The rise of sub-national actors in global climate governance underscores the
need for clear alignment between these efforts and their national
counterparts. As these sub-national climate actions are filling gaps in
mitigation, adaptation, and financing, among other functions, a critical
question is how these efforts complement or overlap with national climate
pledges. This consideration is particularly important in the context of the
Paris Agreement’s mandate for fiveyear review cycles, where national
governments will be asked to demonstrate progress towards climate mitigation
goals and increase their ambition. In this paper, we argue that alignment –
both vertically between multiple jurisdictions and horizontally with external
networks and actors – is critical to clarifying climate actions between
multiple levels of actors and to maximizing mitigation potential. We use nine
case studies to demonstrate the varying degrees and modes of vertical
integration between subnational and national climate actors. We find that the
case studies embody different styles of vertical alignment, and exhibit
significant variation in the degree and direction of vertical alignment within
each of these modes. We also find that many case studies rely on horizontally-
aligned international networks and coalitions to fill gaps in financial
resources or technical support. As a proof of concept, we demonstrate that an
additional 1 gigaton carbon dioxide equivalent (CO2e) in 2020 can be achieved
in these nine case studies through stronger alignment that makes it possible
to scale sub-national climate actions to the national level. These findings
suggest there may be a missed opportunity to realize greater mitigation
potential by fostering stronger vertical alignment, and enhancing coordination
between horizontal networks of climate action and national governments
