The increasing human pressures on the environment were already being studied by scientists in the first decades of the twentieth century. The diversity and extent of the unintended consequences of accelerating economic and technological development have rapidly grown since the middle of the previous century. As soon as these globalizing and complex processes were realized, the advancement of multidisciplinary international research cooperation proved crucial for their proper analysis, deriving precise assessments, and formulating science-based recommendations. This was made possible by the availability of sufficiently detailed and accurate observational data and the fact that some effects of the above-mentioned global processes reached clearly identifiable critical levels after a few decades. As concerns specific environmental components and problems collaboration has generally evolved within the framework of different environment-related scientific disciplines. This has included establishing various international organizations (institutions, unions, and associations), holding scientific conferences, launching research programs, and issuing assessments (reports, outlooks, etc.). In addition, institutional, inter- and multidisciplinary links have facilitated joint research and ‘synthesizing’ activities in some fields (e.g., as occurred within the interdisciplinary committees of the ICSU). The evolution of such international cooperation in environmental science is presented below for some globalizing problem areas. Regarding a number of other environmental issues, cooperation and its institutionalization developed in a more or less similar manner with corresponding stages but was obviously different in substance (e.g., concerning ozone-layer depletion, natural disasters and their effects, and the environmental/biogeochemical cycles of nitrogen and phosphorus1).