The Coffin in the Room: Catastrophic Impacts on Human Population

The Future of Humanity, Part 5

Photo by WantTo Create on Unsplash.

This is the fifth — and most distressing — post in my 7-part series on the future of humanity. The series starts here.

Climate projections versus population projections

There is a puzzling disconnect at the core of climate science between climate projections and population projections. Indeed, comparing the two, one might be forgiven for thinking that population scientists and climate scientists live in two completely different worlds.

On the one hand, climate scientists foretell a world of unprecedented disasters over the next decades and centuries: deadly heat, floods, droughts, mega-storms, abandoned coastlines, freshwater scarcity, food shortages, etc., etc. But on the other hand, population scientists at the UN are projecting a world population that continues to grow, largely driven by high birth rates in poorer countries (those most vulnerable to climate change impacts). In a report released in 2019, UN scientists projected that world population would rise from 7.9 billion today to 9.7 billion by 2050, before leveling off at nearly 11 billion around 2100 (source).

The disconnect between these two visions of humanity’s future is dizzying. To take one example, the UN estimates that the population of sub-Saharan Africa will double by 2050. Yet the latest climate warnings from the IPCC tell us that a 2°C hotter world by 2050 is both likely and likely to devastate sub-Saharan Africa, producing droughts, floods, food shortages, and regional warming so deadly that outdoor work may become impossible for much of the year in much of the region (source). How can anyone expect population to double in such circumstances?

The answer has to do with how the IPCC climate models are constructed.

The climate models used in the IPCC reports only include population as an input variable, not as an output variable. They predict climate changes based (in part) on a given level of population (usually taken from those UN projections), but they do not…