Mexico contributes approximately 1 per cent of international GHG emissions, mainly from the burning of fossil fuels for transportation and power generation. The country is considered highly vulnerable to climate change; around 70 per cent of the national population will be affected by its effects. With 11,000 kilometres of coastline Mexico is on the most frequent path of tropical storms. Within the framework of Mexican federalism, the General Law on Climate Change of Mexico distributes planning, implementation, and evaluation responsibilities among federal, state, and municipal authorities, while maintaining a centralised point of view in the design of climate policy and the definition of national strategy. The federal government defines national policy and leads international negotiations. Climate action in states and municipalities varies greatly; it is subject to adequate political will, governance and funding. The state of Yucatán has advanced a regional and state strategy to achieve climate goals, has engaged neighbouring states and municipalities to address climate vulnerability, and is participating in international mitigation and adaptation initiatives. It is an example to other states for its commitment to a more resilient future. For other states to do the same, a systematic and inclusive approach is needed at the national level to effectively implement Mexico’s nationally determined contributions. Coordination mechanisms exist, but still need to be exploited to their full potential to improve Mexico’s capacity to generate clear and tangible results on climate action.

This chapter outlines the significance and urgency of the current global water crisis and demonstrates that the existing international legal architecture for transboundary freshwater ecosystems requires significant improvement to meet current and predicted transboundary water challenges, resolve conflict and strengthen cooperation. The chapter sets out the three overarching objectives of the book. First, to understand the rising impact of regional approaches to international law on transboundary freshwater ecosystems. This includes identifying the contribution of the UNECE Water Convention and other relevant UNECE environmental instruments as a coherent legal regime. Second, to provide a more coherent understanding of the relationship between the UNECE environmental regime, international water law, international environmental law and general international law. This includes examining the contribution of the UNECE regime to cornerstone rules and principles of international water law and emerging or missing concepts such an ecosystem approach or public participation. Third, to understand how the UNECE regime adds to or interacts (on a normative and an institutional level) with river basin agreements, river basin commissions, European Union water law and national law. The introduction highlights the timely nature of the enquiry against the contemporary context and frames the book’s place against existing writing on this subject.

This chapter lays out a novel framework for conceptualising the water-relevant binding and non-binding instruments of the UNECE environmental conventions as one common normative regional environmental regime – an original contribution. In exploring the idea of a single regime, this chapter seeks to overcome a strictly positivist view of international law and understand the relevance of overlapping and/or non-uniform state membership of the UNECE legal instruments. It explores regionalism and regional approaches to international law and examines the relationship of the UNECE regime to international law and other international institutions. It sets out a framework for determining the UNECE regime’s relationship to general international law and other international water treaties – asking whether the regime lex specialis – a theme returned to throughout the remainder of the book. This chapter sets out a framework for exploring the making, implementation and enforcement of international law in the UNECE regime, which is employed throughout the research. This frame contributes to understanding around systemic integration, mutually supportive interpretation and cross-fertilisation in international environmental law and international law relevant to transboundary freshwater ecosystems.