Understanding Climate Change through Modelling and Simulation: A Case for Verification, Validation and Accreditation

The challenges associated with understanding Climate Change (CC) and subsequent socio-technical solutions stem from the complexity and uncertainties inherent within the mechanisms, magnitudes and temporal nature of the environment. Modelling & Simulation (M&S) has flourished as an enabling technology providing insight into the intricacies of Climate Change as well as facilitating understanding regarding the social and ecological implications of these changes. In addition, M&S has been instrumental in influencing decision making across many domains. The application of M&S to garner understanding of complex environmental behaviour often predicates the requirement to integrate various models and simulations. High Level Architecture (HLA) is a software architecture for constructing distributed simulations. It facilitates interoperability among different simulations and simulation types and promotes reuse of simulation software modules making it a very attractive option for M&S applications such as that within the CC domain. As the impact of the application of M&S transcends the ´virtual world´, the danger of adverse effects of erroneous or unsuitable models or simulation results also increases. The application of Verification and Validation (V&V) of models and simulation results are intended to ensure that only correct and suitable models and simulation results are used. Although individual models may have been V&V, there integration within an HLA framework may result in a simulation behaviour that yields inaccurate results and thereby creates a condition such that decisions and actions would be based on invalid results. Under the auspices of the NATO Modelling and Simulation Group (NMSG) 19 and Simulation Interoperability Standards Organization (SISO) Product Development Group (PDG), a VV&A overlay for the HLA Federation Development and Execution Process (FEDEP) in accordance with IEEE 1516.3 has been developed. This paper- - presents the key concepts of this VV&A overlay. The results of this paper are far reaching in terms of how we conduct VV&A activities within an HLA environment thereby shaping engineering and policy decisions.