Jeju/Nairobi, 29 March 2004 - There are nearly 150 oxygen-starved
or “dead zones” in the world’s oceans and seas,
a new report by the United Nations Environment Programme (UNEP)
These ‘dead zones’ are linked to an excess of nutrients,
mainly nitrogen, that originate from agricultural fertilizers, vehicle
and factory emissions and wastes. Low levels of oxygen in the water
make it difficult for fish, oysters and other marine creatures to
survive as well as important habitats such as sea grass beds.
Experts claim that the number and size of deoxygenated areas is
on the rise with the total number detected rising every decade since
the 1970s. They are warning that these areas are fast becoming major
threats to fish stocks and thus to the people who depend upon fisheries
for food and livelihoods.
The issue is raised in UNEP’s first ever Global Environment
Outlook Year Book which is being launched to governments attending
the Global Ministerial Environment Forum (GMEF) taking place this
week in Jeju, Korea.
The Year Book looks at some of the environment-related milestones
of the past year both globally and regionally.
Issues covered include the coming into force of the Cartagena Protocol,
an international treaty covering trade in genetically modified organisms,
the costs of mainly weather-related natural disasters and the challenges
that remain in improving drinking water supplies for over 1 billion
The Year Book also identifies the continued ‘fertilization’
of the planet and growth of oxygen starved areas in the oceans as
a key emerging issue that governments need to urgently address.
In some parts of the world, such as large parts of Africa, nitrogen
shortages are reducing farmers’ chances of meeting food demands.
Such areas desperately need more fertilizers. However, in many other
parts of the globe, excessive use of fertilizers is contributing
to the escalating problem of dead zones.
Klaus Toepfer, UNEP’s Executive Director, said: “ Human-kind
is engaged in a gigantic, global, experiment as a result of the
inefficient and often over-use of fertilizers, the discharge of
untreated sewage and the ever rising emissions from vehicles and
factories. The nitrogen and phosphorous from these sources are being
discharged into rivers and the coastal environment or being deposited
from the atmosphere, triggering these alarming and sometimes irreversible
“Some of these so called dead zones or oxygen starved areas
are relatively small, less than one square kilometre in size, whereas
others are far larger at up to 70,000 square kilometres. What is
clear is, that unless urgent action is taken to tackle the sources
of the problem, it is likely to escalate rapidly “ he said.
“Hundreds of millions of people depend on the marine environment
for food, for their livelihoods and for their cultural fulfillment.
Reducing the impacts of agriculture, human wastes and air pollution
on the oceans and seas will be a key component in helping us to
meet the Millennium Development Goals and deliver the World Summit
on Sustainable Development’s Plan of Implementation in areas
ranging from fisheries and biodiversity loss, to sanitation and
poverty,” added Mr Toepfer.
The emergence of areas of artificially low oxygen levels can be
closely correlated with the use of synthetic fertilizers in agriculture.
Nitrogen is a main ingredient of these fertilizers.
Even when carefully managed, a lot of the fertilizer applied to
crops is left in the soil. From there it is easily washed into rivers
and subsequently to the sea.
The fertilizers, often in combination with nutrients from sewage,
and nitrogen gases from traffic and industrial fumes falling on
coastal water from the air, trigger blooms of tiny marine organisms
Their rapid growth and decomposition uses up oxygen in the sea-water
leading to depleted oxygen levels.
Sometimes the effects are mild. But sometimes they can be dramatic
with fish fleeing the ‘suffocating waters” and creatures,
like clams, lobsters, oysters, snails and other slow moving, bottom
living creatures, dying en mass.
The economic costs associated with these oxygen depleted areas
is unknown, but predicted to be significant on a global scale.
Some of the earliest recorded dead zones were in places like Chesapeake
Bay in the United States, the Baltic Sea, the Kattegat, the Black
Sea and the northern Adriatic Sea. Others have been reported in
The most well known area of depleted oxygen is in the Gulf of Mexico.
Its occurrence is directly linked to nutrients or fertilizers brought
to the Gulf by the Mississippi River.
Others have been appearing off South America, China, Japan, south
east Australia and New Zealand.
In some parts of the world, actions have been taken to reduce the
amounts of fertilizer and sewage running off the land.
An agreement for the River Rhine in Europe, in which countries
agreed to reduce by half the levels of nitrogen being discharged,
has cut by 37 per cent the quantities of nitrogen entering the North
However, there is concern that more oxygen starved areas will emerge
in coastal waters off parts of Asia, Latin America and Africa as
industrialization and more intensive agriculture increase the discharge
Experts believe that global warming, with its likely increase in
rainfall and temperatures, may aggravate the problem. Research by
a team at the College of William and Mary, Virginia Institute of
Marine Science in Gloucester Point, Virginia, whose work has contributed
to the GEO Year Book, indicates that there may be large changes
in rainfall patterns with a doubling of levels of carbon dioxide.
In some areas, this in turn could lead to a marked increase in
the levels of run-off from rivers into the seas. They calculate
that dissolved oxygen levels in the Northern Gulf of Mexico, triggered
by an increased discharge from the Mississippi river basin of 20
per cent and a climb in temperature of up to four degrees Centigrade,
could fall by 30 to 60 per cent.
Actions to reduce the threats should focus on sources of the nitrogen
overload. Numerous options are available to governments, partly
as a result of new scientific understanding as to how nitrogen ‘cascades’
through the environment.
For example, forests and grasslands have a high ability to ‘soak
up’ excess nitrogen and slow down its movement from the land
to the rivers and the seas. Planting more forests and encouraging
more grasslands in some areas of the globe might help.
Improving ‘precision agriculture’ so that less fertilizer
is wasted should be another option. Producing livestock in the regions
where most of their feed comes from could also reap benefits.
Large number of farm animals in Europe are fed on soya, produced
in North America and Latin America. Raising the animals in the soya
growing regions could reduce the exports of nitrogen to regions
like the European Union where nitrogen excess is an issue.
Other actions include more widespread use of technologies that
remove nitrogen compounds from vehicles fumes alongside the wider
uptake of alternative energy sources that are not based on burning
Better treatment of sewage, both by high tech systems such as water
treatment works and low tech systems, such as wetlands and reed
bed networks, will not only reduce nutrient discharges to coastal
waters, but will help the world meet the water and sanitation aims
in the Millennium Development Goals.
Notes to Editors
The UNEP Global Environment Outlook (GEO) Year Book 2003 is a new
accompaniment to the successful Global Environment Outlook (GEO).
The third in this series was published in 2002.
The impact of fertilizers and nutrients on the health of the planet
was flagged up in GEO-2000 but, as the new Year Book shows, little
action to address the threat has been taken globally.
The Year Book, including the report and graphics on ‘Dead
Zones’, is available at www.unep.org/geo/yearbook/
It can be purchased at http://www.earthprint.com/go.htm?to=3348
The 8th Special Session of the UNEP Governing Council/Global Ministerial
Environment Forum will take place in Jeju from 29 March to 31 March
2004. More details are available at http://www.unep.org/GC/GCSS-VIII/index.asp
and also at http://www.2004unepkorea.org/
For More Information Please Contact Eric Falt, Spokesperson/Director
of UNEP’s Division of Communications and Public Information,
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or Nick Nuttall, UNEP Head of Media, on Tel: 254 20 623084, Mobile:
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UNEP News Release 2004/14