The 1969 UN Report “Problems of the Human Environment” was a seminal work that first highlighted environmental problems at a global scale. This report underpinned a series of subsequent international summits and conventions of the 1992 Rio Earth Summit and the subsequent three global conventions on Biodiversity, Climate Change and Desertification. We assessed the report half a century after its publication to track changes in vocabulary and highlight critical lessons that could have been learned. The assessment contains several strengths and weaknesses that are pertinent to modern global-scale analyses. Many issues of that day have declined in importance or been superseded, and several major environmental problems (including climate change and plastic pollution) were not foreseen. Most of the report’s predictions proved to be much more conservative than proved by reality (a criticism that has also been levelled at contemporary IPCC reports). The report, however, did forewarn of global pandemics and stimulated thinking on a global scale that led to identification of the current climate crisis.