By Professor Robert Giegengack, University of Pennsylvania
“Sustainability”, as widely used in environmental and economic dialogue, does not describe a condition likely to be achieved in the near future, if ever.
Before the modern era of environmental wordsmithing, a “sustainable system” was one that could continue to function indefinitely without depleting the resources on which it depended.
Many natural systems are understood to be sustainable to the extent that they have persisted for many years, indeed for millions or hundreds of millions of years. Systems that were not sustainable have not persisted, and thus are not available for inspection.
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Resource economists of various stripes have suggested that certain artificially constrained systems could be described as “sustainable” if they yielded predictable products from year to year without diminution of the resource base that provided that productivity. Thus, individual commercial fisheries have been described as “sustainable” if the annual yield of harvested fish was replenished within a year and thus would allow a similar harvest the following year, and in subsequent years. The lobster fishery in the Gulf of Maine is now described as “sustainable” because the annual harvest has been stable for years.
However, the concept of a “sustainable fishery” ignores the resources that are used in maintenance of the fishery and in collecting the harvest. The primary resource so used is, of course, the energy that is required to drive the boats, collect and process the product, and regulate the performance of participants in the fishery. All of those activities use energy, most of it derived from combustion of fossil hydrocarbons, which, in our outrageous hubris, we choose to call “fossil fuels”.
Gifford Pinchot, the son of a wealthy NY importer and real-estate speculator, studied “sustainable forestry” in France in 1899-1900, and returned to endow, with his father, the Yale School of Forestry (now Forestry and Environmental Studies). Pinchot was well connected in Washington, and by 1905 had become the Director of what eventually became the US Forest Service, with administrative authority over millions of acres of forest and grasslands across the USA. From his training in France, Pinchot advocated “the art of producing from the forest whatever it can yield for the service of man.” To Pinchot, the national forests were to be used for commercial benefit, but in a way that would not diminish the value of the resource through that exploitation. Pinchot did not use the term “sustainable”, but he imagined that the yield of forest products would not exceed the rate of regrowth. Pinchot’s environmental ethic placed him at odds with the preservationists of his era, who hoped that the national forests would be preserved for public enjoyment rather than exploited for commercial gain. No doubt Pinchot was influenced by the management of European forests, all of which had been managed for so many generations that, effectively, no undisturbed forest survives in Europe.
The US National Forests continue to be exploited for commercial gain, but the judgment of the sustainability of that gain does not include the energy cost or administrative cost of maintaining the infrastructure that allows exploitation of forest products. Today, the US Forest Service spends ten times as much money maintaining logging roads into the interior of the national forests as royalties from the extraction of forest products yields. That is not “sustainable”.
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We know that the coal, oil, and natural gas that now power much of modern civilization accumulated over the 550 million years of Phanerozoic history. As far as we know, no fossil hydrocarbons that we identify today accumulated prior to that time.
We began extracting and burning fossil hydrocarbons on a commercial scale in the middle of the 18th century. While many projections have been offered of the expected lifetime of the fossil-fuel industry, no reliable estimate has suggested that there will be any extractable fossil fuel after 2300 AD. Thus, we will have used up the global supply of fossil fuel in 550 years, or ONE MILLION TIMES faster than that resource is being replenished.
As long as we operate in an industrial economy dependent on fossil hydrocarbons as an energy source, NOTHING THAT WE ARE DOING IS SUSTAINABLE!
What we seek in a “sustainable” system is a system in which all resources would be extracted at rates that would not exceed the rate at which those resources are being replenished (by natural processes).
We can imagine an industrial society in which all required energy comes directly from the Sun (that is how human society operated prior to ~1750). While that energy is not “sustainable”, since it is derived from the fusion of elemental hydrogen within the Sun, we know with some confidence that the solar fusion reactor will continue to operate for several billion years before the hydrogen that drives the fusion reaction is fully depleted. To the human time frame, several billion years is essentially forever, so we can think of direct Solar energy as inexhaustible, and systems that depend on that energy source (most systems on the surface of Earth) as potentially sustainable.
The Sun delivers an average of 342 watts/m2 to the Earth’s surface. That is 8,500 TIMES the amount of energy currently used by all of human civilization.
