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Do consumers’ behavior and producers’ efficiency
move in consistent patterns?
Paul E Waggoner and Jesse H. Ausubel
The Connecticut Agricultural Experiment Station, New Haven and
Rockefeller University, New York.
October 2002
A population may have more or less income to spend and spend more or less of it on
objects. Producers may affect the environment more or less as they make the objects. In
quantities and with balanced dimensions, the identity ImPACT* connects the actors’ to
environmental impact, showing the leverage each can exert.
I = P  A  C  T where
I or Im = environmental impact,
P = population,
A = income, as GDP per person,
C = consumers’ behavior, as product use per GDP, and
T = producers’ efficiency, as impact per product.
Sometimes C is called intensity of use, A affluence and T technology. We call falling C
dematerialization.
Despite ImPACT’s implication of independence among variables on the right, an
income elasticity of (b-1) connects C to A, a relation which we explored in an earlier paper.*
In this supplement on line, we explore whether another pair of variables, C & T, move
in consistent patterns from product to product. Exploring 6 diverse impacts in the U.S. -cropland, nitrogen, irrigation water, carbon emissions, building materials, and life expectancy -we check to see whether joint trajectories of C & T show a family resemblance. We also look
to see whether they move in tandem or independently. Along the way we revisit the power of
the ImPACT identity to compare the environmental leverages of consumer behavior and
producer efficiency, quantitatively.
* Waggoner, P.E., and Ausubel, J. H. 2002. A framework for sustainability science: A
renovated IPAT identity. Proc. National Acad. Sci. (US) 99:7860-7865.
On line at http://phe.rockefeller.edu/ImPACT/ImPACT.pdf
Four decades of U.S farm experience set the stage for
exploring patterns of consumers’ behavior and
producers’ efficiency.
Clearing and tilling cropland to feed a population P impact the environment. In
addition to depending on P, the impact’s extent also depends on income A, on
consumption of crops/GDP C, and finally on producers’ cropland/crop T. To ease
comparison among crops and other products we shall examine, we refer values to the first
year of the record, which is 1961 for crops. On the logarithmic coordinates of our
graphs, ten percent more C or T moves points up by 0.1; doubling moves them up by 0.7.
During almost four decades, workers more than doubled income A. At the same
time, U.S. consumer behavior cut C by just less than half. And producer efficiency
halved U.S. land/crop T by doubling yields.
Over the span of four decades, both C and T generally moved down. But
sometimes for short periods they moved in opposite directions.
Income A and Crop C and T
per 1961
1.5
ln A, C or T
1.0
A
0.5
C
0.0
1960
-0.5
T
1970
1980
1990
2000
-1.0
ImPACT Patterns Waggoner Ausubel page 2
Focus on their joint patterns by graphing behavior C
directly against efficiency T.
Although graphing T vs. C below rather than T vs. time as before shifts
coordinates, efficiency T still changes up and down. A 0.7 lower T means half as many
acres/bushel because bushels/acre double. Now, however, consumer behavior C
changes from right to left. C moving 0.7 leftward means the fraction of GDP expended
on crops halves.
Two patterns stand out. In brief periods as near dry 1983 the data points moved
diagonally left and up. When the U.S. crop fell as during the 1983 drought,
cropland/crop T rose. At the same time because GDP changed little, crop/GDP C
decreased leftward. Thus the zigzagging.
Over the span of four decades and several zigs and zags, alarms and excursions
however, a general trend carried C leftward and T down. Consumer behavior generally
dematerialized consumption leftward, and producer efficiency generally lowered
land/crop T by greater yields. Over the span, producer efficiency lowered land/crop T
by 0.8, a bit more than consumers’ 0.6 dematerialization of C leftward.
So relating C & T did not reveal a single consistent pattern. Rather it revealed
two patterns: 1) Short zigzags and 2) a long trend left of dematerialization combined
with a long trend down of less land/crop. And the trends quantified the leverage of
behavior and efficiency.
Crop T vs C
annual per 1961
1961
0
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
-0.2
1983
ln(T)
-0.4
-0.6
2000
C -0.6
T -0.8
-0.8
-1
ln(C)
ImPACT Patterns Waggoner Ausubel page 3
The rise and maturing of new technology cause
