Constructing a Material Century
he intensive use of materials in this century has deep
historical roots. Since the Industrial Revolution，
advances in technology and changes in society and in busi-
ness practices have interacted to build economies that could
extract， process， consume， and dispose of tremendous quan-
tities of materials. Although the roots of these trends extend
back centuries， most have matured only in the last 100
years.~~
The case of iron， the emblematic material of the Indus-
trial Revolution， illustrates how technological advances fed
materials use. In 1879， a British clerk and his chemist cousin
invented a process for making high-quality steel--a harder
and more durable alloy of iron--from any grade of iron ore，
eliminating the need for phosphorus-free ore. This innova-
tion cut steelmaking costs by some 80-90 percent which in
turn drove demand skyward: between 1870 and 1913， iron
ore production in Britain， Germany， and France multiplied
83-fold. Further innovations and robust demand led to a six-
fold increase in world production between 1913 and 1995.
Today， iron and steel account for 85 percent of world metals，
and a tenth， by weight， of world materials production.\"
As richer ores were depleted， new extractive technolo-
gies made it possible to mine metal from relatively poor
lodes， a practice known as \"low-grading.\" In 1900， it was not
feasible to extract copper， for example， from ore that con-
tained less than 3 percent of the metal. But technological
advances have since lowered the extraction threshold to less
than 0.S percent， increasing the number of sites where min-
ing is viable， and greatly expanding the quantity of ore
needed to extract the same amount of copper. As world cop-
per ploduction grew 22-fold over the century， in step with
rising demand for automotive and electrical uses， waste pro-
dLtction grew 73-fold. Likewise， modern logging and mining
equipment have made it possible to reduce tracts of forest
into sawn lumber in a matter of hours， or to shear off entire
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