Citation: Earth Matters 46–47 2000 a magazine published by the Earth Institute at Columbia University, Winter 1999/2000. This issue contains many of the speeches that were presented at the "State of The Planet" conference held at Columbia in the Fall of 1999.
Keywords: natural resources
Areas of Research: Technology & Human Environment
With most animal populations, the niches that encase the populations are of constant size. Animal societies growing in a given niche have dynamics neatly fitted by equations with a constant limit or ceiling. In short, from a niche point of view, resources are the limits to numbers. But access to resources depends on technologies. When the animals can invent new technologies, such as when bacteria produce a new enzyme to dismantle a sleepy component of their broth, then we face a problem. New growth pulses suddenly pop up, growing from the prior.
Homo faber, the toolmaker, keeps inventing all the time, so that our limits are fleeting. These moving edges confound forecasting the long-run size of humanity. Expansion of the niche, the accessing and redefinition of resources, keeps happening with humans.
One of the greatest technological shifts was the industrial revolution. If we take the “industrial revolution” as one huge innovation, we can reconceive the population history of England and other countries in two phases.
The early English, islanders conceptually similar to the bacteria in a petri dish, could not directly expand their territory to support more people. In fact, by Roman times the English had already cleared a large fraction of their land for crops and animal husbandry. English population shows a slow rise, leveling around 5 million people in the year 1650. Perhaps sensing their local limit, the English were actively colonizing abroad during the 17th and 18th centuries and exporting population. The Island population remained rather level until nearly 1800. But meanwhile, another pulse of 50 million had begun, bringing England to its current population. Faster and cheaper transport, new energy sources, and other features of the industrial revolution made it possible for more English to eat in the same dish.
The growth of human populations demonstrates the elasticity of the human niche, determined largely by technology. For the homo faber, the limits to numbers keep shifting, in the English case by a factor of 10 in less than two centuries.
Now let me briefly scan two resources about which we worry, farmland and forests. Is farmland finite in any useful sense? For centuries, farmers expanded cropland faster than population grew, and thus cropland per person rose. When we needed more food, we ploughed more land, and fears about running out of arable land grew. But fifty years ago, farmers stopped plowing up more nature per capita. Meanwhile, growth in calories in the world’s food supply has continued to outpace population, especially in poor countries. Per hectare, farmers lifted world grain yields about 2 percent annually since 1960. Two percent sounds small but compounds to large effects: it doubles in 35 years and quadruples in 70.
Vast frontiers for even more agricultural improvement remain open. On the same area, the average world farmer grows only about 20% of the corn or beans of the top Iowa farmer, and the average Iowa farmer lags more than 30 years behind the yields of his most productive neighbor. Top producers now grow more than 20 tons of corn per hectare compared with a world average for all crops of about 2. From one hectare, an American farmer in 1900 could provide calories or protein for a year for 3 people. In 1999 the top farmers can feed 80 people for a year from the same area. So farmland again abounds, disappointing sellers who get cheap prices per hectare almost everywhere.
Forests tell a similar tale. Forests are cut to clear land for farms and settlements and also for fuel, lumber, and pulp. In the rich countries, nevertheless, forests have re-grown in recent decades. Since 1950 the volume of wood on American timberland has grown 30%, while European forests have similarly increased in volume. In the US, the intensity of use of wood defined as the wood product consumed per dollar of GDP has declined about 2.5% annually since 1900. Today an average American consumes about half the timber for all uses as a counterpart in 1900.
In the US, likely continuing fall in intensity of use of forest products should more than counter the effects of growing population and affluence, leading to an average annual decline in the amount of timber harvested for products. A conservative annual improvement in forest growth would compound the benefits of falling demand. Unmanaged forests now yield yearly an average of 1-2 cubic meters of commercially valuable species per hectare. Potential in secondary temperate forests ranges between 5 and 10 cubic meters. Many commercial plantation forests now reliably produce more than 20 cubic meters year, and experimental plots have yielded over 60 cubic meters. Compounded, the rising tree growth and falling wood demand should shrink the extent of US logging by half in 50 years.
By the middle of the 21st century, rising productivity of well-managed forests should comfortably allow 20% or less of today’s forest area of about 3 billion hectares to supply world commercial wood demand. In fact, 5% of world forests could suffice. Our vision of Earth’s surface in the year 2050 should be more forest cover, say 200 million hectares more than today, and most of the world’s forests reserved for Nature.
Knowledge, not more cropland or more timberland, is what now grows productivity, and science and engineering are the most powerful forms of knowledge. They demonstrate their effectiveness every moment. Wisely used, science and technology can liberate the environment, can spare the Earth. Food and fiber decoupled from acreage as well as carbon–free hydrogen energy and closed–loop industrial ecosystems can assuage fears about vanishing species, changing climate, and poisoning metals. And about finite resources. The greatest threat to future well–being is the rejection of science. Having come this far, the 6 billion cannot take the road back. Without science, the elastic band will snap back.
Exploring, inventive humanity exemplifies the lifting of carrying capacity. Through the invention and diffusion of technology, humans alter and expand their niche, redefine resources, and violate population forecasts. In the 1920’s, the leading demographer, Raymond Pearl, estimated the globe could support two billion people, while today about six billion dwell here. Today, many Earth observers seem stuck in their mental petri dishes. The resources around us are elastic.