In this study, metrics of biodiversity, consumption, and pollution show extremely strong correlations when charted against human population size and its per capita impacts. We describe causal mechanisms for these correlations. Then, using available data, we show that slowing and gradually reversing population growth to ∼4 billion or less by 2200, while moderating per capita impacts, is the path toward sustainability. Among the benefits are habitat recovery and conservation of wild species, reduced greenhouse gas emissions and other pollutants, reduced conflict over resources, and the reduction of global poverty.
Shorter: All the world’s problems solved by getting rid of humanity. I will simply note that the lead author of this inanity, Mark Keegan, is affiliated with Columbia University Teachers College. Others are listed as working in “Urban Environment and Human Resources,” Philosophy, and the Department of Population Sciences.
Granted, these “experts” insist that this shift should be non-coercive and driven by education, women’s opportunities, and contraception access.
Instead, they believe it could largely be achieved by giving women family planning services and improving girls’ educational opportunities, especially in low-income countries where these privileges remain out of reach for many.
This isn’t necessarily a new argument, and there is some data to back this argument up. Once Iran started efforts to promote family planning, the fertility rate (the number of children each woman has) dropped from 4.08 in 1992 to 1.94 in 2001. In South Korea, it fell from 4.07 in 1972 to 1.93 in 1984. For Costa Rica, the decline was slower, but the trend remained the same, falling from 4.16 in 1972 to 1.98 in 2009.
None of this was achieved through coercive or manipulative means. It was achieved by improving reproductive health services and broadening education for girls.
“When women are free to decide how many children to have, fertility rates tend to fall toward replacement level or below, often rapidly,” the study authors write.
In other words, it presents population decline not as a warning sign but as a deliberately chosen path to a “pro-human” and pro-nature future, using a long-range projection to make that outcome seem both inevitable and desirable.
I would argue that we need fewer “experts” like this, and more engineers and inventors who will make it easier for humans to have as many children as we want by creating the tools and technologies that would allow more people to live in harmony with this planet…and the others we will be heading to in the near future.
I am very sorry to say I bought into this argument early on in my life. Fortunately, I had the opportunity to have a child and build a family. However, how many young, impressionable minds are being exposed to these charts, graphs, and pseudointellectual arguments, and making decisions that will lead to a childless future that, ultimately, they learn is devoid of joy and meaning?
Personally, I am heartened by the very strong response to this piece in social media.
A new study argues that cutting Earth’s population to 4 billion is the best way to secure a ”pro-human,” sustainable future.
Published in the journal Sustainable Development, the paper, co-authored by Mark Keegan and an international team of researchers, argues that accelerating… pic.twitter.com/rDKBdg2Znv
— Shining Science (@ShiningScience) August 2, 2026
What is presented as neutral analysis is, in reality, a value-laden prescription that narrows the scope of acceptable solutions to one deeply consequential path.
A truly sustainable future should prioritize innovation, resilience, and human prosperity alongside environmental stewardship. “Trusted Science” should not treat humanity itself as a variable to be reduced.
If the goal is a livable planet, the answer lies in expanding our capacity to thrive within it, not shrinking the number of people allowed to try.
(UKR)