Environmental Regimes in Asian Subregions: China and the Third Pole by Simon Marsden, is an excellent contribution to the scholarship on environmental regulation in Asia. The work is split into five chapters, with Chapters 2 to 4 providing insightful examples of environmental regimes in Southwest Asia, Central Asia, and Southeast Asia, respectively, while Chapter 5 focuses on linking South and East Asia through environmental governance of the Third Pole. To date there has been a lack of comparative exploration of environmental regimes in Asia's subregions and this work goes some way to remedying that. It helpfully provides contextualization of environmental agreements in their subregions, historically, politically, and environmentally, while also addressing how the environment of the Third Pole may be regulated in the future.

Through examination of select subregional regimes, Marsden determines that a focus on developing and establishing effective regulatory frameworks for diversity conservation and transboundary environmental impact assessments [EIA] is most likely to gain support in any future regime development for the Third Pole. He then goes on to define the Third Pole and explore the political constraints on subregional governance, particularly with reference to water management, biodiversity protection, and infrastructure development. The geographical definition of the Third Pole as being primarily constituted by the Himalayas and Tibetan Plateau, including the Hindu Kush Mountains, is supplemented by a discussion of its similarities and differences to the First and Second Poles, in particular significant population, climate, and richness of biodiversity differences. Interestingly, he does not discuss the environmental governance of the First and Second Poles, instead signalling that the differences mean that the existing regimes in Asian subregions are more relevant for comparison. A running theme through the work is the prominence of infrastructure development projects in Asian subregions and the role of international lenders, such as the Asian Infrastructure Development Bank and the Asian Development Bank, and Marsden emphasizes how they can play a role in ensuring the careful environmental management of the Third Pole through, for example, the continued inclusion of EIA requirements in lending agreements. He concludes the work by highlighting that, although the regimes in other Asian subregions have for the most part failed to make particularly positive contributions to environmental protection, they may nonetheless have institutional arrangements, objectives, principles, and provisions that are transferable or capable of transfer to the Third Pole. His recommendations include the development of a subregional environmental regime building on existing agreements in the Asian subregions, while ensuring that China is invited to participate fully, and collaboration between China, India, Pakistan, and the other states of the subregion is prioritized.

Although, at times in Chapters 2 to 4 the link between China and the Third Pole is not made effectively enough, leaving the reader to question the relevance of the very detailed examples, the examples given are underexplored in the existing literature and the contextualization provided in this book will help readers to understand the complexity of these subregional regimes and difficulties inherent in studying regionalism where regions themselves are hard to define.