Oiling the oceans
The Torrey Canyon disaster – a wake-up callThe global oil industry often exacts a heavy toll from the environment. Onshore, there is the problem of soil contamination by oil from leaking pipelines. Offshore, oil spilled from damaged tankers poisons marine life, coats and clings to the feathers of seabirds, and pollutes coastlines. The problems associated with the production and transportation of crude oil became all too apparent in the 1960s and 1970s, when the first supertankers came into service, increasing the potential threat to the environment. It was then that the world witnessed its first major oil spills, often affecting many thousands of people. The first of these disasters occurred in 1967, when the tanker Torrey Canyon, which was carrying 119,000 tonnes of crude oil, hit rocks and was wrecked near the Isles of Scilly off southwest England. The oil formed a slick measuring some 1000 square kilometres and caused massive pollution of coastlines around Cornwall, Guernsey in the Channel Islands, and France.
- 1.30 > In March 1967, the Torrey Canyon hit rocks off the south coast of England. The oil from the stricken tanker caused massive pollution along the coast of southern England, and within three weeks had drifted as far as Brittany and Normandy in France. 1.31 > The Royal Air Force dropped bombs in an attempt to sink the vessel and its remaining cargo, igniting the oil slick. The pall of smoke from the burning oil was visible more than 60 miles away.
Oil pollution – an insidious threatTanker disasters and oil rig explosions still occur from time to time; one example was the Deepwater Horizon incident in spring 2010, in which a vast quantity of oil was released into the environment in a very short period of time. Yet in reality, this kind of spectacular disaster accounts for only a small percentage of global marine oil pollution. Most of the oil travels along less obvious pathways. Of the estimated one million tonnes of oil entering the marine environment annually, around 5 per cent comes from natural sources. In the Gulf of Mexico, for example, crude oil seeps naturally out of underground fissures and cracks and rises from the reservoirs to the ocean floor. Elsewhere, as in the Caspian region, large amounts of crude oil erupt from underground reservoirs into the water via mud volcanoes. These are not true volcanoes but mounds on the seabed. They contain watery sediment which heats up deep underground, causing it to rise. In some cases, it transports oil from nearby reservoirs upwards as well. Oil tanker disasters account for around 10 per cent of global marine oil pollution. Around 35 per cent comes from regular shipping operations; this includes oil released during incidents involving all other types of vessel, as well as oil from illegal tank cleaning. The largest share, amounting to 45 per cent, comes from inputs from municipal and industrial effluents and from routine oil rig operations, together with a small amount from volatile oil constituents which are emitted into the atmosphere during various types of onshore burning processes and then enter the water. A further 5 per cent comes from undefined sources. This includes smaller inputs into the sea by polluters who go undetected. These percentages naturally do not apply to 2010 and other years in which major oil spills have occurred. The Deepwater Horizon disaster alone released around 700,000 tonnes of oil into the sea – more than two-thirds the amount that would normally enter the marine environment over the course of an entire year.
Progress on combating pollutionThe good news is that the number of oil spills from tanker incidents or caused by technical failures or explosions on tankers has fallen dramatically in recent decades, despite steady growth in the seaborne oil trade. In the 1970s, there were between 50 and 100 large oil spills a year, compared with fewer than 20 a year since the start of the millennium. The statistics cover oil spills above seven tonnes; there is no systematic collection of data on smaller incidents.
Consistent with the reduction in the number of oil spills from tankers, the volume of oil spilled has also gradually decreased. Of the total volume of oil spilled from tankers between 1970 and 2009, only around 3.7 per cent was spilled after 2000. The largest amount of oil entered the marine environment in the 1970s – around 15 times more than in 2000 to 2009.
According to experts, this decrease is primarily due to the international conventions and regulations to protect the marine environment, which were progressively introduced after the various oil disasters. One of the most important is the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78), which since 1983 has formed the basis for the designation of marine protected areas where tanker traffic is wholly or partly restricted. The Convention brought the number of oil tanker disasters down during the 1980s. MARPOL 73/78 also paved the way for the introduction of double hull tankers. It is now mandatory for all new tankers to be fitted with a double hull, so that if a vessel is involved in a collision which penetrates the outer hull, the tanks inside generally remain intact.
