Regional economic integration organizations (REIOs) can ratify climate change agreements as mixed agreements, including the Paris Agreement, with their member states. A question may arise on what responsibilities can REIOs have under the Paris Agreement in relation to the member states. Analyzing the draft articles on the responsibility of international organizations reveals that REIO can have derived (indirect) responsibility for non-fulfilling the obligations by member states due to the normative control resulting from the adoption of binding resolutions. Also, under Article 4.18 of the Paris Agreement, REIO will be jointly responsible for non-realization of the goals communicated in the NDCs together with non-compliant member. This will make the non-compliant states responsible externally to the third parties and to REIO internally in achieving the goals of NDC and will encourage the compliant member states to participate in realizing the collective goal of REIO because of influence of not realizing the collective goal.

I. Introduction
II. REIOs in Mixed Agreements
III. Responsibility of REIO under DARIO
    A. Direct Responsibility of REIO
    B. Indirect or Derived Responsibility of REIO
IV. Responsibility of REIO under the PA
    A. The Exclusive Responsibility of REIO
    B. The Joint Responsibility of REIO
    C. Different Scenarios of Responsibility for REIO and Its MemberStates
V. Conclusion

• Hojjat Salimi Turkamani(Associate Professor of International Law at Azarbaijan Shahid Madani University, Tabriz, Iran, International Fellow, Alexander von Humboldt Foundation at Heidelberg University. LL.M., Ph.D. (Allameh Tabataba’i U., Iran))