Since their emergence, Environmental Justice Movements have become increasingly influential in national and international governance systems. Their leaders claim they create bridges between civil society and institutions – either international organizations, nation states or local governments – thereby enhancing public deliberation. This claim had drawn some political theorists’ attention, contending these grassroots movements have a remarkable cognitive potential which includes playing an avant-garde role by integrating and redefining political concepts. Since climate change has become established as the preeminent environmental issue, these movements have evolved into climate justice movements and have begun to pose new challenges to national and international governance systems and institutions. Do contributions made by both waves fit the cognitive requirements to think properly about an ecological era shaped by humans? By applying the Anthropocene framework, my claim is they do not. After analyzing two key concepts endorsed by these movements - global justice and environmental sustainability – I argue they should not be considered preeminent theoretical agents as their defenders argue. That is because they lack an open and dynamic conception of sustainability, as well as enough awareness of outcomes’ uncertainty in their conception of international justice.