- 1.33 > Although seaborne oil trade has increased since the 1970s, the number of tanker spills has decreased. The statistics cover oil spills above seven tonnes.
- 1.40 > The Deepwater Horizon explosion is the largest oil spill in the oil industry’s history. The map shows the location of the world’s 10 largest oil spills and other incidents.
- 1.41 > Of the total volume of oil lost as a result of tanker incidents around the world from 1970 to 2009, the largest amount was spilled in the 1970s and the smallest during the period 2000 to 2009.
- Another milestone was the adoption of the Oil Pollution Act (OPA) in the United States, which was signed into law in 1990 – one year after the Exxon Valdez ran aground in Prince William Sound in the Gulf of Alaska in March 1989, spilling crude oil along a 2000 kilometres stretch of coastline which included several bird sanctuaries and nature reserves. Even today, some areas are still contaminated with oil residues, which have biodegraded very slowly in Alaska’s cold temperatures. As a result of this disaster, the US took the initiative on the protection of the marine environment and adopted legislation – the OPA – to protect its territorial waters, ahead of other countries. Under the legislation, ships entering US waters are regularly inspected, primarily to ensure that they comply with safety standards and regulations pertaining to the adequacy of qualifications and training of crew members. The OPA also established a double hull requirement for tanker vessels operating in US waters. Much of the OPA’s content has been incorporated into international regulations as well, including provisions on reliable radio technology for onboard communication and a vessel identification system to enable shipping control authorities to check a ship’s course and position at any time
. Following a comprehensive analysis of the tanker incidents that occurred in the 1980s, the International Maritime Organization (IMO) in London adopted the International Management Code for the Safe Operation of Ships and for Pollution Prevention (International Safety Management Code, or ISM Code) in 1994. The development of the ISM Code was based on the recognition that a number of serious incidents had manifestly been caused by human errors by crew members. The primary objective of the ISM Code is therefore to ensure the safe operation of vessels and thus protect persons on board ships and avoid damage to the environment. According to the ISM Code, entities responsible for the operation of ships must ensure, among other things, that each ship is manned with qualified, certified and medically fit seafarers, who must undergo regular training to prepare them for emergencies, the aim being to prevent incidents in future.
Joint action – more effective than going it aloneDespite the existence of these agreements, an effective cross-border response to marine pollution incidents involving oil was lacking for some time. Granted, Belgium, Denmark, France, Germany, the Netherlands, Norway, Sweden and the United Kingdom signed the Agreement for cooperation in dealing with pollution of the North Sea by oil and other harmful substances (Bonn Agreement) in Bonn in 1969, just two years after the Torrey Canyon disaster, with the accession of the European Union and other European countries following in 1983. However, there was an ongoing lack of well-coordinated contingency plans for a systematic response to major oil spills, and in many cases, the division of responsibilities remained unclear until only a few years ago.
The Pallas incident is a good example. The cargo vessel Pallas caught fire in the North Sea in 1998. Danish and German rescue teams evacuated the crew, but left the abandoned vessel with no one at the helm in rough weather. The ship drifted out of Danish into German territorial waters, but the German authorities were unable to agree which agency was responsible for the vessel. The Pallas finally beached on a sandbank in Germany’s Wadden Sea. Fortunately, only around 90 tonnes of oil were lost, but countless seabirds were oiled and several square kilometres of the Wadden Sea – an ecosystem extremely sensitive to oil pollution – were contaminated. As a result of the incident, Germany set up the Central Command for Maritime Emergencies (CCME) (Havariekommando), which is responsible for mounting an oil spill and marine pollution response and for fire fighting at sea. The CCME also directs the deployment of large emergency towing vessels, which have been stationed along the North Sea and Baltic Sea coasts in recent years. These powerful vessels are used to tow disabled ships into deeper waters or to a safe haven, thus preventing them from running aground and leaking oil, as occurred with the Pallas.
