Increasing interest in regime shifts in ecological and linked social-ecological systems (SESs) has placed a strong focus on the thresholds of change. However, research into this topic has been hampered by a lack of empirical data. This paper describes a developing database established to address this need. The database is freely available and comprises a set of summarized published examples and a searchable bibliographic database of publications on the topic. Thresholds in the database are characterized in terms of a standardized set of 24 descriptors, including the variables along which they occur, the variables that change, and the factors that have driven the change. Readers are encouraged to contribute new examples. Examples range from conceptual models to empirical evidence. The former predominate in the literature and, although they make valuable contributions and will continue to be included, the intention is build up the number of examples based on data. Examples are presented in terms of whether the threshold occurs in the ecological system, the social system, or both, and the direction of interactions between systems. The paper concludes with some initial observations on thresholds based on the examples included so far, and poses some questions for future research. Research on a typology of thresholds is a priority topic in the emerging area of "sustainability science" and it requires a rich database of empirical data.
Walker et al. (Thu,) studied this question.