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'Humanity at risk' from ecological debt
03 November 2007
From New Scientist Print Edition.
Catherine Brahic

It is a pity we have only one planet to live on. The latest planetary health assessment shows we need 1.4 Earths to sustain the average lifestyle. If we don't slow down, the report warns, "humanity is at risk".

The UN Environment Programme released its fourth Global Environment Outlook (GEO) report last week. And while the human ecological footprint is 21.9 hectares per person on average, the Earth's biological capacity is just 15.7 hectares per person.

According to the Global Footprint Network, we went into ecological debt on 6 October this year, having consumed more than the planet can regenerate in one year. Similar footprint calculations recently found that Cuba is the only nation developing sustainably (Ecological Economics, DOI: 10.1016/j.ecolecon.2007.08.017). So no matter how you spin it, we're in trouble.

GEO-4 contains an inventory of debt and its consequences. Five years in the making, it was put together by about 400 experts and reviewed by an additional 1000. Predictably, climate change is a major concern. "About half of our footprint is accounted for by the areas that are required to absorb our greenhouse gas emissions," says Neville Ash of the UNEP World Conservation Monitoring Centre in Cambridge, UK. "The other half is the land which produces our food, the forests which produce our timber, the oceans and rivers which produce our fish."

The inflated size of our footprint is partially the result of the growth of the human population. Currently estimated at 6.7 billion people, it could reach 8 to 10 billion by 2050.

Ash says we could sustain the current and projected population if we all lived sustainably, the question is how? Energy efficiency tops the list. For instance, energy demand is growing rapidly, especially in developing nations. But the GEO-4 authors say the resulting growth in emissions by 2020 could be halved using existing technology.

This may not be enough. Robin Hickman of Halcrow Group, an energy consultancy, and David Banister of the University of Oxford modelled different futures, each of which relied on technological innovation and a reduction in travel by individuals. They concluded that changes in transport behaviour must be implemented now if the UK government is to meet its goal of reducing emissions from travel by 60 per cent by 2030 (Transport Policy, vol 14, p 377).

From issue 2628 of New Scientist magazine, 03 November 2007, page 13

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