International cooperation is more effective nowadays as well. Various contingency plans are now in place, backed up by international exercises to practise the oil spill response. These take place every year over several days and involve as many as 50 vessels from various countries. Under the Bonn Agreement, for example, ships from all the signatory countries come together for the joint Bonnex exercise in the North Sea.
- The Baltic Sea is protected under the Helsinki Convention, which entered into force in 2000. Under this Convention too, all the states bordering the Baltic Sea hold an oil spill response exercise, known as Balex (Baltic Exercise), which takes place in summer every year in a different area of the Baltic Sea. The contingency plans include provisions stating how information is to be passed on, e.g. by email, radio or fax, and who is responsible for decision-making. They also specify which ships are to be deployed and when.
Analogous to the agreements on the North Sea and the Baltic Sea, the Barcelona Convention deals with the protection of the Mediterranean Sea. The Barcelona Convention was signed in 1976. The Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea (REMPEC) was set up in Malta the same year and is responsible for dealing not only with oil-related incidents but also with other forms of pollution. One of its primary objectives was to develop and strengthen the technical capacities of coastal states in the Mediterranean region to combat oil pollution. REMPEC also organizes exercises, albeit less regularly than in northern Europe. In most cases, the exercises do not involve all the Mediterranean coastal states but only those from a specific area of the Mediterranean. Workshops are also organized, but again, these generally target coastal states from a specific Mediterranean region, usually the European or Arab countries.
As the history of oil spills shows, many of the measures described were adopted only after serious incidents had occurred. This applies to the oil spill response in South East Asia as well. On 7 December 2007, a drifting crane barge rammed the tanker Hebei Spirit close to Taeanhaean National Park in South Korea. The tanker was holed and lost 11,000 tonnes of crude oil. Within a matter of hours, the oil slick was many kilometres long. It polluted the tourist beaches and contaminated mussel farms. According to experts, the oil spill caused damage amounting to around 250 million Euros. Back in 1994, South Korea and its neighbours China, Japan and Russia had signed an agreement – the Northwest Pacific Action Plan (NOWPAP) – to protect this sea area, but a joint contingency plan was still lacking. Just 11 days after the Hebei Spirit incident, nations took action: at South Korea’s behest, the countries concerned adopted the Regional Oil Spill Contingency Plan. Since then, the countries have held various joint oil spill exercises. The most recent, in May 2012, was organized jointly by China and South Korea and took place off the South Korean coast.
- Some of the oil-exporting nations in the developing world have yet to achieve the same level of progress. This applies, for example, to the West and Central African countries. Although many of these countries have produced contingency plans in recent years, there is often a lack of proper coordination and technical equipment. According to an international study, even the major oil-exporting nations – Cameroon, Ghana, Nigeria and Angola – lack specialized oil spill response vessels. Cameroon and Ghana only have small towing vessels and a number of booms available for use in emergencies, and Angola and Nigeria have no inventory of oil spill response equipment at all. According to the relevant contingency plans, this is to be supplied by the oil companies, if required. This includes coastal cleanup equipment, such as specialized tanker lorries with suction gear. In the event of an incident, dispersant spraying systems are to be deployed from chartered ships or heli-
The study identifies a further problem: although many of the West and Central African countries have set up emergency telephone numbers, they are often not functional. Document distribution and information exchange between the relevant authorities and institutions are clearly dysfunctional, too, and information is sometimes lacking in detail. This makes it more difficult to ensure good coordination between all the various agencies in the event of an incident. In other countries in West and Central Africa, the situation is even more sobering. Six countries have no contingency plans at all, while others lack the fundamental elements that should be a given in any oil spill response, such as a central emergency telephone number or radio frequency for reporting and alerting. It is debatable, therefore, whether these nations would be able to mount an adequate response to a major oil spill unaided.
Aerial surveillance stops pollutersAs regards the ongoing but less visible oil pollution of the marine environment by ships, the situation has improved in various regions of the world. Again, the MARPOL Convention has made a contribution here. MARPOL defines seven of the world’s sea areas as “special areas” which are provided with a higher level of protection than other areas of the sea. Only tankers which comply with specific safety standards are permitted to transit these sea areas; these include limits on the size of tanks on oil tankers in order to minimize the amount of oil that could escape in the event of an incident causing damage to the hull. The special areas are:
- the Antarctic Area (since 1992);
- the “Gulfs” area (since 2008);
- the Mediterranean Sea (since 1983);
- the North West European Waters/North Sea (since 1999);
- the Baltic Sea (since 1983);
- the Black Sea (since 1983);
- the Southern South African Waters (since 2008).
