Does humanity’s growing use of materials mean that decoupling is impossible? In a word, no, and attempts to reduce all resource and environmental problems to our material footprint won’t help us solve problems of resource scarcity or environmental impacts.
In a recent article for Fast Company, the University of London’s Jason Hickel claims that humanity can only consume 50 billion tons of “stuff” each year (compared to current consumption levels at about 80 billion tons). And according to several papers that Hickel cites, that can’t be achieved in the foreseeable future, given growing populations and economies. The only solution, according to Hickel, is to ditch our addiction to GDP growth.
Hickel is challenging the concept of “green growth,” which he describes as “absolute decoupling of GDP from material use.” But before talking about evidence for or against decoupling, it's important to ask: decoupling of what?
Broadly, there are two reasons to worry about consumption: running out of materials (like fossil fuels) and environmental impacts (like pollution or habitat loss). These often get conflated in unhelpful ways. What Hickel refers to when he talks about decoupling is material flows, which are dominated by things like fossil fuels, metal ores, construction minerals, biomass, and the like.
Lumping different material flows together can be misleading, in that it groups together resources that are being used sustainably with those that aren’t, and/or resources that cause big environmental impacts with those that cause smaller environmental impacts. So let’s look at the materials at play here.
For several of the materials with the biggest footprint in terms of volume (construction minerals, metal ores, etc.), the problem isn’t really that we're at risk of running out of stuff. Construction minerals account for a large portion of global material flows, but those are resources like stone — last time I checked, we weren't approaching peak stone. (Cue joke about the end of the Stone Age.) We could have a perfectly sustainable civilization without absolutely decoupling from stone for a long time. The 50 billion tons limit is completely arbitrary — it was based on material consumption in the year 2000 — and shouldn’t be taken as the dividing line between sustainability and environmental doom.
What about environmental impacts? Here, too, aggregate resource consumption can give a misleading picture. Some of the big items in material flows (again, like construction minerals) account for a pretty small portion of environmental impacts like greenhouse emissions or land use. For biomass, we've managed to increase production and thus mass flows a lot using the same amount of land, so the impacts haven't gone up in proportion to the mass flows.
When we look at the actual impacts — like greenhouse emissions, habitat loss, pollution of air and water, and so on — we're seeing some positive trends, and in fact some instances of absolute decoupling. Emissions of several pollutants (like sulfur dioxide) have peaked and declined globally, although they are still going up in some developing nations; nitrogen oxides and nitrous oxide emissions are flat globally. Total farmland area (the most important driver of biodiversity and habitat loss and an important driver of carbon emissions) has peaked, although it's plausible that it will go up again. Water extraction peaked several decades ago in the United States, in spite of increasing industrial and agricultural output.
Greenhouse emissions have not peaked globally, and may continue to go up for a while, making carbon emissions perhaps the least decoupled and most concerning of all trends. Even relative decoupling has come to a halt as coal-heavy China accounts for an increasing share of global emissions. As Breakthrough has written about for a long time now, we are still a long way from scalable food and energy systems that run without fossil fuels. But here, too, the most pragmatic solutions involve accelerating technological substitution of clean energy for dirty energy — the same general process of decoupling that has driven progress in other resources.
Some or most of these trends may be moving too slowly for Hickel and other observers, and indeed, where acceleration is possible, that should be both the technological and policy goal. But aggregate human consumption of resources doesn’t tell us much of interest about either resource sustainability or environmental impacts. To get at those problems, we need to look at things resource by resource, pollutant by pollutant. And when we do that, we see some significant progress, along with some still-worrying trends.
Above all, though, we know that as societies develop, food and energy production gets more resource-efficient, economic growth slows down, and fertility rates decline. All of these trends still imply large environmental impacts in the future. But while intentional economic degrowth or hard limits on resource use seem far-fetched, absolute decoupling of the things that matter — environmental impacts — is still a very real possibility.