When We "Hit the Wall"
by Roy W. Brown
The following article is from Free
Inquiry magazine, Volume 19, Number 2.
In a recent article in Science,
John Bongaarts of the Population Council in New
York wrote about the demographic impact of falling fertility rates.  Average human fertility has been falling
steadily for the past 30 years, from six or seven children per woman in the early part of
this century to just three or four children per woman today. But that number is still well
above replacement level - so each human generation is still bigger than the last. As
Sergei Kapitsa and others have shown, for many centuries world population has approximated
more closely hyperbolic growth as opposed to the exponential growth foreseen by Malthus -
in other words, an explosion.  From just 1.7
billion in 1900 our population will top 6 billion sometime this year. The latest U.N.
projections  show population continuing to
rise at least until the middle of the twenty-first century and possibly beyond, with
another 3 billion mouths to feed within the next two or three generations.
But, as the Worldwatch Institute has pointed
out, the U.N. projections are based purely on current demographic trends and take no
account of the ability of the Earth's resources to sustain humanity in such numbers.  Will the outcome be a hard or a soft landing for
humanity? Current indications are that, for some of us at least, the landing will be very
A Crash in the Distance
Ninety percent of future population growth is projected to occur in the poorest
countries and among the societies least able to cope. The industrialized nations, the
"North," have all experienced the demographic transition from the historically
high birthrate, high death-rate of pre-industrial society, through a second stage of rapid
population growth with high birthrate but increasing life expectancy, to the present stage
with birthrates at or below the replacement level of 2.1 children per woman. For these
societies long life is the norm and populations are relatively stable.
Over the next 50 years Europe will see its population stabilize or decline slightly as
individual couples exercise their choice of having smaller families. Most countries in the
developing world, in contrast, are still at the unsustainable second stage of transition
with rapidly growing populations. The challenge for these countries is whether they can
reduce their population growth rates fast enough to reach the sun-lit uplands of stability
or whether they will fall back into the demographic trap where population growth outstrips
the pace of economic development, leading to increasing poverty, sickness, and starvation,
increasing maternal and infant mortality, and possibly even to social breakdown. For these
societies, what has even more impact than the absolute numbers is the rate of
population growth, in some countries as high as 3% per year. That may not sound like much,
but it means they face a doubling of population in under 25 years. Imagine being dirt
poor, yet having to meet a demand for more food, more clean water, more housing, more
sanitation, more hospitals, more jobs, and so on every year, year after year. It simply
doesn't happen. Some cities in Asia and Latin America have actually seen their slums grow
at over 6% a year.
Reducing the national rate of population growth is now recognized by the governments of
all developing countries as a key to their future economic development, but for many of
them this recognition may have come too late. Life expectancy is already falling in large
parts of Africa as a result of the AIDS epidemic, and birthrates may well remain high
because individuals have neither the means nor any good reason to limit the number of
their children. For countries in the demographic trap the prospects are truly bleak, and
for those with populations already in excess of their long-term carrying capacity there
may be no way they can avoid an eventual population crash.
At the global level and in the longer term the outcome will be decided by the impact we
collectively make on our environment. We in the rich North have an unprecedented capacity
for environmental damage. We each consume as much energy, use as much water, and create as
much waste as about 40 people living in sub-Saharan Africa. We often hear the argument
that what is ruining the planet is not population growth in the South but our profligate
life-styles in the North. Unfortunately that argument breaks down as economic development
in the South begins to provide exactly the kind of high-consumption life-style we already
enjoy. So our total impact on the planet is a matter of both population numbers and
the average environmental impact each of us makes.
How many people can Earth support indefinitely? It depends entirely on consumption. If
we all shared the low-impact life-style of an African or Indian, Earth could perhaps
support 10 billion of us indefinitely. But with a typical North American way of life the
figure has been shown to be closer to 2.5 billion - and there are already 6 billion of us
on Earth. The late Julian Simon argued that population growth was a good thing; that by
any measure you care to choose life has gotten better as our population has grown, and
that it will therefore continue to do so. Unfortunately, it isn't possible to draw that
conclusion. Quite apart from the fact that there are measures by which life has most
assuredly become more difficult, the problem is that the resources of our planet - even
the renewable resources - are finite, and some, such as fresh water, cannot be
substituted. (See Lester Brown's article on just how stressed some of our resources are
How Will It End?
The big question is: Will we learn to live within our limits, and what will happen if
There are some good historical examples of what happens when population growth and
consumption outstrip the available resources. Easter Island is one that springs to mind.
When the island was first visited by Westerners in the seventeenth century, there was
evidence that it had once supported a far higher population and a higher level of
civilization than was then in evidence. In fact, it was thought that the island had once
been inhabited by a race of supermen. Research has revealed that a once-flourishing
society on a green and pleasant island outgrew its resources. Tree cover disappeared,
rainfall was reduced, and finally bitter conflict over the diminishing food and water
supply led to a population crash to perhaps only 10% of the number the island had once
supported. Almost all projections for future world population growth show it stabilizing
at some point in the future. While this may happen, it is not the most likely
scenario. Human population and Earth's resource base form a nonlinear dynamic system. Such
systems are typically chaotic and rarely, if ever, achieve stability. A more probable
outcome is for world population, like that of Easter Island, to overshoot its level of
long-term sustainability and then crash as crucial resources become exhausted and
environmental degradation sets in. Only global agreement and collective action on both
population and the environment seem likely to avert this outcome.
So how will it all end? It's in our hands. We, the inhabitants, consumers, and voters
of the rich countries of the North will determine the final outcome - either by our
actions, or by our inaction. As a minimum we should urge our governments to honor the
commitments they made at the International
Conference on Population and Development in Cairo to do more to help fund family
planning programs in developing countries - and to start to take more seriously the
environmental impact of our collective life-style. If we don't act now, our grandchildren
- even if they survive - will never forgive us.
- J. Bongaarts, "Policy Forum, Science's Compass," Science, 16 Oct
- S. P. Kapitsa, "The Phenomenological Theory of World Population Growth," Physics-Uspekhi
39 (1)(1996): 57-71.
- United Nations, World Population Estimates and Projections: 1998 Revision.
- L. Brown et al, "Beyond Malthus: Sixteen Dimensions of the Population Problem"
(Worldwatch Institute, 1998).
Roy W. Brown is founder, board member, and former chairman of the World Population Foundation in the Netherlands.