- 1.43 > In the Baltic Sea, the number of observed oil slicks has decreased by almost three quarters. Experts attribute the improvement in the situation in Northern European waters to the deterrent effect of aerial surveillance, among other things.
- In several of these special areas, such as the Mediterranean, the North Sea and the Baltic Sea, aerial surveillance has been in operation for many years. As oil spills can be easily detected by aircraft fitted with special camera systems, vessels whose crews have cleaned out the tanks at sea or discharged oil can be identified very quickly. As causing pollution in the special areas results in criminal prosecution, aerial surveillance has had a deterrent effect, resulting in a noticeable decrease in the number of illegal discharges. The black lumps of oil which often washed up on beaches in the 1980s are rarely seen in Western Europe nowadays. Furthermore, for some years now, efforts to detect oil pollution have been supported by satellite data. However, satellite images can sometimes be misleading: algal blooms are occasionally misinterpreted as oil slicks, for example. Many of the relevant authorities therefore generally deploy aircraft to check out pollution alerts. The benefit of satellite surveillance from space, however, is that it provides a broad overview of large areas of the sea. In China and some European countries, various research projects are currently under way to improve data evaluation. A joint programme has also been launched in Norway, involving the military, environmental agencies, meteorological institutions and universities, to investigate to what extent satellite data can be used in the surveillance of Norway’s territorial waters in future.
Despite the clearly positive trend in Europe, the number of oil spills here is still relatively high compared with other regions of the world. This is due to the high volume of merchant shipping in this region, particularly in the English Channel, which frequently causes pollution incidents. Only Asia has more oil spills, mainly in the Strait of Malacca between Indonesia and Singapore. In Chinese waters, the number of oil pollution incidents has actually increased in recent years, due to the country’s economic growth and burgeoning exports and imports, which have resulted in a substantial increase in shipping. In the US, on the other hand, the amount of oil entering the environment has decreased dramatically since 1990. US authorities attribute this reduction primarily to the stringent provisions of the Oil Pollution Act.
Constraints on the oil spill responseWhen crude oil spills into water, the oil spreads out and forms a thin film that floats on the surface of the water. Depending on the temperature, the volatile organic compounds (VOCs) in the oil, such as benzene, evaporate within a matter of hours. These can constitute as much as 30 to 50 per cent of the oil’s original mass.
Oxygen and ultraviolet (UV) radiation from the sun also react with the oil, changing its chemical properties. Finally, within a few days, a dense and viscous oil slick forms, mainly consisting of large hydrocarbon molecules. During the first few hours or even during the first few weeks, the oil is modified by the following chemical and physical processes:
- evaporation of volatile organic compounds (VOCs);
- spreading of the spilled oil in large oil slicks drifting on the surface waters;
- formation of dispersions (small oil droplets in the water column) and emulsions (larger droplets of oil-in-water or water-in-oil);
- photooxidation (molecular changes to the oil constituents caused by natural sunlight) and solution.
- 1.44 > Surfactants are deployed in the oil spill response. Their molecules have a hydrophilic end, which binds to water, and a lipophilic end, which binds to oil. They surround small oil droplets and break up larger quantities of oil.
- Once the chemical and physical properties of the oil have been modified, it becomes almost impossible for oil spill control vessels to skim the oil off the surface of the water. Some of the oil sinks to the sea floor. For that reason, it is particularly important to mount a rapid response whenever oil pollution incidents occur.
