"In theory GDP growth could continue indefinitely – if it weren't linked to something real."

William Rees, who along with Mathis Wackernagel developed Ecological Footprint analysis, commented on Paul Krugman's flippant slur on "degrowth" as an odd bedfellow of "the prophets of climate despair." The bottom line for Rees is that it is not really a choice between growth or degrowth but between planned, orderly degrowth or painful, chaotic degrowth imposed by nature. Growth in GDP could, "in theory," go on indefinitely ONLY if it wasn't linked to the biophysical world, which historically and currently it is. With permission, I reproduce Bill's comments below:

One might like to think that 'de-growth' is a non-issue – that somehow the human enterprise can continue to expand – but this is not a realistic proposition. De-growth will happen probably in the next few decades; the relevant question is ‘by what means?’ 

Here’s why: 

First, any analysis of this type should be based on available data, not mere assertion of preferences or beliefs. "Show me the numbers" is the first commandment of sustainability assessment. 

Second, we should clarify what we are talking about and what we are not talking about. Here I am not talking about increases/decreases in income or GDP per se. Income growth or GDP/growth per capita is a money measure with no physical dimensions. Money is mere abstraction – in fact, most money today is mere 'number money' or electronic money that exists only in computers and whether the number is $1 or $1,000,000,000 makes no difference to the planet whatsoever. In theory, then, GDP growth could continue indefinitely – if it weren't linked to something real. 

But it is linked to something real, the biophysical world. People buy real wealth (food, clothing, shelter, autos, electronic toys, etc.) with money wealth and there has never been a period when increases in money income were not accompanied by increases in real energy and material consumption. At higher income levels the relationship begins to level out because of greater ‘factor productivity’ (efficiency) and as more discretionary income goes to purchasing services (economists call this ‘decoupling’), but: a) decoupling is, so far, a marginal trend even in rich countries and; b) most of the world’s people have not nearly satisfied their material needs, let alone wants. Consequently, global material and energy throughput is generally increasing in both per capita and gross terms. Remember too that, from a biophysical perspective, all economic production is mostly consumption—a vastly larger quantity of available energy/matter is processed or consumed than is contained in the products produced (and the ratio is deteriorating because of diminishing returns)

And herein lies the problem. Energy and material production and consumption has material consequences for ecosystems that are vital for sustainability, i.e., survival. Consider just one fact: all food and fibre flows through the economy are produced by ecosystems and all the wastes of both our bio-metabolism and industrial metabolism must be assimilated and neutralized by ecosystems.

These are measurable processes with measurable consequences. Ecological footprint analysis shows that to produce the bio-resources consumed, and to assimilate just the carbon wastes of the average European requires about five hectares of ecosystems of global average productivity (5 gha). Typical North Americans use the ecological services of 7-8 gha/capita. Meanwhile, people in the most impoverished African countries get by on the life support of perhaps half a gha. (As I said, there is a clear positive relationship between income and the consumption of ‘nature’.) By the way, these are underestimates because we use the more optimistic data where there are conflicts between sources, not all material/waste flows are included and because we assume sustainable land and water use which it is not the case.

The problem is that there are only 12 to 13 billion hectares of land and water ecosystems productive enough to support economic activity on Earth. That’s about 1.7 gha per capita (at the present population of 7.2 billion). This means that Europeans are using three times and North Americans five times their ‘fair Earthshares’. Put another way, we’d need several more Earth-like planets to support just the present world population at European or North American material standards with current technologies. (Poor people don’t get nearly their fair Earthshare because they don’t have enough money to compete in the marketplace.)

Now, the average human ecological footprint is about 2.7 gha so even at today’s average levels of material consumption, the human enterprise is in overshoot by about 50%. This means humans are consuming faster than ecosystems can regenerate and producing waste faster than ecosystems can assimilate. (Climate change is driven, in part, by carbon dioxide emissions. CO2 is the largest waste by weight of industrial economies so, in this sense, climate change is a waste-management problem.) Economic growth and accompanying increases in energy and material consumption today are based, in part, on the depletion of so-called ‘natural capital’ and on filling waste sinks to over-flowing. The continuation and expansion of these trends will precipitate significant changes in, or even the collapse of biophysical systems, including the climate system. Dependent human economies and societies will not be far behind (this constitutes unplanned de-growth).

This is not fantasy. Eco-failure is already happening regionally and, without global agreements leading to major reductions in human energy and material demand (i.e., planned de-growth), will happen globally. Indeed, globalization and trade ensure that that the next collapse will be global—many densely populated high-income countries have long since overshot their domestic carrying capacities and would long ago have collapsed without access to the resources/sinks of less developed regions. Globalization blinds citizens of nations in overshoot to the perils of over-population and over-consumption, since it eliminates any direct ‘negative feedback’ from their having exceeded national limits. (Japan, for example, despite its recent economic stall, still uses 5-7 times its domestic biocapacity, so far with impunity.) Keep in mind that that, absent access to distant sources, the destructive over-exploitation of regional ecosystems contributed to the collapse of many previous civilizations on all continents from Sumer to the Maya.

Summary and bottom line:

Historic and contemporary evidence suggests that global de-growth (meaning significant reductions in aggregate and per capita energy and material consumption and in the human population) is inevitable. If it is imposed by nature, it could be painful and chaotic; but a planned contraction of the human enterprise (both population and per capita consumption) to a sustainable steady-state could be relatively smooth and orderly. The plan might require accelerated de-growth in high-income consumer countries to accommodate greater consumption in poor regions for the sake of greater material equality.

Which form of de-growth would you prefer?

Which is the more likely to occur?

PS: Eco-footprint analysis is based on real data from the most reliable sources available for ecosystems productivity and for national production, consumption, and material trade. Some people do not like the results of such analyses, particularly the documentation of over-shoot and the support this provides for the notion of biophysical limits to growth and the need for material de-growth. Fair enough, but those who reject the findings on these grounds have an obligation to provide an alternative explanation and solution. The questions are: How can the human enterprise, as a fully-contained, dependent growing sub-system of the finite non-growing ecosphere (tip o' the hat to Herman Daly), continue to expand indefinitely? Once in severe overshoot, is a sustainable recovery possible without significant material de-growth?