http://www.commondreams.org/headlines02/0802-06.htm
Published on Friday,
August 2, 2002 in the lndependent/UK
World Atlas of Biodiversity
A Global Picture of Death, Damage and Destruction
Atlas produced by the United Nations demonstrates how mankind
is changing the world and driving thousands of species to extinction
Land
Scientists estimate
that over the past 150 years humans have
altered nearly 47 per cent of the Earth's land surface.
The World Atlas of Biodiversity, published by the United
Nations yesterday, suggests that the complex but delicate
interaction between terrestrial plants and animals will be
threatened on almost three quarters of the total land surface
within the next 30 years.
The terrestrial environment
extends over little more than
one quarter of the Earth's surface, or nearly 150 million
square kilometers (58 million square miles). It is the most
accessible to humans and has therefore suffered the most in
terms of environmental degradation and loss of species.
Dry land is characterized
by its extensive collection of
complex plants harboring a rich and diverse array of animals.
Forests and woodlands are the natural cover for much of the
world's land. Photosynthesis - the process used by plants to
convert sunlight into chemical energy - is most intense in
tropical forests, which are among the richest places in the
world in terms of biodiversity.
The Atlas says that
half of the area of forest that had
developed since the last ice age has since been cleared
or degraded by man. The decline is especially prevalent
today in the tropical rainforests of South-East Asia, the
Congo and parts of the Amazon. About 22 per cent of these
areas are used for farming, towns and other kinds of human
development. By 2032, scientists estimate this exploitation
may more than double to 48 per cent of the total land area
that they now cover.
Areas of the land that
are not covered by trees - such as
shrubland, deserts and tundra - tend to be poorer in terms
of biodiversity, with the exception of Mediterranean-type
shrub, which can be among the richest places on Earth for
plants and animals. Humans have degraded many of the natural
shrubland regions by burning and overgrazing, activities that
have also led to the loss of valuable plant species.
The extinction of land
plants is contributing to the loss
of important genes for crops as well as new sources of medicines
and pharmaceutical products. The Atlas suggests that we are
losing one important new drug every two years because of the
extinction of plants and animals and yet less than 1 per cent
of the world's estimated 250,000 tropical plants has been
screened for potential pharmaceuticals.
Klaus Toepfer, executive
director of the United Nations
Environment Programme, said this loss of new sources of
drugs could be arrested if local people were encouraged
to take part in their preservation. "We must address
the issue of genetic resource sharing by giving developing
countries, where the majority of biodiversity remains,
an economic incentive to protect wildlife by paying them
properly for the plants and animals whose genes get used
in new drugs or crops," Mr Toepfer said.
Oceans
Human activities, directly
or indirectly, are now the primary
cause of changes to the makeup of the animals and plants in
the oceans.
About one third of
the human population lives within the
coastal zone - within 60km (37.3 miles) of the sea - and
this proportion is forecast to rise this century. "Pressures
exerted by the human population on the marine biosphere are
substantial and increasing," the Atlas says.
In many ways the Earth
is a water world, with oceans
covering 71 per cent of the surface. Furthermore, the
average depth of the oceans is about four times the average
elevation of the land, making it even bigger in terms of
total volume.
Despite its size, however,
the marine environment produces
about the same amount of organic matter as the land because
photosynthesis - the process on which all life ultimately
depends for energy - is limited to the upper layers of the
ocean.
Some parts of the oceans
are highly productive whereas others
are virtually barren. The diversity of marine species is not
as great as the diversity of terrestrial species, perhaps
because the marine environment is more uniform and continuous.
The seas are the richest
source of wild protein in the
human diet. It comes in the form of fish, mollusks
(e.g. mussels) and crustaceans (e.g. shrimps), but over
the past decade this supply has begun to dwindle. Over
the past 50 years the world catch has grown fivefold but
since the 1990s it has declined substantially despite
increased efforts to find fresh stocks of fish. More
than half of the world's main fisheries are suffering
from overfishing.
The Atlas identifies
18 marine "hotspots" in the world
that are rich in endemic species. Many of these are coral
reefs - often described as the tropical rainforests of the
sea - which harbor some of the most diverse wildlife
communities on Earth.
Although marine algae,
microscopic plants, provide most of
the energy needed to support life in the sea, other plants
also play a role. Among the most important of these are the
sea grasses. As with the coral reefs, some of the most
important sea grass beds are being lost. Since the 1930s,
sea grass beds along the Atlantic coasts of America and
Europe have been lost to a marine slime mould possibly
linked with toxic pollution and trawling.
In addition to fish,
the oceans also support other
important groups of animals, such as sea mammals and
sea birds, which have all suffered through hunting and
modern fishing methods.
Lakes and rivers
Inland waters constitute
a tiny fraction of the Earth's
total surface area yet they are vital for human settlements
and have consequently borne the brunt of the worst excesses
of man's activity, often by becoming a dumping ground for
human waste. Only 2.5 per cent of the world's water is
freshwater and a large proportion of this, some 69 per
cent, is locked up in the form of ice and permanent snow.
Much of the rest is in subterranean aquifers, which means
that only 0.3 per cent of the world's freshwater resides
in lakes and rivers.
While the amount of
available freshwater is limited,
demands on it continue to grow as the human population
expands. Agriculture consumes about 70 per cent of all
water drawn from the world's lakes, rivers and aquifers,
but much of this soaks away or evaporates before it reaches
the intended crop.
Freshwater, and the
lakes and rivers that provide it,
being a vital resource for human survival, come under
conflicting demands with increasingly adverse consequences
for their biodiversity, according to the World Atlas on
Biodiversity. "There are indications that, overall, a higher
proportion of inland water species are in decline than marine
or terrestrial forms," it says.
Animals are particularly
diverse in inland waters. Freshwater
fish, for instance, are more diverse than their marine cousins,
probably because of the isolated nature of rivers and lakes.
Scientists estimate there is one fish species for every 15 cubic
kilometers of freshwater compared with one fish species for
every 100,000 cubic kilometers of seawater.
About 40 per cent of
known fish species occur in freshwater,
with about 10,000 species confined solely to lakes and rivers.
Inland waters support a large number of wildlife species,
wading birds, freshwater reptiles and mammals, despite
accounting for such a small proportion of the Earth's
surface area.
Freshwater, which links
the land with the sea, typifies
the complex interactions that characterize the study of
biodiversity. Affecting the land can have an impact on
lakes and rivers, which in turn can change the oceans.
Mark Collins, the director
of the United Nations Environment
Programme World Conservation Monitoring Center in Cambridge,
emphasized at yesterday's launch of the Atlas that life on
Earth cannot be considered in isolation. He cited the case
of land degradation on the slopes of Mount Kenya, which is
not just affecting the species on the mountain. People downstream
from the river formed by Mount Kenya now have to contend with
flash floods and droughts caused by a sporadic flow of water
resulting from deforestation.
"Biodiversity
is not just about species. It's about
how they interact with one another," Dr Collins said.
"The conservation of the resources of the natural world
is not a luxury any more but essential to the quality of
human life."
© 2002 Independent
Digital (UK) Ltd
###
