Environmental law became global through the adoption of environmental treaties in the last quarter decade of the 20th century. Similarly, globalisation of criminal law accelerated when the Convention on Transnational Organised Crime 2000 (CTOC) deepened international legal cooperation between States to combat transnational crime. A protocol to the CTOC, complemented by voluntary guidelines and model legislation, could promote international harmonisation of laws against environmental crimes. This article argues that the time is right to bring together certain elements of international environmental and transnational criminal law.