Environmental philosophy professor at Colorado State University, Phil Cafaro, and Pernilla Hansson and Frank Götmark of the University of Göteborg published the full paper "Overpopulation is a major cause of biodiversity loss and smaller human populations are necessary to preserve what is left" - from which this abstract is taken - in the journal Biological Conservation here in August, 2022. We also reprint, above, part of a rebuttal by Aalayna Green and colleagues which followed in the journal.
Global biodiversity decline is best understood as too many people consuming and producing too much and displacing other species. Wild landscapes and seascapes are replaced with people, our domestics and commensals, our economic support systems, and our trash. Conservation biologists have documented many of the ways that human activity drives global biodiversity loss, but they generally neglect the role of overpopulation. We summarize the evidence for how excessive human numbers destroy and degrade habitats for other species, and how population decrease opens possibilities for ecological restoration. We discuss opportunities for further research into how human demographic changes help or hinder conservation efforts. Finally, we encourage conservation biologists to advocate for smaller populations, through improved access to modern contraception and explicit promotion of small families. In the long term, smaller human populations are necessary to preserve biodiversity in both less developed and more developed parts of the world. Whether the goal is to save threatened species, create more protected areas, restore degraded landscapes, limit climate disruption, or any of the other objectives key to preserving biodiversity, reducing the size of the human population is necessary to achieve it.
You can read the rest of this paper in Biological Conservation: https://www.sciencedirect.com/science/article/abs/pii/S0006320722001999