PITY THE POOR MALTHUSIANS:

Perhaps one of the least fashionable predictions I made nine years ago was that 'the ecological footprint of human activity is probably shrinking' and 'we are getting more sustainable, not less, in the way we use the planet'. That is to say: our population and economy would grow, but we'd learn how to reduce what we take from the planet. And so it has proved. An MIT scientist, Andrew McAfee, recently documented this in a book called More from Less, showing how some nations are beginning to use less stuff: less metal, less water, less land. Not just in proportion to productivity: less stuff overall.

This does not quite fit with what the Extinction Rebellion lot are telling us. But the next time you hear Sir David Attenborough say: 'Anyone who thinks that you can have infinite growth on a planet with finite resources is either a madman or an economist', ask him this: 'But what if economic growth means using less stuff, not more?' For example, a normal drink can today contains 13 grams of aluminium, much of it recycled. In 1959, it contained 85 grams. Substituting the former for the latter is a contribution to economic growth, but it reduces the resources consumed per drink.

As for Britain, our consumption of 'stuff' probably peaked around the turn of the century -- an achievement that has gone almost entirely unnoticed. But the evidence is there. In 2011 Chris Goodall, an investor in electric vehicles, published research showing that the UK was now using not just relatively less 'stuff' every year, but absolutely less. Events have since vindicated his thesis. The quantity of all resources consumed per person in Britain (domestic extraction of biomass, metals, minerals and fossil fuels, plus imports minus exports) fell by a third between 2000 and 2017, from 12.5 tonnes to 8.5 tonnes. That's a faster decline than the increase in the number of people, so it means fewer resources consumed overall.

If this doesn't seem to make sense, then think about your own home. Mobile phones have the computing power of room-sized computers of the 1970s. I use mine instead of a camera, radio, torch, compass, map, calendar, watch, CD player, newspaper and pack of cards. LED light bulbs consume about a quarter as much electricity as incandescent bulbs for the same light. Modern buildings generally contain less steel and more of it is recycled. Offices are not yet paperless, but they use much less paper.

Even in cases when the use of stuff is not falling, it is rising more slowly than expected. For instance, experts in the 1970s forecast how much water the world would consume in the year 2000. In fact, the total usage that year was half as much as predicted. Not because there were fewer humans, but because human inventiveness allowed more efficient irrigation for agriculture, the biggest user of water.

Until recently, most economists assumed that these improvements were almost always in vain, because of rebound effects: if you cut the cost of something, people would just use more of it. Make lights less energy-hungry and people leave them on for longer. This is known as the Jevons paradox, after the 19th-century economist William Stanley Jevons, who first described it. But Andrew McAfee argues that the Jevons paradox doesn't hold up. Suppose you switch from incandescent to LED bulbs in your house and save about three-quarters of your electricity bill for lighting. You might leave more lights on for longer, but surely not four times as long.

Efficiencies in agriculture mean the world is now approaching 'peak farmland' -- despite the growing number of people and their demand for more and better food, the productivity of agriculture is rising so fast that human needs can be supplied by a shrinking amount of land. In 2012, Jesse Ausubel of Rockefeller University and his colleagues argued that, thanks to modern technology, we use 65 per cent less land to produce a given quantity of food compared with 50 years ago. By 2050, it's estimated that an area the size of India will have been released from the plough and the cow.

Land-sparing is the reason that forests are expanding, especially in rich countries. In 2006 Ausubel worked out that no reasonably wealthy country had a falling stock of forest, in terms of both tree density and acreage. Large animals are returning in abundance in rich countries; populations of wolves, deer, beavers, lynx, seals, sea eagles and bald eagles are all increasing; and now even tiger numbers are slowly climbing.

Perhaps the most surprising statistic is that Britain is using steadily less energy.

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