ALMOST one-quarter of nature’s

resources are being gobbled

up by a single species, and it’s

not difficult to guess which one.

Based on figures for the year

2000, the most recent available,

humans appropriate 24 per cent

of the Earth’s production capacity

that would otherwise have gone

to nature.

The result is a gradual

depletion of species and habitats

as we take more of their resources

for ourselves. Things could get

even worse if we grow more plants

like palm oil and rapeseed for

biofuels to ease our reliance on

fossil fuels.

That is the message from a

team led by Helmut Haberl of

Klagenfurt University in Vienna,

Austria. Haberl and colleagues

analysed UN Food and Agriculture

Organization data on agricultural

land use in 161 countries covering

97.4 per cent of farmland.

By comparing carbon

consumption through human

activity with the amount of

carbon consumed overall,

Haberl’s team found that humans

use some 15.6 trillion kilograms of

carbon annually. Half was soaked

up by growing crops. Another 7

per cent went up in smoke as fires

lit by humans, and the rest was

used up in a variety of other ways

related to industrialisation, such

as transport (Proceedings of the National Academy of Sciences,

DOI: 10.1073/pnas.0704243104 ).

Haberl says that the Earth can

just about cope if we meet future

needs by producing food more

efficiently. This could be done

by intensifying agriculture on

roughly the same amount of

land as we use now. But we’re

asking for trouble, he says, if we

expand production of biofuels, as

the only fertile land available is

tropical rainforests.

“If we want full-scale

replacement of fossil fuels by

biofuels, this would have dramatic

implications for ecosystems,”

says Haberl. He warns that some

projections foresee four or

fivefold increases in biofuel

production. “This would at least

double the overall amount of

biomass harvested, which is about

30 per cent above ground at

present, but would increase to

40 or 50 per cent to meet these

biofuel targets,” he says.

This would mean clearing what

remains of the world’s rainforests

in countries such as Brazil and

Argentina. As well as wiping out

thousands of species, this would

have devastating effects on the

climate, he says. Unlike farmland,

forests help to seed rainfall

because they have high

evaporation rates.

“The less evaporation there

is, the less rainfall there is and

the whole system dries up,” he

says. Andy Coghlan ●

“Things could get even worse if

we grow more plants like palm

oil and rapeseed for biofuels to

ease our reliance on fossil fuels”

www.newscientist.com 7 July 2007 | NewScientist | 15

–More than our fair share–

Earth suffers as we gobble up resources

FERN

ANDO

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