While the regulation of sustainable growth and CO2 emissions has become a transnational legal affair, the legal-theoretical implications of the climate emergency remain relatively under-researched. On the one hand, recent jurisprudence in human rights law has seen an increased sensibility for identifying environmental aspects of human rights, constitutional rights to environmental goods enshrined in half the world’s statesas well as a new trend towards identifying an autonomous environmental human right. On the other hand, constitutional scholars have articulated detailed accounts of how transnational legal pluralism is to be properly understood and managed as globalization and trade-liberalization create collective action spaces, observably regulated by constitutional principles, such as the rule of law, democracy and human rights. In this paper, I first survey the shortcomings of the principles of environmental law (Section 1) and discuss the nature and possibility of autonomous environmental rights (Section 2). Then, I disentangle competing conceptions of constitutional pluralism (Section 3), and argue for a legal realist conception of transnational law that can better deal with the climate emergency (Section 4).