The recent rapid, ubiquitous and global environmental changes require close exchange between knowledge holders, decisionmakers and policymakers to inform and support key decisions on the management of biodiversity and natural resources. Science, its approaches, results and recommendations are frequently associated with uncertainty, while stakeholders and practitioners often require clear and certain information; a situation that limits the communication between scientists and the aforementioned groups and therefore also restricts efforts regarding conservation and management of biodiversity. As part of WP4 Link environment to biodiversity: analyses of patterns, processes and trends , task 4.5 aimed at identifying and summarising existing sources of uncertainties alongside the biodiversity modelling process and finally at quantifying those uncertainties in terms of analyses and criteria of decision-making. The latter turned out to be a challenging task. The different existing approaches and frameworks in biodiversity modelling as well as the involvement of different scientific communities itself are too heterogeneous to gain a general directive to quantify uncertainty at this point. Therefore, the focus of task 4.5 was re-oriented; the partners worked on reviewing these heterogeneous sources of uncertainty and on assessing how these are considered and addressed in current research on biodiversity. The following three focal points were set: (1) The development of a conceptual framework integrating the existing sources of uncertainty that are linked to the modelling process to set a baseline for prioritisation and potential future quantification of uncertainty, which is based on the current state of recognition and incorporation of these sources. This also includes the identification of gaps in current data and methodologies leading to future improvements. (2) The development of coherent and straightforward tools and (statistical) methods to explicitly account for uncertainty in biodiversity models and to start closing the identified gaps. This task was approached in close collaboration with WP3 Improving tools and methods for data analysis and interface to utilize overlaps and synergies in both topics and involved partners. (3) As a perspective, we further provide some reflection on the main difficulties identified in the communication of uncertainties surrounding scientific results towards stakeholders and decision-makers of different levels. As this aim is a main objective of WP6 Stakeholder engagement and science-policy dialogue , we here focus on the communication, and especially the visualisation of uncertainties directly stemming from biodiversity modelling rather than from interactions within realms at the interface of science and policy.