We very much acknowledge the work from United Nations Department of Economic and Social Affairs (UN DESA) on the latest „World Population Prospects 2024“ (World Population Prospects 2024: Summary of Results) report (population.un.org), one of the flag ship reports from UN DESA and certainly one of the crucial reports to support global political decision making and global governance. It projects a global total population development peak of ca. 10,3 billion in the mid-2080s, and then the global population will return to around 10,2 billion by the end of the century (see graph).
John Wilmoth, Director, Population Division (UN DESA), being asked during the report presentation press conference about how climate change (we would asked about “global warming, climate change, and the loss of biodiversity”) is reflected in the report: „… we don’t really have a good way of taking that into account … I would say at this point no one really has the answer on how to incorporate concerns about climate change into our projections …“. (cf. “UN Department of Economic and Social Affairs (UN DESA) on the World Population Prospects 2024: Summary of Results – Press Briefing”, 11 Jul 2024, minute 28:08 till 30:15, https://webtv.un.org/en/asset/k1p/k1ppqf57ll)
Global warming, climate change, and the loss of biodiversity is also or first of all a science crises
We developed out of several sources a scenario about global warming and the correlated total global population. So, we did a first rough draft, you also might call it a (heuristic) “theory”, on how global warming, climate change, and the loss of biodiversity looks like from a trans- & interdisciplinary perspective (see graph).
We included the UN „World Population Prospects 2024“ report projection. The scenario then shows a rising gap between our total global population projection (“expected global population”) and the projection form UN DESA (“UN „World Population Prospects 2024“ report projection”) to up to ca. 6 billion people by the end of the century. This assumes a “average global temperature rise” of ca. 5°C till the end of the century.
As much as we question boarders between people, we also question disciplines within science. Data, mathematics, and statistics is not the end of science, it is the start or the fundament for the development of (trans- & interdisciplinary) scientific theories. A projection about the development of the total global population without taking into account the findings from e.g. the “Intergovernmental Panel on Climate Change (IPCC)” is in our view a “scientific catastrophe”. Global warming, climate change, and the loss of biodiversity is in our view the most dangerous development for humanity ever in history. To support differentiated global governance, to support insightful political decision making, and to support a first global referendum on climate actions, we need (trans- & interdisciplinary) scenarios on the development of global population.
One of the basic tasks from science is in our view to support sophisticated political decision making. We urgently pledge for a revised upcoming UN „World Population Prospects 2025“ report, explicitly including the IPCC gobal warming scenarios.