Agent-based systems have become an important area of research since the 1990s. They have been applied to a range of domains that are intrinsically complex. Among these, environmental problems are of special concern, given their ample affectation to our societies and everyday quality of life. This report provides a review of agent-based systems applied to environmental problems of diverse nature. The usefulness of Multi-Agent Systems (MASs) to model complex systems that embed multiple and dynamic interactions, such as in environmental processes, is revealed.