CLIMATE CONSTITUTIONALISM IN COMPARATIVE PERSPECTIVE: OPENNESS CLAUSES IN BRAZIL AND PORTUGAL POSTAUTHORITARIAN CONSTITUTIONS AND ITS APPLICATION TO CLIMATE CHANGE INTERNATIONAL AGREEMENTS

This study aims to contribute to the understanding of the legal elements set out at multiple levels related to the Federative Republic of Brazil and the Portuguese Republic to address the causes of and adapt to the impacts of climate change. The methodological approach is presented based on the theory of legal formants developed by Rodolfo Sacco, complemented by a qualitative content analysis of constitutional, legislative, and jurisprudential sources. As for the content of the thesis, the first chapter is intended to establish the conceptual, historical, and legal frameworks that are indispensable for understanding the intersection between climate change and constitutional law from a comparative perspective. The second chapter reconstructs the historical and political contexts that led to the promulgation of the post-authoritarian constitutions of Portugal (1976) and Brazil (1988). The third chapter is devoted to the emerging phenomenon of climate litigation, understood as a legal instrument of growing relevance for the application and interpretation of climate-related obligations. The fourth chapter returns to the constitutional dimension to examine the normative architecture of the incorporation of international law, with an emphasis on opening clauses and their position in the hierarchy of norms. Finally, the conclusion summarizes the main findings of the research, reaffirming the relevance of constitutional instruments in promoting climate governance. Of particular note are the convergences and divergences between Brazil and Portugal in terms of constitutional design, the reception of international norms, and judicial action. It emphasizes the importance of multilevel legal integration, judicial engagement, and constitutional interpretation as strategies for overcoming the implementation deficit of international climate law. Ultimately, it concludes that national constitutions, through their opening clauses and democratic legitimacy, constitute essential normative and institutional bridges between global commitments and domestic accountability. Given this trajectory, it has been verified that national constitutions play an extremely important role in consolidating protection for the integrity of the climate system. Given the maintenance of the Westphalian model, it is important to seek solutions that are appropriate to the reality presented. In this sense, it is possible to observe that international politics cannot present the results necessary to fulfill the objectives pursued by the UNFCCC. So, it is palpable to offer as a solution an older legal institution, tested and refined over centuries. The Constitution has elements capable of promoting an adequate response to the mechanisms and aligned with the objectives of the UNFCCC. The constitutional opening clauses can offer a refined institutional design to address local efforts to tackle climate change, making it possible to direct pressure to policymakers (President, Senators, and Representatives) and to monitor/demand legislative/political results in a way that is already familiar to civil society. This proposal finds its basis in the model of constitutional gravitation presented in the study. In this sense, the robust constitutionalization of international law, integrated into appropriate institutional and legal architecture, is seen as the horizon for the ideal fulfillment of state commitments and goals at the international level, where the climate agenda is debated exhaustively. In addition to state efforts, the fundamental role of doctrine in exercising paths and proposals to most efficiently address the challenge of the century is emphasized, with the variables of time and effectiveness of actions being extremely relevant.