In this article we discuss two phases in the evolution of global environmental programs, namely the Man and Biosphere Programme and the International Geosphere-Biosphere Programme, with the aim of showing their hidden diplomatic ambitions from both US and Soviet perspectives. In the 1960s and 1970s, Soviet views on the biosphere prevailed thanks to the influence of Soviet scientists in the International Council of Scientific Unions and the United Nations Educational, Scientific and Cultural Organization. In the 1980s, the domination of this field by US scientists ushered in the establishment of Earth system science as a new research trend based on Earth observation technologies. We argue that despite the influence of Soviet ecologists in directing international coordination of research on the biosphere, Earth system science did not set in a trajectory of environmental cooperation. This outcome can be explained if we take the environmental and ecological turn that arose during the Cold War as being intertwined with political concerns and national interests in both the US and the USSR. Security, scientific diplomacy, and geopolitical issues limited East-West collaboration on the interdisciplinary study of the earth, which instead turned into a sort of cooperative antagonism. The transition from biosphere studies to Earth system science reveals a changing strategy toward environmental problems, which in turn reflects changes in Cold War policy. This essay is part of a special issue entitled Science Diplomacy , edited by Giulia Rispoli and Simone Turchetti.