A number of high-profile economists – people like Carlota Perez and Michael Liebreich – have recently come out swinging in favor of “green growth” theory, trying to assuage mounting public concerns about the fact that climate change and ecological breakdown are being driven by capitalist growth.

What’s interesting about these interventions is that they explicitly pit themselves against their opposite – the idea of de-growth. Even just a year or two ago, de-growth wouldn’t have been part of the conversation. Once the province of ecological economists, it’s now gaining more mainstream attention as the evidence against growth mounts – and orthodox economists have no choice but to reckon with it.

But as they try to edge their way around certain prickly facts, their arguments get stranger and stranger.

Green growth theory relies on the assumption that GDP growth can be permanently and absolutely decoupled from resource use and emissions, and at a pace that’s fast enough to reverse ecological breakdown and keep us under 1.5 degrees, so that GDP can continue growing forever while environmental impacts decline.

There’s just one problem. There’s no evidence that this is feasible.

Let’s start with emissions. Fortunately, we know that GDP can be absolutely decoupled from emissions. The real question is whether we can decarbonize fast enough to stay under 1.5 degrees, without relying on fanciful negative emissions technologies. The answer, sadly, is no. If we carry on with growth as usual, we need to decarbonize at a rate of 11% per year. That’s more than five times faster than the historic rate of decarbonization and about three times faster than what scientists project is possible, even under highly optimistic conditions.

But let’s imagine, just for the sake of argument, that we manage to pull it off: we manage to shut down the fossil fuel industry and switch the whole planet’s energy infrastructure over to renewables, quickly, despite continuous economic expansion. Does this solve our problem? Are we on track for green growth forever?

Sadly not – because we still have another issue to deal with, namely, resource use. What are we going to do with all of our clean energy? The same stuff we were doing with fossil fuels: trawl the oceans for fish, raze forests for timber, strip mountains for minerals, clear land for cattle feed, etc. And we will do this more and more each year, because that’s what growth demands.

This brings us to the next conundrum - even more difficult than the first. Can we continue to grow GDP indefinitely while reducing resource use down to sustainable levels? Well, existing data are not very promising: there is no historical evidence for this, and all extant model-based projections have found that permanent absolute decoupling of GDP from resource use cannot be accomplished even with rapid rates of technological innovation and strong government intervention (references here).

But green growthers are not deterred. What if we shift to an economy based on services and knowledge, they ask?

First of all, such a shift is already accounted for in the models. But we don’t need the models to answer this question. Services have grown dramatically in recent decades, as a proportion of world GDP - and yet during this same period global material use has not only continued to rise, but has accelerated, outstripping the rate of GDP growth. In other words, there has been a recoupling, a rematerialization, despite a shift to services.

The same is true of high-income nations as a group – and this despite the increasing contribution that knowledge is said to make to GDP growth in these economies. Indeed, while high-income nations have the highest share of services and knowledge in terms of contribution to GDP, they also have the highest rates of resource consumption per capita. By far.

Why is this? Partly because services require resource-intensive inputs (think universities and hospitals and airports and hotels). Partly also because the income acquired from the service sector is used to purchase resource-intensive consumer goods (you might get your income from YouTube videos, but you use it to buy TVs and cars and beef). And partly because our “knowledge” is geared primarily toward technological development – finding ways of increasing productivity and efficiency, which is then leveraged to expand production.

Our existing trajectory toward knowledge and services isn’t yielding the results that green growthers predict. So why should the future be any different?