluntary standards (e.g. used by NGOs/investment community to hold corporate and government actors to account; or (b) the REDD+ mechanisms of the UNFCCC. Further strengthening these mechanisms and broadening the types of nature-based solutions that they include (e.g. away from a focus only on forestry/land use in the REDD+ mechanism), especially in terms of standards and principles for investment, is likely to be the most successful approach. There is evidence that the financial sector is moving forward with this now, through the Taskforce on Nature-related Financial Disclosure (www.tnfd) as is the EU through its Taxonomy (though note that the range of nature-based solutions included in the Taxonomy is currently rather narrow).


  1. Who are the key stakeholders for the implementation of nature-based solutions in the UK? How can stakeholders’ expertise and concerns inform the incentives and requirements for implementing nature-based solutions?


Are there examples of projects which have engaged with stakeholders and local communities to implement nature-based solutions successfully, and what can we learn from them?

There is now an extensive evidence base of nature-based solutions projects that have been developed with local communities in cities across Europe, as documented by NATURVATION ( and reported at Network Nature ( A recent review of a decade of work with communities on nature-based solutions found an overly narrow emphasis on co-production approaches, which can be effective but often serve only to include ‘the usual suspects’ in their approaches and are limited in their applicability due to the time and resources required for their implementation.[13] This evidence suggests that it will be important to use a range of approaches to engage communities, with a particular focus on mechanisms that are explicitly designed to address issue of social inequality. It is also critical to work with existing mechanisms – such as within the planning system – while engaging trusted actors at the community level (e.g. youth groups, religious leaders, museums and gardens, schools, wildlife groups, environmental organisations).


  1. How should implementation of nature-based solutions be integrated with other government policies for landscapes and seascapes, for example, agricultural, forestry, and land-use planning policies?


How could nature-based solutions implementation contribute to the UK’s goals surrounding biodiversity, the preservation of nature, and adaptation to climate change?

Nature-based solutions have significant capacity to address adaptation to climate change, particularly in urban areas – where the vast majority of people and infrastructure that need increased resilience to climate change are based. Evidence from the NATURVATION project suggests that green roofs are the most effective solution for addressing the multiple challenges of heat risk, excess water and carbon storage simultaneously, although other nature-based solutions are also effective in all three areas. The potential benefits of nature-based solutions depend crucially on the amount of space that is made available, the capacity of individual interventions and the connectivity between them. At present, most nature-based solutions are planned and implemented in a piecemeal fashion and their full potential is likely only to be realised if they are designed and implemented as a form of urban infrastructure.


Evidence from the NATURVATION project also shows that urban nature-based solutions are being used to address the goals of conserving and restoring nature, whilst also generating further benefits to society through enhancing nature’s contribution to people. Analysis of a sample of 199 case-studies from the Urban Nature Atlas that were explicitly intending to address the challenge of biodiversity shows that 174 have goals that focus on conservation, while 181 are seeking to enhance nature’s contribution to people through interventions that allow society and nature to thrive.[14] Conservation efforts are most often focused on ecosystems (rather than specific species or the conservation of genetic biodiversity). Besides descriptive goals for habitat protection and enhancement, Xie and Bulkeley (2020) find that a significant number of urban nature-based solutions projects have set quantitative targets for their conservation and restoration effortsamong the 93 ecosystem-based NBS projects that involved large urban parks, 52 projects had explicit quantitative targets.” Their analysis found that restoration has to date received much less specific attention in nature-based solutions projects, yet where it is in place there is significant potential for nature-based solutions to rehabilitate and restore degraded ecosystems in cities. A particular focus in the cases studied is on nature-based solutions that intend to restore rivers, streams and estuaries in urban areas through the re-naturalization of water courses/riverbeds or restoring ecological connectivity. Their findings echo those reported by the IUCN that nature-based solutions “allows us to achieve many otherwise conflicting objectives.[15]


It is also important to recognise that nature-based solutions can help to realise the goals of the UK government and the international community to address the indirect drivers of biodiversity loss. According to IPBES Global Assessment, the most important indirect drivers of biodiversity loss include land conversion, climate change, (over) consumption, waste and pollution, as well as a lack of knowledge about, and engagement with, nature amongst the public. Nature-based solutions that can provide a direct connection to nature, especially amongst urban communities, are likely to support a shift in values towards and action for nature which may in turn support a shift away from unsustainable consumption practices.[16] Nature-based solutions that support the amelioration of air and water pollution, or which serve to replace carbon-intensive materials (e.g. concrete) with natural materials that have a lower carbon footprint (e.g. sustainable urban drainage systems) can all serve to reduce the indirect drivers on biodiversity loss whilst also tackling climate change.