In Western Europe, the oil spill response relies primarily on specialized vessels equipped with devices known as sweeping arms. These skim the oil/water mixture off the surface of the water and transfer it to storage tanks on board. Until the 1990s, these vessels had very limited capacity, so the tanks filled up very quickly. Over the past 15 years or so, however, many ships have been fitted with oil separators which remove the oil from the water. The clean water is then pumped overboard. This has increased the vessels’ response capacities. However, there are constraints on the use of sweeping arms, as the slender devices cannot be deployed in high winds or heavy swell. German researchers have therefore been working on the development of a sea swell-independent oil skimmer (SOS) for some years. Suspended between the hulls of a catamaran, the SOS will have the ability to operate in storms and rough seas, moving into an oil slick and siphoning the oil film off the water.
Dispersants can also be used to prevent the formation of an oil slick. These substances break up oil slicks in accordance with the same principle by which washing-up liquid dissolves residual grease from food. Dispersants contain surfactants, whose molecules have a lipophilic and a hydrophilic end. They work by bonding to the oil molecules and separating them from water molecules – thus breaking up an oil slick into small droplets, which they then surround and isolate. Experts call these droplets “micelles”. The advantage is that bacteria can break down the numerous small micelles much more easily than a large slick. Chemical dispersants were used in very large quantities after the Deepwater Horizon explosion. They were sprayed on the surface from aircraft but were also used deep underwater on the sea floor, where they were mixed with the oil emerging from the well. According to critics, the use of dispersants is problematical because some surfactants are toxic. Proponents of dispersant use, on the other hand, argue that surfactants are very heavily diluted in water and therefore pose no threat to marine life. For the advocates of dispersant use in oil-spill response, the benefits far outweigh the potential environmental risks.
There are limits, however, to dispersant use as well. It is almost impossible to spray them on target during storms, when aircraft are often grounded anyway.
Even today, the response to major oil spills can never be entirely satisfactory. In the view of oil spill response experts, prevention is therefore the best strategy. Seaways with modern traffic control systems and well-trained maritime pilots who can play a monitoring role are part of a preventive approach. Ship owners must also ensure that their vessels are seaworthy and equipped with appropriate technology and that crew members are properly qualified.
- 1.45 > During an oil spill exercise off Helsinki, the multipurpose vessel Hylje uses a sweeping arm to capture foam that is specially designed to simulate an oil slick.
Coasts at riskOil is a naturally occurring mix of hydrocarbons which is broken down by bacteria in a biological process. These bacteria are particularly active under the following conditions:
- high temperatures, promoting bacterial activity;
- a large surface area (if necessary, the surface area of the slick can be increased through the use of dispersants which promote the formation of dispersions);
- a good oxygen supply;
- a good supply of other key nutrients;
- a low number of predator organisms which would reduce the number of bacteria.
- 1.46 > For a month after the Deepwater Horizon disaster, droplets of oil accumulated along the beach at Grand Terre Island on the Louisiana coast.
- Oil pollution is particularly problematical in mangrove forests, which are unique, species-rich habitats. Covered in oil, the vegetation dies, destroying the habitats of many other species of flora and fauna. What’s more, oil penetrates to great depths in the soft sediments of mangrove forests and remains in the ground for long periods. Salt marshes are similarly affected: here too, the vegetation forms characteristic and rare habitats for very well-adapted flora and fauna. These ecosystems are lost when oil kills off the vegetation.
Oil pollution also poses a particular threat to soft substrates and sandbanks, such as those found in the Wadden Sea on the North Sea coast. Here, most organisms live in or on the sea floor and are therefore particularly at risk from oil slicks. Mangroves, salt marshes and soft substrates take at least two years, and sometimes more than 20 years, to recover from oil pollution. For such sensitive habitats, even smaller oil spills can become a very serious problem.
According to environmentalists, there is a special threat to the Arctic waters, due to the Arctic nations’ plans to carry out oil drilling here in future. Russia and the US, in particular, have ambitions to develop the oil and gas reserves in their northern regions. But developing these reserves is likely to pose major challenges. Drift ice could destroy drilling and production rigs, and tankers could be wrecked in the ice.
When Shell Oil Company began test drilling in Alaska in 2012, for the first time in 20 years, it faced massive protests from environmental groups. They warned about the particular risks posed by drilling in sea ice, the possibility of tanker incidents, and the likely impacts of an oil disaster.
