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This article appeared in the magazine Earth Matters, published by the
Earth Institute at
Columbia University. 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.
Citation: "Resources are Elastic," Earth Matters pp. 46-47, Winter 1999/2000.
URL http://phe.rockefeller.edu/EMwinter/
Resources are Elastic
Jesse H. Ausubel
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.
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