Putting economics before ecology has a devastating effect on the planet. But while solutions for sustainable development already exist, political will is sadly missing.

So how many Planet Earths do you think we will need by 2050 to keep humankind in the style to which we have become accustomed? Two? Three? Half a dozen? It's an absurd question, of course, and there's an absurd answer: two Planet Earths would apparently suffice, according to a Worldwide Fund for Nature (WWF) report published recently. But it's nothing like as absurd as the fact that there's not a single world leader prepared to give more than the most spurious consideration to our imminent collision with ecological reality.

WWF's Living Planet report provides an annual snapshot of the state of the critical ecosystems we depend on, and humankind's total "ecological footprint" - a measure of our collective use of renewable natural resources such as crop land, grazing land, forests, fishing grounds and so on. The "footprint" is a neat if simplistic way of getting a handle on the degree to which we can claim to be using these renewable resources sustainably.

WWF's "ready reckoner" sets the total of productive land and sea at about 11.4 billion hectares; divide by 6 billion (the current world population) and you get the magic number 1.9 hectares per person. Having crunched a huge amount of data from around the world, the average rate of use for 1999 emerges at 2.3 hectares per person - already 20% above the Earth's basic biological capacity of 1.9 hectares per person. Fast forward to 2050 (with a projected population of around 9 billion), and that average use rises to around 4 hectares per person - an ecological deficit equivalent to one whole Planet Earth.

We'd never get that far of course - feedback from collapsing natural systems would be so severe that we would be forced into emergency "coping strategies" long before the crunch - but at what cost then, so late in the day, to our economies, and to our democracies?

This is just one of a battery of curtain-raising reports that were published in the run-up to the World Summit on Sustainable Development in Johannesburg. Nothing new there. Big international events of this kind are always preceded by apocalyptic warnings of bad times ahead.

Not so long ago, however, these warnings inspired heated rebuttals from governments, often accompanied by crude attempts to disparage the scientific credentials of those offering the warnings. These days, all we get is silence. Hands-off, stony-faced, heard-it-all-before silence.

The truth is they can't rebut these warnings. The data used in reports like that of the WWF come not from "flaky, politically-motivated NGOs", but from the UN, international agencies, government-funded research programmes, and academic experts. Year on year, the data gets stronger and stronger. For lack of an even halfway adequate response, politicians keep their mouths shut.

And therein lies the real problem. Whatever our politicians may say about the importance of "evidence-based policy-making", of putting science at the heart of efforts to build a more sustainable, equitable world, their silence is in effect a betrayal of science.

If policy truly reflected what we now know about the state of the planet (in terms of climate change, water resources, disappearing habitats, deforestation, overfishing, growing numbers of environmental refugees, and so on), the political declarations such as those coming out of the World Summit would be very different from the anaemic and duplicitous efforts to date. What we have is ideology-based policy, with science deployed in a partisan and self-interested way to justify political expedience.

When George Bush was thrashing around to justify ideological abhorrence for the Kyoto protocol, he not only impugned the integrity of world-class scientists involved in the Inter-Governmental Panel on Climate Change (IPCC), but he totally ignored the judgement of the US Academy of Sciences (to whom he had turned in the hope of getting something more to his liking), which emphatically endorsed the findings of the panel.

    next > Page 1 of 2