Climate Action is one of the United Nation’s Sustainable Development Goals. Yet, despite calls for action, global governments have broadly not taken consequential change to reduce carbon outputs and mitigate warming. Our chapter argues that a primary cause of this inaction is political conflict and policy capacity. Without strong economic incentives and facing constrained resources, governments may opt to proceed with the status quo. Here, health systems present a critical resource to engage nations in climate action. Health systems produce political leverage as major political stakeholders across nations, globally, for engaging in broader climate policy and a wealth of resources inherent to health systems – expertise, funding – to directly implement climate policy. The case study of the city of Toronto in Canada offers lessons for directly involving health systems in subnational climate action as policy stakeholders and implementors, and the co-benefits health system engagement brings to promote climate action intersectorally. Toronto provides an important case for high-latitude countries that will soon be facing climate hazards tropical nations have been grappling with for centuries. Engaging health systems in climate action policy processes may improve the likelihood of success for strengthening resilience and adaptivity to climate related hazards.