In emergency domain, specialists must make complex decisions to solve problems. Complex decisions are characterized as a complex dynamic system composed of interrelated variables. Complex decisions are made up of actions, and their complexity arises from the surrounding environment, including the context and the behaviors of the individuals involved. It is difficult to isolate the elements that influence such a decision. These decisions lead to unpredictable impacts, causing the need to deal with impacts mitigation in the earlier phases of the decision process and the emergency management cycle. To reach a consensus and solve complex decision problems, collaborative strategies are being used. The general knowledge and different experiences, acquired from the experts through collaborative approaches, is crucial to identify and discuss the impacts (consequences) of decisions actions in a broader way. This paper presents ImpactMap approach, a collaborative environment that allows exchange of ideas and perspectives to discuss and project impacts of complex decisions. This research was evaluated in an emergency simulation and the results achieved showed that this research approach is able to create an interactive environment and supports the impact projection needs of a decision team.