Welcome! I'm a philosophy professor at Colorado State University living in Fort Collins, Colorado with my wife Kris. My scholarly work centers on environmental ethics, population policy and the preservation of wild nature. I'm the author of Thoreau's Living Ethics: Walden and the Pursuit of Virtue and How Many Is Too Many? The Progressive Argument for Reducing Immigration into the United States. I am an affiliated faculty member of CSU’s School of Global Environmental Sustainability and past president of the International Society for Environmental Ethics.

For the past six years, Swedish ecologist Frank Götmark, Australian agronomist Jane O'Sullivan and I have been co-principle investigators for The Overpopulation Project, headquartered at the University of Gothenburg, Sweden. With help from the GAIA Earth–Balance Foundation, we have been studying the environmental impacts of overpopulation and advocating humane policies to reduce human numbers and preserve biodiversity. Our recent publications include:

* Population Effects on Biodiversity and Climate Change: Evidence from Recent Scientific Literature, 2010-2022. P. Cafaro, P. Hansson and F. Götmark. Indian Journal of Population and Development 3 (2023): 149-206. 

* Procreation and Consumption in the Real World. P. Cafaro. Environmental Ethics 45 (2023): 295-306.

* An analysis of three decades of increasing carbon emissions: The weight of the P factor. L. Tamburino, P. Cafaro and G. Bravo. Sustainability (2023) 15: 3245.

* Overpopulation is a major cause of biodiversity loss and smaller human populations are necessary to preserve what is left. P. Cafaro, P. Hansson and F. Götmark. Biological Conservation 272 (2022): 109646.

* Reducing human numbers and the size of our economies is necessary to avoid a mass extinction and share Earth justly with other species. P. Cafaro. Philosophia 50 (2022): in press.

* Climate change and world population. J. O'Sullivan. In T. Letcher (ed.), The Impacts of Climate Change: A Comprehensive Study of Physical, Biophysical, Social, and Political Issues (Elsevier, 2021): 313-350.

* Discussing Population Concepts: Overpopulation is a Necessary Word and an Inconvenient Truth. F. Götmark, J. O’Sullivan and P. Cafaro. Indian Journal of Population and Development 1 (2021): 51-60.

* Climate Ethics and Population Policy: A Review of Recent Philosophical Work. P. Cafaro. WIRES: Climate Change 12 (2021): e748 (1-17).

* Just Population Policies for an Overpopulated World. P. Cafaro. Ecological Citizen 5 (2021): epub-046-1 (1-10).

Complete CV