Two-thirds of world's resources 'used up'
Tim Radford, science editor
Wednesday March 30, 2005
The human race is living beyond its means. A report backed by 1,360
scientists from 95 countries - some of them world leaders in their
fields - today warns that the almost two-thirds of the natural
machinery that supports life on Earth is being degraded by human
The study contains what its authors call "a stark warning" for the
entire world. The wetlands, forests, savannahs, estuaries, coastal
fisheries and other habitats that recycle air, water and nutrients for
all living creatures are being irretrievably damaged. In effect, one
species is now a hazard to the other 10 million or so on the planet,
and to itself.
"Human activity is putting such a strain on the natural functions of
Earth that the ability of the planet's ecosystems to sustain future
generations can no longer be taken for granted," it says.
The report, prepared in Washington under the supervision of a board
chaired by Robert Watson, the British-born chief scientist at the
World Bank and a former scientific adviser to the White House, will be
launched today at the Royal Society in London. It warns that:
· Because of human demand for food, fresh water, timber, fibre and
fuel, more land has been claimed for agriculture in the last 60 years
than in the 18th and 19th centuries combined.
· An estimated 24% of the Earth's land surface is now cultivated.
· Water withdrawals from lakes and rivers has doubled in the last 40
years. Humans now use between 40% and 50% of all available freshwater
running off the land.
· At least a quarter of all fish stocks are overharvested. In some
areas, the catch is now less than a hundredth of that before
· Since 1980, about 35% of mangroves have been lost, 20% of the
world's coral reefs have been destroyed and another 20% badly
· Deforestation and other changes could increase the risks of malaria
and cholera, and open the way for new and so far unknown disease to
In 1997, a team of biologists and economists tried to put a value on
the "business services" provided by nature - the free pollination of
crops, the air conditioning provided by wild plants, the recycling of
nutrients by the oceans. They came up with an estimate of $33
trillion, almost twice the global gross national product for that
year. But after what today's report, Millennium Ecosystem Assessment,
calls "an unprecedented period of spending Earth's natural bounty" it
was time to check the accounts.
"That is what this assessment has done, and it is a sobering statement
with much more red than black on the balance sheet," the scientists
warn. "In many cases, it is literally a matter of living on borrowed
time. By using up supplies of fresh groundwater faster than they can
be recharged, for example, we are depleting assets at the expense of
Flow from rivers has been reduced dramatically. For parts of the year,
the Yellow River in China, the Nile in Africa and the Colorado in
North America dry up before they reach the ocean. An estimated 90% of
the total weight of the ocean's large predators - tuna, swordfish and
sharks - has disappeared in recent years. An estimated 12% of bird
species, 25% of mammals and more than 30% of all amphibians are
threatened with extinction within the next century. Some of them are
threatened by invaders.
The Baltic Sea is now home to 100 creatures from other parts of the
world, a third of them native to the Great Lakes of America.
Conversely, a third of the 170 alien species in the Great Lakes are
originally from the Baltic.
Invaders can make dramatic changes: the arrival of the American comb
jellyfish in the Black Sea led to the destruction of 26 commercially
important stocks of fish. Global warming and climate change, could
make it increasingly difficult for surviving species to adapt.
A growing proportion of the world lives in cities, exploiting advanced
technology. But nature, the scientists warn, is not something to be
enjoyed at the weekend. Conservation of natural spaces is not just a
"These are dangerous illusions that ignore the vast benefits of nature
to the lives of 6 billion people on the planet. We may have distanced
ourselves from nature, but we rely completely on the services it