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Thirty Years Later the Idea of Limits to Growth Is More Important Than Ever
Elizabeth Sawin
© Sustainability Institute
2 September 2004
Beth Sawin is a mother, biologist and systems analyst who lives in Hartland Vermont and works at Sustainability Institute (www.sustainer.org). Beth's columns appear in Grist Magazine (www.gristmagazine.com). Contact her at bethsawin@sustainer.org to receive her monthly column on systems and sustainability.
Pick up the newspaper on any day and you are likely to find plenty of bad news about humanity’s impact on the Earth. From the global to the regional to the local, if you are feeling pessimistic you can find all sorts of "proof" that humanity is well on the way to self-destruction.
If you keep looking, beyond the bad news you will find good news as well –
although usually not on the front page. Some fisheries are being managed sustainably
and have been for decades. Production of organic food is rising. The ozone layer
is stabilizing. Communities are preserving land and building bike paths and
setting their own greenhouse gas emission goals. New technologies and the evolution
of old ones could make feeding, transporting, sheltering, and cleaning up after
ourselves much more efficient. Based on all this good news, an optimist might
say that all we need is more of the same to glide in to a secure future.
It can be tempting to try to figure who’s right - the optimists or the
pessimists. But that whole question can also be a distraction, like trying to
puzzle out whether the boat you are paddling through rushing water is doomed
or safe instead of concentrating on reading the current and paddling with as
much power and sense of direction as you can muster.
If you’re willing to leave the pessimists and the optimists to their arguments
and instead are looking for a guide to paddling our particular river, our moment
in time with it’s mixture of troubling trends and hopeful developments,
then seek out the newly published, thirty year update to Limits to Growth a
book first published in 1972. (Limits to Growth - The 30 Year Update by Donella
Meadows, Jorgen Randers and Dennis Meadows, published by Chelsea Green Publishing
Company). It won’t settle the argument between the pessimists and the optimists,
but it does help explain how our global society has ended up beyond the carrying
capacity of the Earth’s systems and what it will take to ease down below
the limits.
The book reports on the lessons from a computer simulation model first built
by the authors and other young researchers at MIT in the early 1970s when they
were trying to understand the dynamics of a growing human society’s approach
to the carrying capacity of the planet. Why and how was the system approaching
the carrying capacity in the first place? And what sort of outcomes might be
expected if society did in fact reach or exceed some of those limits?
To build their model the researchers made four critical assumptions, descriptions
of which I have copied from an unpublished piece Donella Meadows wrote about
the modeling work:
· Growth is inherent to the present human value system, and growth of both the
population and the economy, when it does occur, is exponential.
· There are physical limits to the planetary sources of materials and energy
that sustain the human population and economy, and there are limits to the planetary
sinks that absorb the waste products of human activity.
· The growing population and economy receive signals about physical limits that
are distorted and delayed. The human response to those signals is also delayed.
· The planetary limits are not only finite, but erodable when they are overstressed
or overused.
These four assumptions are enough to produce, in the simulated computer "world,"
the same patterns of behavior that we see in our real world, patterns to which
we tend to gives labels such as climate change, or Gulf Hypoxia, or fishery
crashes.
In the model runs presented in the book (which are updated from the 1970s version),
without anyone "intending it," the growing population and economy
drain down resources and produce wastes at a growing rate. Because the consequences
of these falling resources and rising wastes don’t immediately influence
the growth rate of the population/economy system, that system continues to grow
and "overshoots" the limit, just as has happened for C02 in the atmosphere,
nitrogen in the Gulf of Mexico, cod fishing in Georgia’s Bank, and dozens
of other examples.
The authors report on what it takes in their simulated world to recover from
overshoot and avoid collapse – a combination of constraints on growth and
adoption of more efficient technologies, and they suggest the kinds of work
this will require in the real world, including:
· Extend the planning horizon
· Improve the signals
· Speed up response time
· Minimize the use of non-renewable resources
· Prevent the erosion of renewable resources
· Use all resources with maximum efficiency
· Slow and eventually stop exponential growth of population and physical capital.
There’s much more in the book of course – useful data and clear graphics,
and, in the final chapter, thoughts about the attitude and skills it will take
to pull off the work of easing down below the limits. These features are reason
enough to read the book, but there is another, more important reason, as well.
For the thirty years that this book and others with similar messages have been
in existence the world’s leaders have been slow to acknowledge limits to
growth and slow to take action based on those limits. That puts the burden of
learning from Limits to Growth back on the rest of us. If the idea that we have
overshot the limits and must now ease down from them fits with your experience
of the world, then read the book, take from it what you can, and put it to use,
in your life, your conversations, and your strategizing for the future.
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