It was raining, and I see no reason to stand in the rain listening to someone telling me what I already know, but without the wisdom acquired through a longer perspective on time and humanity than a teenager could have.

The unsustainability of human life is not new, although recognising the problem is relatively modern. The story goes that it was first noticed by an eighteenth century clergyman who sat down with his parish registers to reflect on his past year’s ministry and noticed something odd. He had conducted more baptisms that year than funerals. He thought perhaps the villagers had done particularly well in survival that year and checked against previous years, expecting to see years which were the other way round, but there were none. In every year he and his predecessors had conducted more baptisms than funerals which implied more births than deaths. This made no sense to the clerical gentleman. After all everyone must be born and everyone must die, so every birth should be balanced by a subsequent death. Yet that was not what the record showed. If more people were born than died, the population must increase, and if the population increased the amount of land available for food production must at some point fall short of what was needed by the rising number of people.

The predicted disaster has not yet happened because improvements in agricultural efficiency in the last two hundred years have enabled us to accommodate the increasing demand and that has led some to believe they will always do so, but that’s very much an act of faith. Past performance, as statutory financial warnings make very clear, is no guide to what might happen in the future.

However, people do not, in practice, believe that. Tried and tested formulae are the way most of us order our investments and activities, and that is why many of us get caught out.

Ever since Homo Sapiens emerged some tens of thousands of years ago, our lifestyle, like that of most creatures, has been unsustainable. The difference between us and other species on this issue is our increased ability to adapt to our changing circumstances. Whereas most creatures take from nature until the level of their impact reduces their option for further expansion to nil and thereafter live in an uneasy balance between frustrated growth and early death through starvation or predation, probably permanently hungry and surviving on the edge of their ability to endure, human beings are remarkably adept at moving the boundaries which confine us.

So, the Paleolithic hunter-gatherer mode of life gave way to Neolithic agriculture. Hunting and gathering, which is as far as most animals can get, is limiting because the more one takes out of nature without giving back, the less is left to replenish itself and the increasing rarity of food limits numbers and prosperity. Hunter-gathering can only be sustained if the population remains small, and a population which grows too large will be punished with hunger until the weakened population falls back to a level nature can feed. The human response was to help nature out by planting crops and breeding animals specifically for us to eat, thus relieving nature of the responsibility to replace what we took.

This might be termed the first of the “green revolutions” which have enabled food production to keep pace with demand and the human population to grow enormously while also increasing the material standard of living of many within that populace. There have been others since and humanity has continued to grow. We have grown ever since we appeared and know no other way to live.

Yet this growth has not been without cost. If we inspect the areas of the world where agriculture began — Mesopotamia and the Middle East, North Africa, and Central Asia — we can see the result a few thousand years later. Mostly, those areas are now deserts; their forests gone, and with them their clouds and rain, their soil reduced to dust and sand which blows around in the wind; bare rock and sand and heat and dust. Salinity from irrigation and evaporation made the soil arid. The desert advanced and continues to advance, and humanity must retreat as the land loses its fertility. Such is the the land which once fed our growth.

Still, we do not learn. Since the Industrial Revolution we have built worldwide trading systems to plunder natural resources with ever-growing efficiency and ingenuity. We have dug out coal and drilled for oil to fuel our growing demand by returning to the atmosphere in a century or two carbon which was removed millions of years before we arrived when the world’s climate was much warmer and the creatures which lived in it were different from those we know today. Economists predict more growth and enthuse with confidence in human ability to circumvent our limitations and find a sustainable way to go on growing for the indefinite future. Yet this is little short of madness. How can we continue to grow? What sort of world would we live in? Will we finish up standing shoulder to shoulder as on a crowded train becuse that’s all the room we each have on our finite planet?

Already, various experts give us contrary messages about how to solve the problem. We should eschew synthetic materials in favour of natural ones. We should use more synthetic materials so nature is under less pressure to produce the natural ones. Last time I had to replace some trousers I made a point of seeking out cotton ones because I was concerned about polyester microfibres from my washing going into filter-feeding animals in the sea. Then I heard about the severe environmental impact of cotton growing and processing. Maybe we should wear polyester but filter the waste water to remove the microfibres, but then, what about those shed on land when the clothes are worn?

I recently heard that a popular make of electric car has such complex supply chains that it is responsible for as much carbon emission by the time it leaves the showroom as a typical petrol car when it goes to the scrapyard! I have no way of checking that, but it sounds plausible. Car manufacture must be an extremely energy-intensive business. After all, they’re made of steel, which has to be smelted and melted, rolled, pressed and welded before you even consider making the moving parts to go into it. How all that compares with the environmental impact of the fuel which is burnt during use, again I have no idea. It seems obvious to me that the main inefficiency of a car is the need to move around a ton of metal to transport people weighing less than a tenth of that. Using a more lightweight material would be far more likely to reduce emissions than anything else, both in manufacture and use.

Any sensible person would surely conclude that sustainable lifestyle cannot be achieved by making a few consumer choices. The complexity of the world’s economy and the human desire to improve our material conditions creates irresistible pressure on the environment, and a radical change in our expectations is needed if we’re to make a difference. Previous generations took it for granted the Pyramids and the Taj Mahal existed without thinking they needed to see them with their own eyes. They took holidays in Scarborough or Eastbourne. They worked eight hour days and went home to their homes and gardens where their real lives were located. The economy might have been smaller, but people were happier and less pressured than they are now. Of course, the population was smaller, and much of the country’s wealth was built by the suffering of people elsewhere in the world, conveniently out of sight to the British public who knew little of what really went on in the colonies. Was that better? Maybe not.

However, if we’re not to mess the world up we do need a slower, less GDP-centred view of it, and so, of course, does everyone else. Setting an example of a better, slower way of life might be the best we can do, but can it be enough?