On the complexity of model complexity: Viewpoints across the geosciences

It is the core task of geoscientists to gain insight into the complex systems of nature. Yet, complexity may be perceived very differently and a plethora of models with different degrees of complexity is available. How do we, geoscientists, decide what model complexity is warranted? Does this differ among disciplines? And, how do we even define model complexity? We developed a short questionnaire to investigate the geoscientific community's views on complexity in models. The response was overwhelming, with 618 completed responses. The results show that the number of processes explicitly included and the number of interactions / feedbacks incorporated were seen as important determinants of complexity. Confidence was not per se higher in the simulations of a complex model compared to a simple one. Interestingly, neither gender, the discipline within the geosciences, nor career stage or work sector, explained the characterization of model complexity. The results of the questionnaire demonstrate that there is no general consensus on how model complexity is perceived or should be defined, and that formal definitions are not broadly or generally accepted. In an environment seeking greater collaboration and interdisciplinarity, these results indicate the need for conscious dialogue about this topic among different model users.