The process of international climate change law is increasingly emphasizing the role of non-state actors. Particularly, the Paris Agreement adopted a novel model compared to the Kyoto Protocol, moving away from mandatory emission reduction requirements towards procedures and mechanisms that encourage parties to voluntarily propose and enhance their climate targets, facilitating synergistic policy adjustments. This shift is widely regarded as a transition from a “regulatory” to a “catalytic and facilitative” model, representing an innovative response to the challenges faced by the Kyoto Protocol and the failure of the Copenhagen climate negotiations. Against this backdrop, the role of sub-national and non-state actors in international climate action has become increasingly prominent.