Introduction: Handling uncertainty in the geosciences: identification, mitigation and communication.

In the geosciences, data are acquired, processed, analysed, modelled and interpreted in order to generate knowledge. Such a complex procedure is affected by uncertainties related to the objective (e.g. the data, technologies and techniques employed) as well as the subjective (knowledge, skills and biases of the geoscientist) aspects of the knowledge generation workflow. Unlike in other scientific disciplines, uncertainty and its impact on the validity of geoscientific outputs have often been overlooked or only discussed superficially. However, for geological outputs to provide meaningful insights, the uncertainties, errors and assumptions made throughout the data acquisition, processing, modelling and interpretation procedures need to be carefully considered. This special issue illustrates and brings attention to why and how uncertainty handling (i.e. analysis, mitigation and communication) is a critical aspect within the geosciences. In this introductory paper, we (1) outline the terminology and describe the relationships between a number of descriptors often used to characterise and classify uncertainty and error, (2) present the collection of research papers that together form the special issue, the idea for which stems from a 2018 European Geosciences Union's General Assembly session entitled "Understanding the unknowns: recognition, quantification, influence and minimisation of uncertainty in the geosciences", and (3) discuss the limitations of the "traditional" treatment of uncertainty in the geosciences. "The efforts of many researchers have already cast much darkness on the subject, and it is likely that, if they continue, we will soon know nothing about it at all." – Mark Twain [ABSTRACT FROM AUTHOR]