In 1987, the World Commission on Environment and Development put the idea of sustainability into these words:
A sustainable society is one that "meets the needs of the present without compromising the ability of future generations to meet their own needs."
From a systems point of view, a sustainable society is one that has in place informational, social, and institutional mechanisms to keep in check the positive feedback loops that cause exponential population and capital growth. This means that birthrates roughly equal death rates, and investment rates roughly equal depreciation rates, unless or until technical change and social decisions justify a considered, limited change in the levels of population or capital.
Such a society, with a sustainable ecological footprint, would be almost unimaginably different from the one in which most people now live. Before we can elaborate on what sustainability could be, we need to start with what it need not be.
Sustainability does not mean zero growth. Rather, a sustainable society would be interested in qualitative development, not physical expansion. It would use material growth as a considered tool, not a perpetual mandate. Neither for nor against growth, it would begin to discriminate among kinds of growth and purposes for growth. It would ask what the growth is for, and who would benefit, and what it would cost, and how long it would last, and whether the growth could be accommodated by the sources and sinks of the earth.
A sustainable society would also not paralyze into permanence the current inequitable patterns of distribution. For both practical and moral reasons, a sustainable society must provide sufficiency and security for all. A sustainable society would not be a society of despondency and stagnation, unemployment and bankruptcy that current systems experience when their growth is interrupted. A deliberate transition of sustainability would take place slowly enough, and with enough forewarning, so that people and businesses could find their places in the new economy.
A sustainable world would also not be a rigid one, with population or production or anything else held pathologically constant. One of the strangest assumptions of present-day mental models is the idea that a world of moderation must be one of strict, centralized government control. A sustainable world would need rules, laws, standards, bound- aries, social agreements and social constraints, of course, but rules for sustainability would be put into place not to destroy freedoms, but to create freedoms or protect them.
Some people think that a sustainable society would have to stop using nonrenewable resources. But that is an over-rigid interpretation of what it means to be sustainable. Certainly a sustainable society would use nonrenewable gifts from the earth's crust more thoughtfully and efficiently.
The authors do suggest a few general guidelines for what sustainability would look like, and what steps we should take to get there:
- Extend the planning horizon. Base the choice among current options much more on their long-term costs and benefits.
- Improve the signals. Learn more about the real welfare of human population and the real impact on the world ecosystem of human activity.
- Speed up response time. Look actively for signals that indicate when the environment or society is stressed. Decide in advance what to do if problems appear.
- Minimize the use of nonrenewable resources.
- Prevent the erosion of renewable resources.
- Use all resources with maximum efficiency.
- Slow and eventually stop exponential growth of population and physical capital.
The necessity of taking the industrial world to its next stage of evolution is not a disaster -- it is an amazing opportunity. How to seize the opportunity, how to bring into being a world that is not only sustainable, functional, and equitable but also deeply desirable is a question of leadership and ethics and vision and courage, properties not of computer models but of the human heart and soul.