Sustainability is when all people live within the limits of the Earth’s bio-capacity.

What is sustainability?

Sustainability is when all people – individuals, societies, nations – live within the limits of the Earth’s bio-capacity.


Bio-capacity is the amount of biologically productive land and sea area that can supply the resources a human population consumes, and to assimilate associated waste.

Ecological footprint

On the other hand, Ecological Footprint is a measure of what humans consume in terms of biologically productive land. Humanities’ ecological footprint is now about 1.5 times higher than the bio-capacity of the earth, and growing.

The fact that we are consuming more resources than the earth can sustainably provide means that we are now using up the earth’s natural capital to make up the shortfall. Natural capital are things like freshwater, soil, forest land, biodiversity, coral reefs and wetlands. This is unsustainable – using capital as if it is income ultimately leads to ruin.

Sustainability is the fundamental condition of any system that lasts. If we want to sustain the earth’s ecosystems we must stop consuming and degrading natural capital and live within the limits of the Earth’s bio-capacity.

In western, industrialised countries the average person has an ecological footprint several times larger than the average for the earth.

To live a sustainable life people must reduce their ecological footprint.

It is meaningful and useful to speak of some practices being “more sustainable” or “less sustainable.” Energy-saving compact fluorescent light bulbs are considered more sustainable than incandescent light bulbs, and so on. You can also talk of moving “towards sustainability,” or away from it.

Human nature

Through population growth, industrialisation and consumerism humans have changed the world’s environment in unprecedented ways. Climate change, habitat loss and species extinctions have occurred because of factors like pollution, soil degradation, deforestation and the introduction of noxious animals and pests.

The message is clear: we humans cannot keep consuming at the rate that we do. We must reduce our ecological footprint to sustainable levels for our own well-being and for the well-being of the whole planet.

Many people believe that reducing their footprint will deprive them but this is simply not the case. For the majority of people in the western world reducing consumption will actually increase their well-being for the simple reason that well-being is not based on how much we produce and consume, rather it is based on things like health, relationships, giving and self-improvement.

What is sustainability