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Living sustainably means balancing our consumption, our technology choices and our population numbers in order to live within the resources of the planet. It means maintaining a stable and healthy environment for both humanity and biodiversity.

The implications are radical. As a minimum a sustainable society, i.e. one that could physically be sustained indefinitely, would need a stable or reducing population, very high levels of reuse and recycling, 100% renewable energy and no net loss of soil and biodiversity. No country is yet near it.

We are already eating into our capital, collectively consuming the renewable resources of 1.5 planets, according to the respected World Wildlife Fund / Global Footprint Network Living Planet Report.

There are no magic numbers, only trade-offs. Any given area of land can sustain many more very low-consuming poor people at bare subsistence than it can very high-consuming rich people living like millionaires. Better technology always helps; but basically, the richer we all become, the fewer of us the planet, or any country in it, can sustain; and the more of us there are, the lower our sustainable standard of living will be.

The choice is fewer who are richer, or more who are poorer.

Population Matters seeks an optimal balance, offering the best quality of life, not the greatest quantity of possessions. This implies modest but reasonably comfortable standards of living free from hunger or insecurity, which enables fulfillment without increasing physical consumption. Only non-physical things — like quality of relationships, intelligence, education, knowledge, skills, health, arts, spiritual growth, respect, fun — can increase indefinitely in a physically finite world.

Sustainable business and governmental policies would ensure the take-up of renewable energy and material sources while phasing out those with adverse side effects. Increased effort is needed to minimise waste of energy, water, food and other commodities. In a finite world even renewable resources are only available in limited quantities.

Halting population growth and in many countries reversing it, is a vital part of living sustainably. In some societies, population growth has already slowed or stopped. Typically, the empowerment of women and improved availability of contraception have played major roles.

Compared with the challenge of asking people to reduce their living standards or change the fundamental technological basis of their society, approaches seeking a reduced birth rate are low cost and proven. The unborn people who never existed, and all their non-existent descendants in perpetuity, have no impact on our planet.

Gradually reducing our numbers back to the levels of one or two generations ago is one of the best ways of addressing the environmental and resource challenges we face.

Simple example
Take a simple example; a community has an aquifer of fossil groundwater, like a large water tank. The weather is reliable where they live and 100 m3 of rainwater are added every day. To live sustainably, the community can use up to 100 m3 of this water a day. If they use more one day they have to use less the next. The fact that the tank/aquifer is large and was full when they began beguiles some members of the community into believing they can use more. But their leaders resist; simple maths tells them that however large the tank/ aquifer they cannot take out more than is put in, otherwise the tank/aquifer will eventually become empty. Yet in huge areas of the world, notably China, South Asia and even the USA, groundwater for irrigation and households is depleting daily. One day the pumps will run dry and stop.

Read more about sustainability.

Read more about carrying capacity.

Read more about biocapacity and ecological footprinting.

Read more about new economic models.

Read Professor Albert A. Bartlett's writings on sustainability.