Sustainability and food researchers Joseph Poore, Hannah Ritchie and Charles Godfray look at places where shrinking farmland has freed up land for nature – and ask how far the trend could go. Throughout the 20th Century, humanity demanded more and more land leading to the loss of vast areas of natural forest and grassland. Today, around half the world’s land is farmed, used to grow crops or graze animals. However, according to the UN’s Food and Agriculture Organization (FAO), global agricultural land use peaked in the early 2000s and has been slowly falling ever since. Around the world, farmland is being replaced by grasslands, trees and bush. Wild animals are returning to abandoned pasturelands in areas they had once dominated. Reaching “peak agricultural land” does not mean the problem of deforestation is solved. Growing demand for products like beef, soy, cocoa and palm oil has put increasing pressure on land across South America, South East Asia and Africa. In the last decade, the world lost an area of tropical forest twice the size of Spain. Still, acre-for-acre across the world there has been yet more farmland abandonment, driven by reforestation in Europe and North America and the abandonment of pastures in Australia and Central Asia. here are a few different reasons for this. Firstly, farming has become more efficient. The use of improved seeds, fertilisers, pesticides and irrigation has in recent decades vastly increased how productive the land we farm is, doubling, tripling and even quadrupling yields depending on the crop and country. Since 1961, FAO data shows that productivity increases have spared 1.8 billion hectares (4.4 billion acres, or around 35 Spains) of land from being brought into cultivation. We’ve also squeezed more efficiency improvements in animal agriculture through intensive farming, productive animal strains and optimised feeding regimes. As these systems intensified, lower productivity lands have been abandoned in many countries. But it’s not all about intensification. We have also replaced some land-hungry crops with near-landless alternatives: wool and cotton have been to a major extent replaced by synthetic fibres; tobacco is rapidly being replaced by synthetic nicotine; flavourings in food such as vanilla are now largely synthetic; the global caffeine (although not coffee) market is dominated by production in labs; synthetic sweeteners have replaced substantial amounts of sugar cane and sugar beet. We estimate that these synthetic substitutes have spared over 110 million hectares (two Spains) of land from farming.

Grown using the Miyawaki method, fast-growing miniature forests in the middle of cities can bring surprisingly big benefits for people and the environment. “It’s like going on a bear hunt!” Not quite, perhaps, but these kids are definitely excited. They are on a visit to a miniscule patch of forest in the grounds of Queen Margaret University on the outskirts of Edinburgh, Scotland, and are about to head out armed with a bucket of water, a jug and a stopwatch. They are measuring how fast patches of soil inside and outside the forest absorb water, so we leave the small circular howff (a traditionally-built shelter with a wildflower roof) in the middle of the vegetation. The child in charge of the stopwatch does a couple of test runs and the pouring begins. “I want you to decide when it’s all gone,” says Elly Kinross, the woodland and greenspace officer at Edinburgh and Lothians Greenspace Trust who is running this session for the kids. “The grass can be wet, but basically the water needs to be gone… Yeh I think that’s gone. OK, good, give it a stop.”  This class of eight- and nine-year-olds is spending the day in a tiny forest (known, in Scotland, as a wee forest): small tennis court-sized patches of land, usually in urban areas, rigorously prepared and planted with the makings of a fast-growing, dense native forest.   These petite patches of greenery have been springing up across the world for decades now. Japan has planted thousands; India, where the tiny forest concept was developed, hundreds. The Netherlands is a hotspot for them too, and they are also now beginning to spring up across the US. But it is the UK that has most recently seen an enormous push towards these miniature urban forests, with hundreds planted since 2020. As I visit the site alongside these schoolchildren on a beautifully sunny spring day, I’m also on a kind of hunt. I’m trying to work out how big the benefits of foresting such tiny areas really are. As it turns out, I’ve stumbled onto a thorny, decades-long debate. A tiny revolution  In many countries, including my home country of Scotland, there is now a huge effort to try to reforest large areas of land. This tends to concentrate on large, unbroken patches of land, and with good reason: such forests are critical for protecting wildlife and human health and have enormous benefits for carbon storage and water cycling. But while smaller patches of forest have historically been somewhat dismissed as useful nature reserves, they do have benefits. One big plus is that they are easier to fit into an urban area – and thus be nearer to where most people live. And emerging evidence is showing we might have underestimated their benefits for nature too.