Since the second half of the 20th century, the International Council of Scientific Unions (ICSU) has sponsored international initiatives to investigate the Earth as a physical, chemical and biological system put in danger by human activities. In this context, a prominent collaboration emerged in the 1980s involving geophysicists from the US and the USSR to address the impact of humans on earth’s climate. This collaboration led to the Nuclear Winter theory, according to which a thermonuclear conflict could cool down the Earth’s temperature to such an extent to alter the biological processes as well as the geological components of the planet. In 1982, the ICSU established a Committee for the Assessment of the Environmental Consequences of Nuclear War under SCOPE’s supervision. The Commission was called to report on the effects of the nuclear warfare on the biosphere, however, in 1985, climate modelling for the NW started to be criticised by the US authorities being subjected to extensive smear campaigns interfering with SCOPE scientific findings. This paper explores the work of the ICSU in supporting research for the protection of the planetary environment, at the same time, mediating with growing political pressures pointing out the needs for incrementing security strategies and nuclear state expansion. This examination allows us to explore the network of interests and limitations underlying environmental cooperation that are notoriously geopolitical and military. Furthermore, it allows to evaluate what kind of scientific internationalism informed the role of SCOPE, which shaped research on the Earth-system modelling in Cold War times.
