Climate change and urbanization have resulted in several societal challenges for urban areas. Nature-based solutions (NBS) have been positioned as solutions for enhancing urban resilience in the face of these challenges. However, the body of conceptual and practical knowledge regarding NBS remains fragmented. This study addresses this gap by means of a systematic review of the literature, to define NBS as a theoretical concept; its broader significance with respect to societal challenges; the key stakeholders in NBS planning, implementation and management; and major barriers to and enablers of NBS uptake. The results of this review reveal that, despite a lack of consensus about the definition of NBS, there is a shared understanding that the NBS concept encompasses human and ecological benefits beyond the core objective of ecosystem conservation, restoration or enhancement. Significant barriers to and enablers of NBS are discussed, along with a proposed strategic planning framework for successful uptake of NBS.

The applicability of steam activated pine and spruce bark biochar for storm water and wastewater purification has been investigated. Biochar samples produced from the bark of scots pine (Pinus sylvestrus) and spruce (Picea spp.) by conventional slow pyrolysis at 475 °C were steam activated at 800 °C. Steam activation was selected as a relatively inexpensive method for creating porous biochar adsorbents from the bark-containing sidestreams of the wood refining industry. A suite of standard analytical procedures were carried out to quantify the performance of the activated biochar in removing both cations and residual organics from aqueous media. Phenol and microplastics retention and cation exchange capacity were employed as key test parameters. Despite relatively low surface areas (200–600 m²/g), the steam-activated biochars were highly suitable adsorbents for the chemical species tested as well as for microplastics removal. The results indicate that ultra-high porosities are not necessary for satisfactory water purification, supporting the economic feasibility of bio-based adsorbent production.

Increasing global urbanization yields substantial potential for enhanced sustainability through careful management of urban development and optimized resource use efficiency. Nature-based solutions (NBS) can provide a means for cities to successfully navigate the water-energy-climate relationship, thus enhancing urban resilience. Implementation of NBS can improve local or regional economic resilience underpinned by the sustainable use of natural resources. The innovative governance, institutional, business, and finance models and frameworks inherent to NBS implementation also provide a wealth of opportunity for social transformation and increased social inclusiveness in cities. The ultimate benefit of NBS implementation in cities is increased livability, which is typically measured as a function of multiple social, economic and environmental variables. Given the range of different interventions classified as NBS and the cross-sectoral character of their co-benefits, different assessment schemes can be used to evaluate NBS performance and impact. Herein, performance and impact indicators within three robust NBS- and Smart City-related assessment schemes—Mapping and Assessment of Ecosystems and their Services (MAES), Knowledge and Learning Mechanism on Biodiversity and Ecosystem Services (EKLIPSE), and Smart City Performance Measurement Framework (CITYkeys)—were critically analyzed with respect to Sustainable Development Goal (SDG) 11, “Make cities and human settlements inclusive, safe, resilient and sustainable.” Each selected assessment scheme was benchmarked with respect to the Inter-Agency Expert Group on SDG Indicators' global indicator framework for the sub-objectives of SDG 11. The alignment between each of the selected NBS assessment schemes and the SDG indicator framework was mapped with particular emphasis on consistency with city-level framework indicators for each SDG 11 sub-objective. The results were illustrated as composite scores describing the alignment of the analyzed NBS and Smart city assessment schemes with the SDG 11 sub-objectives. These results facilitate NBS assessment scheme selection based on alignment between each analyzed assessment scheme and specific SDG 11 sub-objectives. Cities face multiple challenges amidst a complex hierarchy of legislative, regulatory and other stakeholder obligations. The present study showed that strategic selection of an NBS assessment scheme which closely aligns with one or more sub-objectives within SDG 11 can maximize operational efficiency by exploiting synergies between evaluation schemes.