The interaction between GATT/WTO and legal regimes to combat climate change has experienced four important stages. First, both were created independently as two selfcontained legal regimes. Second, these regimes may potentially conflict with each other because climate change measures may violate the GATT/WTO rules. Third, if policies and measures are tailored well, the GATT/WTO and climate change legal regimes could be implemented simultaneously. Last, a shift to low carbon economy presses for close cooperation and mutual supportiveness between these two legal regimes. However, the multinational nature of these two legal regimes often delay or hamper global consensus on agenda for cooperation. This article argues that trade agreements as a regional approach have merits and advantages of pursuing harmonization and cooperation under the GATT/ WTO framework. Regional trade agreements can provide opportunities for a group of countries with concrete commitments and rules to cope with climate change beyond the possibility of the multilateral arena.

1. Introduction
2. The Linkages between the GATT/WTO and Climate Change Rules
    A. Free Trade, the Environment and Climate Change
    B. GATT/WTO and Climate Change Legal Regimes
    C. Attitude Shift: Towards Low-Carbon Economy
    D. Moving Forward: Regional Trade Agreements as Laboratories
3. Different ‘Ethos’ between Regional Trade Agreements and the GATT/WTO
    A. The History: Not a Rib from the GATT/WTO
    B. The Norm: Having Different Rules from the GATT/WTO
    C. The Demand: Regional Trade Agreements Needed
4. Tackling Climate Change: From Regional Trade Agreements to the GATT/WTO
    A. Environment and Climate Change Regulations in Present Regional Trade Agreements
    B. New Regional Trade Agreements to Combat Climate Change
    C. The Trans-Pacific Partnership as an Example
5. Conclusion
References

• Tsung-Sheng Liao(International Law at National Chung Cheng University, U. Wisconsin-Madison)