This deliverable focuses on the creation of a current knowledge and research needs inventory for Nature-Based adaptation Solutions (NbaS). Carried out as part of Action A2 of the ARTISAN project, it aims to: (i) provide a multiscalar (international, regional and national) review of the current NbaS, (ii) identify and list research limitations and gaps, and (iii) propose perspectives for bridging the identified gaps and for developing further knowledge on NbaS. For the international scale, reports issued from the United Nations Framework Convention on Climate Change (UNFCCC), United Nations Environment Programme (UNEP) and the International Union for Conservation of Nature (IUCN) were examinated. The regional scale (Europe) was studied using the works of research projects funded udner the H2020 programme, while the national scale (France) was investigated using scientific literature from the SCOPUS database. The rationale behind the multiscalar approach articulates around two main ideas: (i) understanding and studying the transition from NbS to NbaS and (ii) situate the current state and progress in each scale and compare it with those of the other levels. Consequently, an inventory simultaneously grouping individual and multileveled current knowledge and research needs is provided. The main findings and conclusions of this work are summarized below. For more detailed information per scale, each chapter presents a separate section for analysis.