Four letters and one equation sit at the center of Colcom Foundation’s environmental philosophy. The equation, I = P x A x T, was developed by environmental scientists Paul Ehrlich and John Holdren. It states that environmental impact (I) equals population size (P) multiplied by per capita affluence or consumption (A) multiplied by the efficiency of technology (T).
Three Variables, One Outcome
A recently updated page on the Colcom Foundation website explains why the organization treats all three inputs as essential. Its reasoning is straightforward. If consumption falls and technology improves while population keeps rising, the total environmental gain is limited. Each person may tread more lightly, yet the combined footprint can still grow.
Biocapacity offers another example. The country used 227 percent of its available biocapacity in 1970 and roughly 240 percent in 2020, while per capita use fell by more than 20 percent. In the Foundation’s reading, the rise in overshoot stems entirely from more people sharing the same land and water.
The Foundation turns to the U.S. record for evidence. Between 1970 and 2021, per capita carbon dioxide emissions dropped from 21.33 to 14.04 metric tons, a 35 percent decline. Over the same years, the population climbed from 205 million to 332 million. National emissions rose 15 percent overall. The page says the same pattern shows up in biocapacity consumption, urban land conversion, and wildlife decline.
Research Cited by the Foundation
Colcom Foundation also leans on peer-reviewed literature. It highlights a 2022 study in Biological Conservation by Cafaro and colleagues, which concluded that population growth is a fundamental driver of biodiversity loss and that population decrease facilitates ecological restoration. The Foundation says it funds public education that communicates this body of research to wider audiences.
The Pittsburgh nonprofit traces its start to 1996, when the late Cordelia S. May set it up. Beyond its national education work, it backs conservation, environmental projects, and cultural assets across southwestern Pennsylvania, giving the equation a local dimension as well. Read this article for additional information.
More about Colcom Foundation on https://waterlandlife.org/land-conservation/colcom-revolving-fund-for-local-land-trusts/