Over the past decade, citizen science has experienced growth and popularity as a scientific practice and as a new form of stakeholder engagement and public participation in science or in the generation of new knowledge. One of the key requirements for realising the potential of citizen science is evidence and demonstration of its impact and value. Yet the actual changes resulting from citizen science interventions are often assumed, ignored or speculated about. Based on a systematic review of 77 publications, combined with empirical insights from 10 past and ongoing projects in the field of citizen science, this paper presents guidelines for a consolidated Citizen Science Impact Assessment framework to help overcome the dispersion of approaches in assessing citizen science impacts; this comprehensive framework enhances the ease and consistency with which impacts can be captured, as well as the comparability of evolving results across projects. Our review is framed according to five distinct, yet interlinked, impact domains (society, economy, environment, science and technology, and governance). Existing citizen science impact assessment approaches provide assessment guidelines unevenly across the five impact domains, and with only a small number providing concrete indicator-level conceptualisations. The analysis of the results generates a number of salient insights which we combine in a set of guiding principles for a consolidated impact assessment framework for citizen science initiatives. These guiding principles pertain to the purpose of citizen science impact assessments, the conceptualisation of data collection methods and information sources, the distinction between relative versus absolute impact, the comparison of impact assessment results across citizen science projects, and the incremental refinement of the organising framework over time.

SummaryIncreasing attention is being paid to the importance and potential of crowd-sourced data to complement current environmental data-streams (i.e. in-situ observations and RS data). In parallel, the diffusion of Information Communication Technologies (ICTs) that are interactive and easy to use have provided a way forward in facing extreme climatic events and the threatening hazards resulting from those. The combination of these two trends is referred to as ICT-enabled ‘citizen observatories’ of the environment. Nevertheless, the success of these citizen observatories hinges on the continued involvement of citizens as central actors of these initiatives. Developing strategies to (further) engage citizens requires in-depth understanding of the behavioral determinants that encourage or impede individuals to collect and share environment-related data. This paper takes the case of citizen-sensed weather data using Personal Weather Stations (PWSs) and looks at the drivers and barriers for sharing such data via online amateur weather networks. This is done employing a behavioral science lens that considers data sharing a decision and systematically investigates the influential factors that affect this decision. The analysis and findings are based on qualitative empirical research carried out in the Netherlands, United Kingdom and Italy. Subsequently, a model was developed that depicts the main drivers and barriers for citizen participation in weather observatories. This resulting model can be utilized as a tool to develop strategies for further enhancing ICT-enabled citizen participation in climatic observations and, consequently, in environmental management

Floods are the natural hazards that are causing the most deaths worldwide. Flood early warning systems are one of the most cost-efficient methods to reduce death rates, triggering decisions about the evacuation of exposed population. Although previous studies have investigated the effect of human behaviours on evacuation processes, studies analysing a combination of behaviours, flood onset and warning timing are limited. Our objective is to explore how changes on the aforementioned factors can affect casualties. This is done within a modelling framework that includes an agent-based model, a hydraulic model, and a traffic model, which is implemented for the case study of Orvieto (Italy). The results show that the number of casualties is most impacted by people’s behaviour. Besides, we found that a delay of 30 min in releasing the warning can boost the number of casualties up to six times. These results may help managers to propose effective emergency plans.

In response to the need for approaches to understand how citizen science is currently influencing environmental policy and associated decision making, we devised the Citizen Science Impact StoryTelling Approach (CSISTA). We iteratively designed instruments to be used as tools primarily for citizen science practitioners seeking to understand or communicate policy impacts. We then trialled the CSISTA and associated instruments on four exemplary citizen science initiatives, using different forms of inquiry and collaboration with respective initiative leaders. In this paper, we present CSISTA, with details of the steps for implementing inquiry and storytelling instruments. Additionally, we reflect on insights gained and challenges encountered implementing the approach. Overall, we found the versatility and structure of CSISTA as a process with multiple guiding instruments useful. We envision the approach being helpful, particularly with regards to: 1) gaining an understanding of a citizen science initiative's policy and decision-making impacts; 2) creating short policy impact stories to communicate such impacts to broader audiences; or 3) fulfilling both goals to understand and communicate policy impacts with a unified approach. We encourage others to explore, adapt, and improve the approach. Additionally, we hope that explorations of CSISTA will foster broader discussions on how to understand and strengthen interactions between citizen science practitioners, policy makers, and decision makers at large, whether at local, national, or international scales.