However, there are consequences to our use of Solar energy as a fully renewable resource. We will use that resource to extract the other resources we need (metallic and non-metallic ores, food, etc.), and many of the resources we routinely extract are not being replenished at the rate at which we extract those resources. Some of the metallic ores on which we depend are not being replenished at all; they accumulated under geochemical conditions that prevailed earlier in Earth history and are not represented anywhere on Earth today. Thus, even if we are able to convert our industrial society to one driven entirely by direct Solar energy, we will still need to extract other resources at rates that greatly exceed the rates at which they are being replenished. That will not be “sustainable”.
So, comprehensive recycling of key resources must be achieved along with conversion of human society to full dependence on direct Solar energy. Recycling of products that have been dispersed by patterns of human use will require vast amounts of energy, but in a Solar-powered world vast amounts of energy will be available. That recycling will be most efficient if recycling strategies can be built into the industries that today use those key resources (in this context, the work of Scott Cassell’s Product Stewardship Institute is a clear example of a pathway to a future that is less unsustainable than the pathway we are on).
And there is another problem: The industrial systems that we now use to provide human civilization with the products it demands generate huge amounts of waste. Today, that waste is being dumped into natural reservoirs (air, water, soil, etc.) at rates that greatly exceed the capacity of those reservoirs to neutralize or assimilate those wastes. We are contaminating the reservoirs of the renewable resources on which we depend (water, air, soil nutrients, etc.).
So, a human society that imagines itself as moving toward a sustainable configuration will also have to recycle products that today we consider waste, and to keep those products from contaminating other resources on which we depend.
[Some futurists have offered the possibility of capturing and processing asteroids that stray into the near vicinity of Earth. A single iron-nickel asteroid 1 km in diameter would provide as much of those 2 metals as civilization has used to date. The challenges of harvesting those resources and delivering them to Earth are, of course, daunting, but not beyond imagination, especially with an inexhaustible supply of Solar energy.]
In 2006, Penn’s President Amy Gutmann signed the “President’s Climate Commitment”, in which she pledged Penn to review its resource use comprehensively, and to undertake to reduce the University’s “carbon footprint” substantially, maybe even to zero (!!). In response to that announcement, Stan Laskowski (one of my EES colleagues and former Deputy Regional Administrator of EPA Region 3 for 20+ years) designed a course entitled “Sustainability at Penn”. He asked me to “co-teach” that course with him.
I agreed to do so if Stan would agree to change the title to “Toward Sustainability at Penn”. Stan and I taught the course, ENVS 494, for 2 years, and then I taught it with Dan Garofalo (Director of Sustainability at FRES) for another 2 years. Now Dan teaches the course himself…
That course allowed (or forced) me to explore the concept of “sustainability” very critically, with a group of smart, committed, principled, idealistic young people. I think we agreed that absolute sustainability is not an achievable goal, for Penn or for any other institution. We decided that the goal of our course would be to help Penn become less unsustainable. Perhaps we should redefine the concept…
So, here is my “redefinition” of “sustainability”:
Sustainability is a state in which humankind:
- extracts natural resources at rates that do not exceed the human capacity to discover replacement and/or substitute resources;
- re-uses those resources as much as possible; and
- disposes of the ultimate waste products of that activity at rates that do not exceed the capacity of natural systems to assimilate and neutralize those wastes.
The State of Sustainability can be achieved when Humankind devises a humane and globally equitable strategy to maintain the human population at a level at which efficient and frugal use of natural resources allows conditions 1-3 to be met.
Others have addressed this issue, of course. In 1990, Herman Daly, one of the early students of sustainable natural systems, offered this definition:
[sustainability will be achieved when:]
- For renewable resources, the rate of harvest should not exceed the rate of regeneration (sustainable yield);
- [For pollution] The rates of waste generation from projects should not exceed the assimilative capacity of the environment (sustainable waste disposal); and
- For nonrenewable resources the depletion of the nonrenewable resources should require comparable development of renewable substitutes for that resource.
I did not read Daly until long after we had offered ENVS 494. He reached basically the same conclusions, long ago. Daly did not say, specifically, that sustainability is unachievable. I think it is unachievable.
Of course, I prefer not to use the term “sustainability” at all. It belongs with that litany of environmental buzz-words that we use so carelessly, not because we define them precisely, but because they make us feel good:
Natural, organic, pure, pristine, artisanal, chemical-free, hormone-free, antibiotic-free, non-GMO, anti-oxidant, local, Omega-3, pomegranate (?) – the list goes on and on, ad nauseum.
Words matter. Sustainability is not a useful word. Sorry (!)