- Much of the Arctic is still a natural habitat with unique and largely untouched ecosystems, which could be massively damaged by oil – not least because an effective oil spill response is almost impossible to mount in an icy environment, and because the oil would biodegrade very slowly in the region’s very cold temperatures. And indeed, the drilling programme was beset by problems. Equipment was damaged by the ice, and a drilling rig, Kulluk, ran aground. After the project came under severe criticism in an official report in the US, Shell cancelled its 2013 drilling programme. Among other things, the report drew attention to the inadequate safety standards for Arctic drilling.
In spring 2013, Shell signed a memorandum on cooperation with the Russian energy company Gazprom, focusing on hydrocarbon exploration and development on Russia’s Arctic shelf. Critics fear that safety standards will be even lower here, and are warning about the risk of a major oil disaster. It is difficult to predict the future of oil exploration and development in the Arctic regions of the US, where industry and environmental organizations are currently at loggerheads over the level of protection that should be afforded to the Arctic. Industry associations warn that excessively stringent safety regulations will make the development of an oil industry economically non-viable, whereas environmental groups are calling for a total ban on oil production in the Arctic. Experts take the view that oil companies in the US will continue to have their sights firmly fixed on the Arctic’s oil reserves, and that US companies will step up their efforts to exploit these resources as soon as other countries, but particularly Russia, discover major oil reserves in their exclusive economic zones.
Should coasts be protected or abandoned?Major incidents often result in the formation of massive oil slicks, extending for hundreds of kilometres. In these situations, it is impossible to protect the entire coastline. The response must therefore focus on the most important and sensitive stretches of shoreline. Protecting nature reserves or habitats for rare fauna and flora is regarded as a priority, and economically important zones, such as aquaculture facilities, should also take precedence. Sensitivity maps now exist for many regions of the world. They provide detailed information about the oil pollution sensitivity of various stretches of coastline, and identify the species of flora and fauna occurring there. Key factors are species’ rarity, the level of risk posed to them by oil pollution, and how likely it is that species would die out locally in the event of an oil pollution incident. Often, it is not the seabirds or marine mammals which are most at risk, but rare species of plant or insect. All this information is also used to prepare contingency plans. Response teams are now supported by computer programs which provide access to databases containing sensitivity data. This information can be linked with up-to-date meteorological data to calculate the route of the oil slick and the extent to which important areas will be affected. In this way, response teams can direct oil spill response vessels to areas in particular need of protection or ensure that booms are set up to defend them.
- 1.47 > Seabirds are among the most obvious victims of oil spills. This heron was completely coated in oil from Deepwater Horizon.
The effects of oil on flora and faunaAfter numerous oil pollution incidents, we now have very detailed information available about the effects of oil on flora and fauna. The most obvious effect is the damage caused to seabirds’ plumage. As a result of oil contamination, the plumage can no longer perform its vital functions of repelling water and providing thermal insulation. As a result, the bird loses body heat and dies. A similar effect can be observed in marine mammals, such as otters, which can die of cold if their fur is coated with oil. Furthermore, birds and mammals often ingest oil when they attempt to clean their oil-coated feathers or fur, and this can poison them. Fish absorb toxic hydrocarbons through their skin and gills. In plants, oil contamination interrupts gas exchange through the leaves and nutrient transfer by the roots, which causes the plant to die.
Filter feeders such as mussels and other organisms often ingest oil along with their food. The toxic hydrocarbons in the oil and the clogging up of their internal filtration systems generally kill them very quickly. If the mussels survive, the toxins can be passed along the food chain when the contaminated mussels are eaten. The effects of the toxic hydrocarbons vary from species to species. Experiments with crab or mussels show that it is mainly their metabolic processes and growth which are impaired. In other organisms, reproduction is adversely affected. Poisoning by oil can cause genetic damage: in herring, for example, numerous freshly hatched progeny were malformed. Furthermore, many marine fauna lose their sense of direction, as many of them use very fine concentrations of certain substances in the water as a means of finding their way around their environment. This is disrupted by certain hydrocarbons, making it more difficult them to forage or identify partners for reproduction.