Climate modelling is growing in importance in disputes, such as investor state disputes concerned with climate attribution. Dr Alex Lee, Chartered Geologist and Scientist, head of the environmental and climate change team at HKA, explains how climate modelling works and sets out his experience involving, for example, nuclear waste, power stations in coastal locations, and groundwater contamination. He also sets out the complexities of such models and the need for standardisation. He considers the role and importance of the precautionary principle, particularly in conditions of uncertainty.