Which ongoing governmental plans, policies, and strategies are relevant to nature-based solutions, and can they be better coordinated?

When nature-based solutions are positioned not only as a form of climate mitigation, but as a new form of infrastructure and as part of urban development the number of governmental plans, policies and strategies which are relevant to their implementation and mainstreaming grows exponentially. The Biodiversity Net Gain approach will be one crucial means through which nature-based solutions can be developed that address both climate change and biodiversity and, if used progressively, could be a means through which to provide new green spaces for urban communities that currently do not have access to nature. Biodiversity Net Gain could be extended to other development projects (e.g. commercial or industrial development) and to infrastructure projects in order to further support nature-based solutions. Building regulations are currently lagging behind the development of nature-based solutions, e.g. in terms of green roofs and walls, or requirements to use nature-based solutions to improve the thermal efficiency of buildings or to provide cooling instead of (GHG powered) air conditioning.


9 September 2021


[2] NATURVATION (2021) Briefing Note: Mapping Benefits of NBS in 775 Urban Areas – Background Information, March 2021

[3] Kiss, B., Sekulova, F. & Kotsila, P. (2019) International Comparison of Nature-Based Solutions. Naturvation Project Report. NATURVATION

[4] McCormick, K. and Kiss, B. (2019) Taking Action for Urban Nature: Innovation Pathways Directory, NATURVATION

[5] Groundwork (2021) Out of Bounds: Equity in Access to Urban Nature

[6] McDonald RI et al. (2021) The tree cover and temperature disparity in US urbanized areas: Quantifying the association with income across 5,723 communities. PLoS ONE 16(4): e0249715.

[7] In the green scenario, we simulated the implementation of additional trees within the city by increasing the tree cover density per urban fabric class to the 95th percentile of the urban LULC specific tree cover density values across all cities. For the UK cities, this means approx. there is an average increase of the tree cover density by 15% (highest increase is seen within existing forest which increase tree coverage by around 20%; lowest increase (0.5%) in existing industrial, commercial and public units); Note: the actual overall increase is probably a bit higher as I excluded here the additional trees from the conversion of certain urban LULC to new ‘greener LULC’; e.g. new green residential areas on former construction sites or new forests on former land without current use.

[8] Almassy, D. et al. (2018). Urban Nature Atlas: A Database of Nature-Based Solutions Across 100 European Cities. NATURVATION.

[9] Bulkeley, H. (2019) Effective Governance Solutions & Toxopeus, H. (2019) Business Model Catalogue

[10] M. Bockarjova et al. (2020) Property price effects of green interventions in cities: A meta-analysis and implications for gentrification, Environmental Science & Policy,Volume 112, Pages 293-304,

[11] Isabelle Anguelovski et al. (2018) New scholarly pathways on green gentrification: What does the urban ‘green turn’ mean and where is it going? Progress in Human Geography, 43 (6): 1064-1086

[12] Emilia Oscilowicz, Isabelle Anguelovski, Helen Cole, and Ana Cañizares (2021) Policy and Planning Tools for Urban Green Justice, BCNUEJ, Autonomous University of Barcelona,

[13] Bulkeley, H. (2020) Nature-based solutions towards sustainable communities: analysis of EU-funded projects, European Commission Directorate General Research and Innovation,

[14] Xie L and Bulkeley H. (2020). Nature-based solutions for urban biodiversity governance, Environmental Science & Policy 110: 77–87

[15] Addy, S., Cooksley, S., Dodd, N., Waylen, K., Stockan, J., Byg, A., and Holstead, K. (2016) River Restoration and Biodiversity: Nature-based solutions for restoring rivers in the UK and Republic of Ireland. CREW reference: CRW2014/10.

[16] Bulkeley, H., Kok, M. and Xie, L. (2021) Realising the Urban Opportunity: Cities and Post-2020 Biodiversity Governance, PBL The Netherlands Environmental Assessment Agency