Human-environment systems are unpredictable and characterized by various irreversibilities that make reversing a course of action difficult if not impossible. These uncertainties and irreversibilities can come from both ecological and economic sources and identifying these sources can provide insight into current manage actions (or inactions) as well as the value of natural and social science information. This talk will illustrate how the combination of uncertainty and irreversibility influence optimal management of human-environment systems. The talk will start with an explanation of key concepts from decision theory that influence decision-making at the uncertainty-irreversibility nexus. It will then proceed to specific examples from invasive species and climate change.