Environment
Two-thirds of world's
resources 'used up'
Tim
Radford
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 pressure.
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 industrial fishing.
* Since 1980, about 35% of mangroves have been lost, 20% of
the world's coral reefs have been destroyed and another 20%
badly degraded.
*Deforestation and other changes could increase the risks
of malaria and cholera, and open the way for new and so far
unknown disease to emerge.
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 our children."
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 luxury.
"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 delivers."
The writer
is science editor, The Guardian. The article was first published
in The Guardian.
Copyright
(R) thedailystar.net 2005
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