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This early tree is a warning about our unsustainable planetary growth

Scale trees – huge, hulking structures which may have helped bring about an ice age which then destroyed them – are an apt metaphor for the present-day myth of infinite growth on a finite planet, writes Sheffield Green peer Natalie Bennett.

Scale tree fossil

Fossilised bark of the prehistoric scale tree (Lepidodendron).

James St. John (Flickr)

Around 309 million years ago, in the Carboniferous age that stored the bulk of the coal we’ve over the recent centuries extracted at scale from the Earth, nature was still in the early stages of the development of trees.

Among those standing tall then were Lepidodenrons, also known as scale trees. They looked a little like a palm tree when mature, with the first five metres or so a single trunk covered in diamond-shaped scales, and for another five metres with a frond-like single leaf emerging from each scale. Not great, it seems, at catching light, although helped by the fact the scales also photosynthesised, not just the leaves.*

It was an early model, a model that stored vast amounts of carbon and pumped the Earth’s oxygen level up to 50% higher than today. But it’s not a model we see today. Other, more varied forms of tree generally grow slower but more surely. Because scale trees, while they had the first hard bark, were more like a soft shrub on the inside. They lacked resilience.

Scale trees are an apt metaphor for today’s rich nations, particularly the UK; where we consume our share of the resources of more than three planets while so many people struggle to put food on the table and keep a roof over their heads, where life expectancy in the poorest areas is stalled or falling, where basic infrastructure, from roads to schools, crumbles around us, where workers get sicker and bosses’ pay gets higher.

While most politicians are chasing after the chimera of growth that, like the scale trees reaching their peak, is no longer possible, they’re not seeking to shore up the trunks that support our society; the outsourced public services with their underpaid workers, the austerity-hit school system being loaded with more and more demands to support the young living in our unhealthy, poverty-stricken society.

They’re not addressing the problems of a broken food system, multinational companies profiting hugely from extracting commodities from farmers at minimum cost and turning them into ultraprocessed, plastic-wrapped pap to attract but not satisfy, deliver calories but not nutrition. They’re not looking at how a handful of companies like the great parasite Amazon collect profits and ship them offshore, while we all pay for the cost of their waste, their exploited workers and their destruction of local economies.

The focus is always on reaching higher, instead of reinforcing the structure of what we have for an inevitable age of shocks – from pandemics to climate instability to wars – created entirely by human activities.

Greens have long understood that you can’t have infinite growth on a finite planet. As the Stockholm Institute has been at the forefront of explaining, we’re now at or exceeding multiple physical limits of this fragile planet. The climate emergency and nature crisis are just two aspects of this. The pervasive pollution of our world with ‘novel entities’ like plastics, pharmaceuticals and pesticides is another recently identified.

We were talking about food security as a crucial issue long before the government was finally forced to acknowledge that we couldn’t just rely on supermarkets to feed us, as Boris Johnson suggested. We’ve focused on resilience as the crucial measure, rather than ‘efficiency’ – which is usually a euphamism for short-term low prices that ignore long-term costs.

Nature moved on from the scale tree to produce the sturdy oak, the fruitful chestnut, the graceful plane tree and many other varieties. But it wasn’t their competition that saw off the scale tree. The scale tree altered its own environment, grew so fast and voluminously that it eventually sucked so much carbon out of the atmosphere that it ushered in a near-ice age, accompanied by a great increase in aridity. Those were conditions in which the scale tree itself could not live.

Yes, the scale tree really is a very good model for the risks we’re running today – treating the planet as a mine and a dumping ground, instead of acknowledging that rather than having a bigger economy, we need one that share resources out fairly, so everyone has enough for a decent life, and the planet and its natural systems have a chance to head back towards some kind of balance.


* The opening description of the scale tree comes from Otherlands: A World in the Making by Thomas Halliday, one of the most brilliant books of 2022.

Learn more

You can support the publication of Natalie Bennett's upcoming book, Change Everything: Common Sense Politics for the Age of Shocks, via Unbound.

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