To be sustainable, an economy can’t expand to a size that overwhelms the ecological capacity of the place it occupies. Given that the size of an economy is equal to its population multiplied by its per capita consumption, a sustainable economy requires stabilization of both factors. But that begs the question: stabilization at what level? Just how many people (consuming how much stuff) can any given place accommodate? No political entity has seemed willing to ask this question or step up to the challenge of finding an answer… until now.

With the release of the report What is an Optimum/Sustainable Population for Vermont?, Vermont has become the first state in the U.S. to determine its sustainable population size. The report was published by Vermonters for a Sustainable Population, an environmental organization that is concerned about the adverse impacts of unsustainable population growth, even in the second most rural state in the nation. It breaks new ground by both presenting estimates of a sustainable population and setting an example for other political entities to follow.

“Sustainable” is a word that is often used in these challenging environmental times, but rarely is it used in the context of population size and growth. The report carefully defines a sustainable human population as:

…one where the people living in a given politically or geographically defined area (such as Vermont) do not live beyond the limits of the renewable resources of that area for either input (energy and matter) or output (food, material goods, and absorption of pollution). They then purchase or trade from environmentally-aware sources those necessities that cannot be locally satisfied, either in sufficient amounts or at all. They will thereby be living in a manner that present and future generations of people, and all other life native to that area, will be able to enjoy a healthy habitat over the long term.

This definition is different from others in that it says a specific geographic area has to be defined, all life (not just human) has to be considered, and what can’t be produced within the region must be purchased from environmentally responsible sources.

VSP_ReportThe report uses a “whole systems thinking” approach with fifteen different indicators to calculate sustainable population size. The indicators are biodiversity, democracy, ecological footprint, environmental health, greenhouse gas emissions, food self-sufficiency, forest cover, happiness, quality of life, renewable energy, rural living/working landscape, scenic beauty, spiritual connectedness, steady state economy, and water quality.

Vermont’s current population is approximately 626,000. The analyses conducted for fourteen of the fifteen indicators produced estimates of sustainable population. The estimates range from 150,000 for the ecological footprint indicator to 700,000 for the quality of life indicator. The average of all fifteen indicators is approximately 500,000. Eric Zencey, a fellow of the Gund Institute for Ecological Economics at the University of Vermont, ran the analysis for the steady state indicator and projected a sustainable population of 600,000. The steady state indicator (along with the ecological footprint) is one of the most important indicators in the report because moving toward a steady state economy will have a positive influence on all the other indicators.

The write-up for each indicator in the seventy-page report contains definitions, a statement on the importance to Vermonters, current trends, an analysis of the effects of continuing population growth, and a projection of sustainable population size, not to mention plenty of graphics and photos. According to Lisa Sammet, President of Vermonters for a Sustainable Population, “In terms of the future health of Vermont’s environment and its overall quality of life, this is probably the most important report ever released. The sixteen experts who wrote the indicators are among the most knowledgeable people in Vermont for their field, and their writing is important for everyone who cares about the future of Vermont.”

The report is gaining national and international attention. Robert Walker, the President of the Population Institute in Washington, DC, says, “Discussions about what constitutes an optimal, sustainable population will always elicit varying opinions, but it’s a discussion that is well worth having. People everywhere, including Vermont, need to have a better understanding of how population pressures are affecting natural resources, living conditions, biodiversity, and the bio-systems that sustain human well-being. This is an informative and eye-opening report.” Reviews from local, state, national, and international experts, including Robert Costanza, the former director of the Gund Institute, are included in the report.

Perhaps the most important thing the report accomplishes is opening the door to a discussion that has been absent from the public discourse. Vermonters are now starting a serious conversation about how many people the state can sustainably support — it’s not only the mountains that make Vermont the “Green” Mountain State.

George Plumb is the executive director of Vermonters for a Sustainable Population and a longtime supporter of the steady state economy.