Since their inception, climate change negotiations have stalled because of the scope of parties’ mitigation responsibilities under the United Nations Framework Convention on Climate Change (UNFCCC). The concept of common but differentiated responsibilities and respective capabilities (CBDR-RC) became a core principle of the framework to ensure consensus on a global climate policy in 1992 and to promote differentiation. By letting each country assess its current responsibilities and capacities for climate mitigation through their nationally determined contributions (NDCs), the Paris Agreement has built on the principle of CBDR-RC and promoted self-differentiation. As the concept evolved, the role of emerging economies has been a particular focus of discussions. Academia is still grappling with the revised meaning of CBDR-RC and the newly introduced NDCs. This article contributes to the discussion by analyzing the role of emerging economies in climate governance through the lens of regional responsibility. In particular, it discusses how cooperation can be a more effective way to ensure differentiation, especially by distinguishing emerging economies from other developing countries with fewer capacities. The article uses the Amazon rainforest as a case study, discussing Brazil’s role within the region. Building on lessons from regional schemes that have successfully promoted climate mitigation, the article looks at the Amazon Cooperation Treaty Organization (ACTO) as an avenue for enhanced cooperation at the regional level.