Over the last decade, the potential of nature-based solutions (NBS) has been recognized to support climate change adaptation, by promoting sustainable urban planning. Nevertheless, a wider uptake of such solutions in urban areas faces different challenges and barriers. A comprehensive mapping of available NBS impact assessment methods could help to accelerate this process. There is, however, a lack of comprehensive systematization of economic analysis. This research aims to provide an overview of NBS impact evaluations by assessing how the scientific literature integrates such economic analysis into urban planning adaptation. A systematic review approach has been used to discuss the role of NBS in climate change adaptation. This review presents two main stages. Firstly, it identifies the biophysical–economic assessment of NBS adaptation measures to reduce urban flood extremes in coastal cities. Secondly, the NBS approaches were categorized based on the biophysical benefits (in terms of flood-risk reduction) related to each specific solution and the subsequent economic evaluation of such implementations. This research review revealed a low-level gap of integration between climate change issues and NBS analysis (i.e., it is commonly used as background condition). Most publications provide NBS biophysical impacts assessment, without combining these results with economic evaluation of the flood damages to finally achieve the avoided cost due to the implementation of such solutions. This work shows the growing interest on further research to develop spatially integrated environmental–economic assessment of NBS implementation, by highlighting the needs and opportunities of a trans-disciplinary approach to support policy-making in the framework of urban climate change adaptation.

This article explores general concepts related to the diffusion of innovations theory (DoI) and its use regarding the adoption of nature-based solutions, specifically green roofs, in urban areas by private house/property owners in the city of Eindhoven (Netherlands). Given the gap in knowledge on the potential for the adoption of green roofs by private house/property owners as well as barriers and enablers to their implementation from the DoI perspective, we used a model for predicting the adoption of innovations (ADOPT). Results show that the predicted peak adoption level is 3% and that the time to peak adoption level is 17 years. However, the level of adoption can be significantly enhanced by increasing profit benefit (i.e., cost savings) in the years that they are used (+19 percent points adoption), reducing risk exposure (+17 percent points adoption), and improving ease and convenience (+15 percent points adoption), while the time to peak adoption level can be reduced by enhancing relevant and existing skills and knowledge (−3 years), simplifying trialability and innovation complexity (−2 years), and increasing observability (−1 year). Hence, key factors affecting the adoption of green roofs by private house/property owners have been identified, contributing to the formulation of urban climate change adoption strategies.

The Coronavirus Disease 2019 (COVID-19) pandemic that spread through the world in 2020 had a major effect on academia. Research projects relying on participatory methods and action research approaches were especially harmed by the restrictions and changes the situation imposed. This study performs a rapid literature review to identify common themes in the narratives of published studies concerning the difficulties of carrying-out participatory research during the COVID-19 pandemic. Perceptions and experiences of the authors of these studies are compiled and summarized. Additionally, insights and lessons learned from two projects in which the authors of this study participated are discussed and used to establish a comparison with the common challenges found in the literature. Over 90% of authors experienced challenges related to digitalization and methodological changes, 70% encountered difficulties with organizational and operational aspects of research, and over 30% felt that personal challenges, as well as issues with participatory aspects of research, were significant. On a positive note, almost 40% of authors from our sample recognize that the pandemic also brought unexpected benefits, such as a reduction in logistical expenses, and the creation of new opportunities for participation. This study adds to the growing body of literature regarding the effects of the COVID-19 pandemic on the research community. Additionally, it comments on the adaptation of participatory action research methods for added sustainability and social inclusion in the face of global crises.