The Limits to Growth is a
1972 book modeling the consequences of a rapidly
growing
world population and finite
resource supplies, commissioned by the
Club
of Rome. Its authors were
Donella
H. Meadows,
Dennis L. Meadows,
Jørgen Randers, and
William W. Behrens III. The book used the
World3 model to simulate the consequence of
interactions between the Earth's and human systems. The book echoes
some of the concerns and predictions of the Reverend
Thomas Robert Malthus in
An Essay on the
Principle of Population (1798).
Five variables were examined in the original model, on the
assumptions that exponential growth accurately described their
patterns of increase, and that the ability of technology to
increase the availability of resources grows only linearly. These
variables are: world population, industrialization, pollution, food
production and resource depletion. The authors intended to explore
the possibility of a sustainable feedback pattern that would be
achieved by altering growth trends among the five variables.
The most recent updated version was published on June 1, 2004 by
Chelsea Green Publishing Company and
Earthscan under
the name
Limits to Growth: The 30Year
Update. Donnella Meadows, Jørgen Randers, and
Dennis Meadows have updated and
expanded the original version. They had previously published
Beyond the Limits in
1993 as a 20 year update on the original
material.Donella H. Meadows, Dennis L. Meadows, Jorgen Randers, and
William W. Behrens III. (1972).
The Limits to Growth. New York: Universe Books. ISBN
0876631650
In 2008 Graham Turner at the Commonwealth Scientific and Industrial
Research Organisation (
CSIRO) in Australia
published a paper called "A Comparison of `The Limits to Growth`
with Thirty Years of Reality". It examined the past thirty years of
reality with the predictions made in 1972 and found that changes in
industrial production, food production and pollution are all in
line with the book's predictions of
economic and
societal collapse in the
21st century.
Purpose
The purpose of
The Limits to Growth was not to make
specific predictions, but to explore how exponential growth
interacts with finite resources. Because the size of resources is
not known, only the general behavior can be explored. The authors
state in a subsection titled
The Purpose of the World
Model:
In this first simple world model, we are interested
only in the broad behavior modes of the populationcapital system.
By behavior modes we mean the tendencies of the variables
in the system (population or pollution, for example) to change as
time progresses. A variable may increase, decrease, remain
constant, oscillate, or combine several of these characteristic
modes. For example, a population growing in a limited environment
can approach the ultimate carrying capacity of that environment in
several possible ways. It can adjust smoothly to an equilibrium
below the environmental limit by means of a gradual decrease in
growth rate, as shown below. It can overshoot the limit and then
die back again in either a smooth or an oscillatory way, also as
shown below. Or it can overshoot the limit and in the process
decrease the ultimate carrying capacity by consuming some necessary
nonrenewable resource, as diagrammed below. This behavior has been
noted in many natural systems. For instance, deer or goats, when
natural enemies are absent, often overgraze their range and cause
erosion or destruction of the vegetation.
A major purpose in constructing the world model has
been to determine which, if any, of these behavior modes will be
most characteristic of the world system as it reaches the limits to
growth. This process of determining behavior modes is "prediction"
only in the most limited sense of the word. The output graphs
reproduced later in this book show values for world population,
capital, and other variables on a time scale that begins in the
year 1900 and continues until 2100. These graphs are not
exact predictions of the values of the variables at any particular
year in the future. They are indications of the system's behavioral
tendencies only.
The difference between the various degrees of
"prediction" might be best illustrated by a simple example. If you
throw a ball straight up into the air, you can predict with
certainty what its general behavior will be. It will rise with
decreasing velocity, then reverse direction and fall down with
increasing velocity until it hits the ground. You know that it will
not continue rising forever, nor begin to orbit the earth, nor loop
three times before landing. It is this sort of elemental
understanding of behavior modes that we are seeking with the
present world model. If one wanted to predict exactly how high a
thrown ball would rise or exactly where and when it would hit the
ground, it would be necessary to make a detailed calculation based
on precise information about the ball, the altitude, the wind, and
the force of the initial throw. Similarly, if we wanted to predict
the size of the earth's population in 1993 within a few percent, we
would need a very much more complicated model than the one
described here. We would also need information about the world
system more precise and comprehensive than is currently
available.
Exponential reserve index
One key idea that
The Limits to Growth discusses is that
if the rate of resource use is increasing, the amount of reserves
cannot be calculated by simply taking the current known reserves
and dividing by the current yearly usage, as is typically done to
obtain a static index. For example, in 1972, the amount of chromium
