Integrated Assessment Models (IAMs) are pivotal tools that synthesize knowledge from climate science, economics, and policy to evaluate the interactions between human activities and the climate system. They serve as essential instruments for policymakers, providing insights into the potential outcomes of various climate policies and strategies. Given the complexity and inherent uncertainties in both the climate system and socio-economic processes, understanding and effectively managing uncertainty within IAMs is crucial for robust climate policy development. This review aims to provide a comprehensive overview of how IAMs handle uncertainty, highlighting recent methodological advancements and their implications for climate policy. I examine the types of uncertainties present in IAMs, discuss various modeling approaches to address these uncertainties, and explore recent developments in the field, including the incorporation of advanced computational methods.