The state of the world’s oceans continues to deteriorate. As new threats to the health and viability of the oceans
emerge, most of the problems identified decades ago have still not been solved and many have become worse,
according to a study carried out in 2001 by the United Nations Joint Group of Experts on the Scientific Aspects
of Marine Environmental Protection. At risk are the vast resources of the oceans and the many economic benefits that humanity derives from them, estimated to be about $7 trillion per year.
Coastal areas — the most productive marine environments — are the most affected. Currently more than
half of the world’s population lives within 100 kilometers of the coast, with two thirds of all cities with over
2.5 million inhabitants. By 2025, it is expected that 75 per cent of the world’s population will live in coastal
The large-scale movements of populations to coastal areas have been coupled with a significant increase in
economic activity and industrialization along the coastline — such as oil and gas exploration, mining, fish farming, tourism, development of ports, marinas and coastal defenses — putting enormous pressure on coastal areas.
Pollution, the overexploitation of marine resources and the destruction of marine environments are the
greatest threats to the oceans. About 80 per cent of all pollution entering the oceans comes from land-based
sources: this includes both land-based discharges and discharges through the atmosphere. The rest is due to
maritime transportation, dumping and offshore production.
Pollution from Land-based Activities
While the amount of some pollutants discharged into the seas has been reduced, and some forms of pollution
are now thought to pose less of a threat than before, the amount of waste — municipal, industrial and agricultural — introduced into the sea is growing worldwide. These pollutants include sewage, persistent organic
pollutants, radioactive substances, heavy metals, oils, nutrients and litter. Also growing is the use of pesticides,
fertilizers and other agrochemicals — all substances that are washed or blown off the land into the oceans.
Sewage, or improperly treated domestic wastewater, poses one of the gravest hazards to coastal environments
worldwide. The enormous inputs of nutrients that sewage introduces into the marine environment can destroy
the very sensitive and fertile environments of coral reefs, lagoons and seagrass beds. It leads to changes in
species diversity and causes excessive growth of algae. It also causes extensive economic losses by ruining
large areas used for fisheries, recreation and tourism.
Human health is also threatened by pollution from sewage, which causes frequent outbreaks of gastrointestinal diseases such as cholera, typhoid and infectious hepatitis, which in turn has precipitated a health crisis
with massive global implications. Bathing in polluted seas is estimated to cause some 250 million cases of
gastroenteritis and upper respiratory disease every year, costing societies worldwide about $1.6 billion per year,
according to a recent study sponsored by the World Health Organization (WHO) and the United Nations Joint
Group of Experts on the Scientific Aspects of Marine Environmental Protection. The toll from consuming contaminated shellfish is even greater. The same study estimates that eating uncooked sewage-contaminated
shellfish causes some 2.5 million cases of infectious hepatitis each year, at a cost of some $10 billion annually.
Sewage also introduces significant amounts of plastics and other marine debris to coastal waters, threatening
marine life through entanglement, suffocation and ingestion. Plastic bags are often mistaken by sea turtles for
jellyfish and eaten — blocking their digestive systems and potentially killing them. Fishing lines and nets, sixpack rings, ropes and other litter can wrap around fins, flippers and limbs, resulting in drowning or amputation.
Some debris can keep killing for decades.
To address problems caused by pollution from land-based activities, more than 100 countries in 1995 adopted two
international documents: the Washington Declaration on the Protection of the Marine Environment from Land-based
Activities, and the Global Programme of Action for the Protection of the Marine Environment from Land-based Activities
(GPA). The latter addresses the impacts of land-based activities on the marine and coastal environments, covering
issues such as contaminants, the physical alteration of marine and coastal environments, sources of pollution, the protection of habitats critical for endangered species, and the protection of ecosystems such as breeding and feeding grounds.
In addition, the World Bank, through the Global Environment Facility (GEF), has in place programmes to reduce
pollution due to non-treated sewage, as well as initiatives to reduce nitrogen pollution.
Pollution from Ships
Threats to the marine environment from shipping activities, while not as prevalent as pollution originating on land, can
also arise from accidents, operational discharges, and physical damage to marine habitats.
While in tonnage terms the main pollutant entering the marine environment due to shipping operations is oil, the
greatest threat to the marine environment stemming from shipping activities arises from the introduction of harmful
alien species into new environments through ships’ ballast water. It is estimated that 3,000 species of animals and
plants are transported every day around the world in the ballast water of ships or in their hulls.
In response to these threats, the International Maritime Organization (IMO) — a United Nations specialized agency
— has developed a number of international rules and standards, such as the International Convention for the Prevention
of Pollution from Ships. In 2001, to address the use of toxic anti-fouling paints on ships hulls, the IMO adopted the
Convention on the Control of Harmful Anti-fouling Systems on Ships. Regulations for ballast water management, to
prevent the transfer of harmful aquatic organisms in ballast water, are under development.
Until recently, ocean dumping was an accepted method of waste disposal in many regions of the world. But in recent
years, dumping of substances considered to be threats to the marine environment, as well as incineration at sea, have
been phased out as a result of the establishment of international and national norms that promote more environmentally
friendly disposal methods. These changes have substantially reduced the amount of pollutants dumped into the oceans.
The Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (the London
Convention), adopted in 1972, and its 1996 Protocols, contain the key international rules and standards dealing with
dumping. Other instruments have also been adopted at the regional level.
The United Nations Convention on the Law of the Sea
The Convention on the Law of the Sea assigns the fundamental obligation and responsibility for protecting and preserving the marine environment to States, and requires them to adopt and enforce national laws and international standards
to prevent, reduce and control ocean pollution.
A growing number of detailed international agreements on the protection of the marine environment, as well as the
utilization, conservation and management of marine resources, have been adopted under the unifying framework of the
Convention. One of the most significant is Chapter 17 of Agenda 21, negotiated during the 1992 United Nations
Conference on Environment and Development (Earth Summit) as a complement to the Convention. This agreement
contains a programme of action for “the protection of the oceans, all kinds of seas, including enclosed and semi-enclosed
seas, and coastal areas and the protection, rational use and development of their living resources”.
Both the Convention on the Law of the Sea and Agenda 21 embody a new understanding, recognizing that the
problems facing the marine environment are closely interrelated and cannot be tackled in isolation, but must be resolved
through integrated management of resources and environmentally sound economic development.
Some regional and subregional programmes have led to significant progress in the protection and preservation of
the marine environment. The regional approach is extremely effective, and was the basis for the development of the
UNEP Regional Seas Programme and Action Plans, as well as other regional programmes.