another pattern of C & T.
Following World War II, inexpensive, synthetic nitrogen fertilizer appeared in
farming as a new technology, relieving the mining of guano deposits and also relieving
depletion of the nitrogen in farm soil. When C vs. fertilizer/crop T is graphed, crop/GDP
C, of course, still dematerializes leftward as in the previous graph. In the new graph
below, however, nitrogen fertilizer/crop T rose for decades as U.S farmers exploited the
new technology. Then about 1983 an opposite trend of falling T started. With the
maturing of fertilizer technology from 1983 onward, farmers began using less fertilizer to
grow the national crop. Experience taught producers to apply the new technology of
fertilizer more efficiently.
To the previous patterns of zigzags and continuing fall of T while C
dematerializes, new technology adds a third pattern of a rise followed by the start of
falling T.
Nitrogen fertilizer T vs C
annual per 1961
1
1983
0.8
ln(T)
0.6
0.4
2000
0.2
0
-0.7
-0.6
-0.5
-0.4
-0.3
ln(C)
-0.2
-0.1
0
1961
ImPACT Patterns Waggoner Ausubel page 4
Improvements can slow as well as start.
In addition to land and nitrogen, crops need water. In the graph below
crops/GDP C remains as defined before and dematerializes leftward as before. In the
new graph, however, efficiency T becomes the irrigation water drawn per all U.S crop
production. Higher yield per water withdrawn from wells and canals and applied to
irrigated acres would cut water/crop T, obviously. A smaller role of irrigation in
national crop production also could cut our T of water/all crops .
The graph of C vs. T shows the familiar, leftward dematerialization of C. The
newly defined T for irrigation displays a new pattern: An episodic decrease from 1970
to 1985. A likely cause is the sharply less withdrawal of ground water in 1985 than
1980, ending progressive increases in withdrawals. After that sharp decrease, the
irrigation-water/all crops T held steady as more efficient water use compensated for a
small expansion of irrigated acreage.
The episodic fall of T for irrigation water during the 1980s adds still another to
our growing collection of different C vs. T patterns.
Irrigation T vs C
5-yr per 1960
1960/61
0.1
1970
-0.6
-0.5
-0.4
-0.3
-0.2
ln(T)
-0.7
0
-0.1
-0.1
0
-0.2
1995
C -0.5
T -0.4
-0.3
1985
-0.4
-0.5
ln(C)
ImPACT Patterns Waggoner Ausubel page 5
Slow improvement of one of the pair C & T needn’t
constrain improvement in the other.
For a new subject, we explore the consumption of energy and emission of the
greenhouse gas, carbon dioxide to produce the energy. Consumer behavior levers
emission with less energy/GDP C. Producers lever emission with less emission/energy T.
The graph of C vs. T shows that U.S consumers dematerialized energy/GDP C
about 2% per yr, moving C leftward 0.36 during the 18 years of 1980/98. During the
same 18 years, U.S. energy producers were able to improve or lower carbon dioxide
emission/energy only about one-tenth as fast.
The good news from this pattern of C & T is that consumers can improve
behavior despite producers’ slow progress improving T. Alternatively, producers could
presumably improve efficiency even if consumers were unable to dematerialize.
Carbon T vs C
annual per 1980
1988
-0.4
-0.3
-0.2
1980
0
-0.1
-0.01
ln(T)
-0.02
-0.03
1998
C -0.36
T -0.04
-0.04
-0.05
-0.06
ln(C)
ImPACT Patterns Waggoner Ausubel page 6
0
Producers’ efficiency may display little trend while
consumer behavior goes through tumultuous changes
Consider buildings and the cement and lumber to produce them. For building, we
defined C as value of new construction put in place divided by the GDP. During 1965/97
building went through cycles of boom and bust, which sped, slowed and even reversed
dematerialization of C.
How did producers’ efficiency T fare during the tumult of building? One can
define a cement/building T by dividing the tons of cement consumed in America by
construction value. Or a lumber/building T from the volume of lumber plus plywood.
The two T’s declined a bit 1965/80. They then wobbled until 1990. During the 1990s
while C scarcely changed, T cement went up a bit while T lumber fell a bit.
Unlike the pattern of regular dematerialization of energy in the preceding graph,
building changed irregularly. Like efficiency in carbon emission, the T for cement or T
for lumber resisted change. But adding a new pattern, dematerialization of building C
was unsteady, while T for its materials changed little and erratically.
Cement & lumber T vs C
annual per 1965
0
