In June 1987, The Brundtland Commission presented it to a wider world, providing it with a somewhat clumsy but widely accepted definition and a greatly enhanced political legitimacy.

Perhaps the greatest value of this, now ubiquitous, concept seems to lie in its ambiguity.   Almost everyone can buy into it by defining it to suit his or her own purpose.  To governments, it can conveniently mean continued development programmes, with some renewed emphasis on environmental protection.  To the environmental community, it signals strong brakes on economic growth.  To the businesses who espouse it, it probably means sustainable competitive advantage and not much change from business as usual.  But, negotiating around the table, all these constituencies often take the term to mean what they please, and come to agreements that ensure continuing dialogue and interaction.  The logic of the agreements to which they have become committed, however, later gently forces them to redefine their positions – and this often leads them towards better outcomes for life on our planet. 

The concept has its weak points too. There is, of course, a (possibly growing) number of constituencies that do not wish to have anything to do with sustainable development since they feel that we have already passed the limits it purports to save us from.  And there are those who feel that it gives a false sense of security by suggesting that any form of development can even be sustainable. There is considerable truth in this argument, particularly in the industrialised North.  But given the poverty, deprivation and disparity in the rest of the world, clearly the present state of affairs is not acceptable either. 

The greatest weakness probably lies in the difficulty with which a concept like sustainable development can be operationalised.  How do we define sustainable development so that it can be measured?  How does it translate into actions that we must take in our day to day lives?  How do we know when we are on the right track?

The simple answer is we can’t.

To redesign development to be sustainable, ironically, we need other concepts — concepts that can be quantified or characterised more precisely, communicated to the public and used as indicators and policy tools.  Such tools are now emerging and promise exciting new possibilities, not only for researchers, media and activists, but also for businesses and policy makers whose actions can impact our life support systems so profoundly.

Since these tools must be used for measuring, communicating and creating widespread understanding, they must be simple.  Yet, if they are to be used for policy making and restructuring the economy, they must also be relatively precise and unambiguous. 

One of the oldest of these is the “carrying capacity”.  This represents the maximum number of human beings (or other species under study) that can be supported by a given area (or specific resource base) without damaging its ability to support the same number in the future. 

The second is the “ecological footprint” – which is the area of land (not necessarily contiguous) that is needed to support a particular population at a particular standard of material use over a long period of time.  It is, in a sense, the inverse of the carrying capacity.  Although this is a more recent concept in the scientific literature, it is only fair to point out that Mahatma Gandhi had already given a classic example of it more than fifty years ago.  In response to a question whether India should aspire to the standard of living attained in England, he simply asked how many worlds would be needed to support such an India, given that most of this one is already taken up to maintain the tiny British Isles. 

My own current favourite is Factor 10.  Unlike the others, which are indicators, this is both an indicator and a goal.  It simply means that for development to be sustainable, the material intensity of our activities must be greatly reduced.  The anthropogenic flows of materials around the world are now beginning, in quantity, to compete with geologic flows.  This is clearly not tenable for long.  The material productivity of our technologies must be increased dramatically, at least by a factor of ten.  Factor 10 is not only desirable, but in many cases already possible.  And it is easy for anyone to understand, measure and verify.   q

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