ConservationBytes.com

A few weeks ago we published a paper that was in the works for a long time, so long in fact that one of my co-authors died before it was published online.

That co-author was none other than the legendary Paul Ehrlich of Stanford University, and of The Population Bomb fame (and infamy). More importantly, but often overlooked, Paul wrote more than 700 scientific articles and 30 books during his career.

Paul Ehrlich died on 13 March 2026 at the ripe old age of 93, exactly two weeks before our article appeared online. Paul had a good innings no doubt, but I wish he had survived long enough to see what might very well be his last co-authored paper.

I first met Paul back in the mid-2000s during a trip through San Francisco. I had organised to come chat with Professor Gretchen Daily at Stanford, and Paul came along for lunch. I remember vividly how we clicked almost immediately.

We clicked so well in fact, that we wrote a book together, co-authored several high-impact papers (e.g., ‘ghastly future‘), spent a month in Bellagio as Rockefeller Foundation writing residents, participated in various public and parliamentary presentations, and generally just got on like a house on fire. Paul and his wife Ann became like family, so much so that they were de facto grandparents to my daughter who grew up with them in near-annual contact.

This post isn’t about Paul per se, but I cannot ignore the profound influence Paul had on my career, my personality, and my life view. I miss him. I am therefore dedicating this paper and post to his memory. So long, and thanks for all the fish.

Back to the paper in question.

The paper (Global human population has surpassed Earth’s sustainable carrying capacity) has already been downloaded nearly 23,000 times since it was published less than a month ago. It has an Altmetric score of 543, and is currently the top-trending paper in Environmental Research Letters.

Nothing like writing about human population to get the punters engaged.

We show empirically that the Earth has already exceeded its ability to support the global human population sustainably, with dire implications for increasing pressure on food security, climate stability, and human wellbeing. However, slowing population growth and raising global awareness could still offer us some hope.

Our study shows that humans have pushed well beyond the planet’s long-term carrying capacity and that continued growth under current patterns of consumption will intensify environmental and social challenges for communities worldwide.