In the face of the current proliferation of existential threats-the risk of nuclear war, anthropogenic climate change, COVID-19, and (arguably) disruptive technologies like artificial intelligence-it is imperative that Australia embrace the notion of shared responsibility in international politics. Individual states have limited capacities to effectively tackle such large-scale, complex emergencies on their own. Highlighting the moral implications of the philosophical notion of joint action, this commentary makes the case for a particular type of responsibility, which can only be discharged when states deliberate and coordinate their actions. Moreover, it explores what this notion of shared responsibility means for Australia-and its international relationships-with respect to responding to climate chaos and COVID-19. Even though Australia, acting on its own, can neither significantly mitigate climate change nor halt the current global pandemic, it nevertheless has demanding moral responsibilities to respond to both. This is because the capacities necessary to affect meaningful change can be created through collaboration with other institutional agents. In the absence of intergovernmental organizations able to respond effectively to such crises, Australia has shared responsibilities to contribute to establishing, and then acting as part of, informal, purpose-driven, climate change and COVID-19 ‘coalitions of the obligated’.