Abstract A reader examining a contemporary account of international environmental law 20, 30 or 50 years from now may be interested not only in its accuracy but also in what the account conveys of our own generational perception of our past. By then, several features will have become evident to that reader, which our generation missed or under-estimated. One above all is likely to connect our and their perception of what international environmental law had to face: humanity, through its production and consumption processes, is changing not only human history but also the dynamics of the entire Earth System in what some see as a new geological epoch defined by humans, the ‘Anthropocene’. This major fact is and will remain with us, and the extent to which it can be addressed depends on whether we see it and integrate it in our policies. This article argues that such is not the case of the social practice we call international environmental law, and this is, above all, for a very specific reason: international environmental law is built around an asymmetry between the legal organization of production and consumption processes – the ‘transaction’ – and the regulation of their side effects or ‘negative externalities’. At the core of international environmental law lies a deliberate effort to preserve legal space for the transaction – the very processes that led us into the Anthropocene – while aiming to minimize its negative side effects for the global environment. It is an odd mismatch, akin to a legal requirement to keep the dam gates open while also requiring that the flooded areas be kept as dry as possible. International environmental law is faced with impacts affecting the geological timescale, but it is structured to preserve the cause of the problem and focus on side effects unfolding in a human timescale.