reserves was 775 million metric tons, of which 1.85 million metric
tons were mined annually (see
exponential growth). The static index is
775/1.85=418\text{ years}, but the rate of chromium consumption was
growing at 2.6% annually (
Limits to Growth, pp 54–71). If
instead of assuming a constant rate of usage, the assumption of a
constant rate of growth of 2.6% annually is made, the resource will
instead last
 \frac{\ln (\ln (1.0 + 0.026)\times(418 + 1))}{\ln (1.0 +
0.026)}=\text{93 years}
(note that the book rounded off numbers).
In general, the formula for calculating the amount of time left for
a resource with constant consumption growth is :
 y=\frac{\log(1(1g)\times\frac{R}{C})}{\log(g)}1
where:
 y = years left;
 g = 1.026 (2.6% annual consumption growth);
 R = reserve;
 C = (annual) consumption.
The authors list a number of similar exponential indices comparing
current reserves to current reserves multiplied by a factor of
five:
 { class="wikitable"
The static reserve numbers assume that the usage is constant, and
the exponential reserve assumes that the growth rate is constant.
For petroleum, neither the assumption of constant usage or the
assumption of constant exponential growth was correct in the years
that followed.
Whether intended or not, the exponential index has often been
interpreted as a prediction of the number of years until the world
would "run out" of various resources, both by environmentalist
groups calling for greater conservation and restrictions on use,
and by skeptics criticizing the index when supplies failed to run
out. For example,
The
Skeptical Environmentalist(page 121) states: "
The
Limits to Growthshowed us that we would have run out of oil
before 1992." What
The Limits to Growthactually has is the
above table, which has the
current reserves(that is no new
sources of oil are found) for oil running out in 1992 assuming
constant exponential growth.
Criticism
The Limits to Growthattracted controversy as soon as it
was published.
Robert M.Solow from MIT, complained about the weak base of data on which
The Limits to Growths predictions were made (Newsweek,
March 13, 1972, page 103).Dr. Allen Kneese and Dr. Ronald
Riker of Resources for the Future (RFF) stated:
"The authors load their case by letting some things
grow exponentially and others not.
Population, capital and pollution grow exponentially in
all models, but technologies for expanding resources and
controlling pollution are permitted to grow, if at all, only in
discrete increments."
Some critics falsely claimed that
The Limits to
Growthpredicted oil running out in 1992 among other natural
resources. The book's real conclusion was that it was very unlikely
that resources would end in 1992. The 1992 date was extrapolated
out of context by critics dedicated to demolish "Limits" work, and
is still present in common knowledge.
It should be noted, that the authors of the report accepted that
the thenknown resources of minerals and energy could, and would,
grow in the future, and consumption growth rates could also
decline. The theoretical expiry time for each resource would
therefore need to be updated as new discoveries, technologies and
trends came to light. To overcome this uncertainty, they offered an
upper value for the expiry time, calculated as if the known
resources were multiplied by two. Even in that case, assuming
continuation of the average rate of consumption growth, virtually
all major minerals and energy resources would expire within 100
years of publication (i.e., by 2070). Even if reserves were two
times larger than expected, ongoing growth in the consumption rate
would still lead to the relatively rapid exhaustion of those
reserves. On the other hand, reserves may continue to grow,
considering the large amounts of minerals in the planet
Earth.
In 2008 researcher Peter A. Victor wrote, that even though D.H.
Meadows et al. probably paid too little attention for
pricemechanism's role in adjusting, their critics have paid too
little. He states that
Limits to Growthhas had a huge
impact on how we still think about environmental issues and notes
that the models in the book were meant to taken as predictions
"only in the most limited sense of the word" as they wrote.
Yale economist
Henry C.Wallichlabeled the book "a piece of
irresponsible nonsense" in a
Newsweekeditorial dated March 13, 1972.
Wallich's
main complaints are that the book was published as a publicity
stunt with great fanfare at the Smithsonian in Washington, and that there was insufficient
evidence for many of the variables used in the
model.According to Wallich, "the quantitative content of the
model comes from the authors' imagination, although they never
reveal the equations that they used." Considering that the detailed
model and Meadows' et al. justifications were not published until
1974 (two years after
The Limits to Growth) in the book
Dynamics of
Growth in a Finite World, Wallich's complaint about "the
peculiar presentation of their work and by their unscientific
procedures" had merit at the time.
See also
Books
References
Editions
 ISBN 0876631650, 1972 First edition
 ISBN 0876632223, 1974 Second edition (cloth)
 ISBN 087663918X, 1974 Second edition (paperback)
 ISBN 193149858X, 2004 Limits to Growth: The 30Year
Update
External links
Video and Audio

Years 

Resource 
Consumption growth rate, annual 
Static index 
Exponential index 
5 times reserves exponential index 

Chromium 
2.6% 
420 
95 
154 

Gold 
4.1% 
11 
9 
29 

Iron 
1.8% 
240 
93 
173 

Petroleum 
3.9% 
31 
20 
50 