in the aggregate, we contribute only a

tiny fraction of the total.

But that's when we compare

ourselves with the rest of the world.

Within our own country, the effect is

reversed. When governments want to

clobber us, they talk about our

aggregate consumption. The ACT

Government, for example, tells us

our aggregate daily water

consumption, relative to a pre-set

target. If the Government wanted to

make us feel good about our water

consumption, it would tell us the per

capita figure.

This is because, when we want to

measure how we are going, we prefer

to talk about trends over time. If

consumption rises less rapidly than

the population does, we obtain a per

capita decline. This leads some

people to argue that we can

''decouple'' our consumption from

our ecological footprint, despite the

fact that our aggregate impact is

greater than ever.

How far policy analysts go with this

''decoupling'' argument tends to

depend upon how much they believe

in the power of markets. Economists,

by and large, believe that if we get the

prices right, market forces will do the

work of making us more sustainable.

We don't actually need to change

the way we think, because we are all

self-interested utility maximisers,

and if we are given the incentives to

change what we do, all will be well.

But that still leaves the population

question hanging in mid-air.

Economists tend to be wary of it,

because of the complexity of the

relationship between population

growth, technological change and

economic growth.

They point to the immense power

of markets and modern technology

to improve living standards in poor

countries, and to the fact that, once

people become sufficiently rich for

children to be a net cost, they

spontaneously lower their

reproduction rate. When it comes to

rich countries, however, economists

are less comfortable about declining

birth rates, seeing population ageing

and eventual decline as a threat to

further improvements in living

standards.

The Greens are in several minds on

the question of population. Most are

well aware that population growth is

detrimental to the environment. But

most don't want to talk about it,

because to do so in this country

would mean cutting back on

immigration, and immigration is a

difficult subject to discuss publicly. It

is less controversial to preach

individual restraint. So the Greens

want us all to cut back, to improve

the insulation of our buildings, to put

solar panels on our roofs, to recycle

as much as possible, to use less. If we

all do it, all will be well.

For its part, business appears to

have no doubts about population

increase: more people means more

customers, and more customers

mean higher profits. Business can

afford to say this, because in general,

business does not pay for the extra

costs that high rates of population

growth impose on society as a whole.

Governments, ever opportunistic,

avoid the ''population'' word all

together. Rather than managing

population growth more carefully,

successive federal governments

prefer to use immigration as an on-

off tap, increasing the flow when

economic growth is strong, and

reducing it when it falls away. The

states, territories and local

government have no choice but to try

to accommodate the extra people as

best they can.

So, that leaves the rest of us. We are

not against immigration per se, but

we do understand that more people

means more stress on our

environmental resources. And

beyond that realisation, comes

another. We appreciate the need to

reduce water and energy use, to re-

use and recycle, but if we do the

heroic thing and reduce our

consumption, how much of our

sacrifice will be negated by

population increase?

As a society, we need to think

carefully, and much more honestly

than in the past, about where our

current growth models are taking us.

Do we really believe that

governments have the will, and the

skill, to manage the myriad

competing pressures involved?

Reducing population growth will

not solve all our environmental

problems they are much too

complicated for that. But it will, at

least, give us a little more time to sort

out what we really mean by

sustainability, as well as taking some

of the pressure off our urban water,

planning and transport systems.

Dr Jenny Stewart is associate professor

of public policy at the University of

Canberra.