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
-0.05
ln(T)
T cement
-0.1
-0.15
T lumber
-0.2
ln(C)
ImPACT Patterns Waggoner Ausubel page 7
C may move right as well as dematerialize left.
With the exception of some zags among zigs in the preceding graphs of C vs. T,
C always dematerialized left. Is dematerialization universal?
An income elasticity of (b-1) connects C to A. The b is the income elasticity of
per capita consumption. For a necessity like food, b is less than 1, making the C’s
elasticity (b-1) negative. That is, if b is 0.7, raising income A by 10% dematerializes C
leftward by (0.7-1.0) times 10% or 3%. So the income elasticities less than 1 of such
necessities as we have examined combined with rising income to dematerialize C
leftward in our graphs of C & T. To show C moving right in a graph of C & T, we
must find a b greater than 1.
From 1987 to 2000 U.S. health-care expenditure per capita rose faster than
income A. The ratio of health-care to income change corresponds to an income
elasticity of per capita health-care expenditure of 1.4. The b of 1.4 makes the elasticity
(b-1) of health-care/GDP C a positive 0.4 instead of the negative elasticities that
dematerialized C in the previous examples. Thus, C may move right as well as
dematerialize left.
To complete a C & T graph, we need a T. Although one can hope health care
improves quality of life, we don’t know how to quantify it. On the other hand, we can
quantify national life expectancy, the product of population times life expectancy.
More than medicine extends life, and we go to the doctor for more than life-threatening
complaints. But we definitely go to the hospital if our life is threatened, and much will
be spent on us then.
So to illustrate something that does not dematerialize in a C & T graph, we
define health-care expenditure/GDP C and national life expectancy/health-care
expenditure T. T declined because national life expectancy extended although not as
fast as health-care expenditure increased.
For our exercise, one significant result is showing dematerialization is not a
universal pattern. Some parts of the economy, such as health care and education, are
capturing more expenditures while food and water win relatively less. Little thought
has gone into how the materializing sectors affect the environment.
Health T vs C
annual per 1987
ln(T) Life/Health care
cost
1987
0.0
-0.1 0.0
0.1
-0.2
0.2
0.3
1992
-0.3
-0.4
-0.5
2000
ln(C) Health care cost/GDP
ImPACT Patterns Waggoner Ausubel page 8
Consumer behavior and producer efficiency move
on diverse paths--graphically.
Referring our examples to the first year of their record and superimposing them
on a single chart of C & T, draws a synoptic chart of their diverse patterns. With zigs and
zags of good years and bad, crop consumption C dematerialized and producers’ use of
land shrank. With the same dematerialization, fertilizer per crop rose rapidly and then
started down, and irrigation water used per all crops fell in a dramatic episode. The slow
change of carbon dioxide emission per energy T did not keep consumers from cutting
energy/GDP C. Changing C irregularly, building cycles cause irregular—even reversed-time-lines along the C axis and draw confused courses of efficiency T. The
dematerialization of C may typify necessities, but health care demonstrates
dematerialization is not universal.
Diverse paths
1
0.5
ln(T)
Fertilizer
Cement
Lumber
-0.7
-0.5
Irrigation
CO2
0
-0.3
-0.1
0.1
-0.5
Health
Cropland
-1
ln(C)
ImPACT Patterns Waggoner Ausubel page 9
0.3
In the End.

With C, consumers reveal their behavior as they spend their income A.
With T, producers show their efficiency avoiding impact to fill consumers’
wants.

Graphing behavior C vs. efficiency T shows diverse patterns in the U.S. It
highlights the lack of a general connection between C & T. Thus neither
consumers nor producers need wait for the other to mitigate impact.

When consumers’ behavior lifts income elasticity over 1 and income rises,
C increases. Commonly, as for necessities, however, consumers’ behavior
causes an income elasticity of consumption/capita less than 1 and thus
negative elasticity of C. So commonly, C dematerializes.

Graphing C vs. T shows the relative leverage that consumers & producers
exert on impact. Consumers’ improvement of behavior C challenges
producers to improve efficiency T.

By levering C & T differentially rather than in a set pattern, the actors
demonstrate the merit of ImPACT separating A, C & T--quantitatively.
ImPACT Patterns Waggoner Ausubel page 10