9 biggest and worst oil spills of all time

Climate change is not the only cost of extracting crude oil. Find out about the biggest and worst oil spills of all time.
Christopher McFadden
Deepwater Horizon Oil Spill, Gulf of Mexico.
Deepwater Horizon Oil Spill, Gulf of Mexico.

Wikimedia Commons 

  • Oil is the literal lifeblood of many modern economies.
  • Every year somewhere in the order of 90 million barrels of oil are produced each day, and pipes and ships transport this to all four corners of the world.
  • While most of the time, this happens without incident, inevitably, accidents do happen.

Our modern world depends significantly on how crude oil and its derivatives are found, refined, and shipped. Whether they be used to run our cars, planes, ships, and trains or produce the capsules we need to take our daily vitamin supplements, the modern world would be a very different place without crude oil.

While this process is now very mature and usually safe, there have been times in the past when accidents (avoidable or not) have happened and released millions of tons of black gold into the environment with devastating impacts.

But which were the worst of all time? Let's take a look.

Why is it an oil spill?

An oil spill is a type of pollution that occurs when a liquid hydrocarbon from petroleum is released into the environment, usually the ocean. Oil releases into the sea or coastal waterways are considered marine oil spills. However, land-based spills are also possible.

Oil spills can be accidental or, in some rare instances, intentional.

9 biggest and worst oil spills of all time
Oil spills are some of the worst ecological disasters.

Oil spills can result from crude oil discharges from tankers, offshore platforms, drilling rigs, and wells, as well as refined petroleum products (like gasoline and diesel) and their byproducts, heavier fuels used by big ships like bunker fuel, or the spill of any oily waste or garbage.

Although catastrophes involving tankers, barges, pipelines, refineries, drilling rigs, and storage facilities are the most common cause of oil spills in rivers, bays, and the ocean, they can also include recreational boats and marinas.

Spills may result from people making mistakes or acting carelessly, malfunctioning equipment, hurricanes, storm surges, severe winds, terrorist attacks, acts of war, vandalism, or illegal dumping.

Most oils float on saltwater in the oceans or freshwater from rivers and lakes. A thin oil slick typically forms when oil spreads quickly across the water's surface. The oil slick gradually thins as it spreads, eventually reducing to a very thin sheen that frequently resembles a rainbow. (In exceptional instances, hefty oil may occasionally sink.)

Oil spills can be hazardous to marine mammals, fish, shellfish, birds, turtles, and mammals, depending on the situation. Fur-bearing mammals, like sea otters, become coated in oil and lose their capacity to insulate, while birds' feathers lose their ability to repel water, leaving them vulnerable to the weather and often unable to fly. Many animals, including birds, try to clean themselves of the oil or consume oily prey, which causes them to ingest the poison.

Oil can also be digested by fish and shellfish, which may alter their ability to reproduce, grow, or even cause their demise. Commercially significant species, including swordfish, tuna, mahi-mahi, grouper, oysters, and shrimp, might also see population losses or become too contaminated to be fished and consumed by humans.

Numerous birds, fish, mammals, reptiles, corals, and other animals and plants may also be killed or wounded depending on the location and timing of the spill.

Why are oil spills so bad for the environment?

According to some sources, with an annual average of about 1.8 significant accidents, the global trend indicates a decline in tanker oil leak incidents. Nevertheless, each spill results in hundreds of tonnes of oil entering our water.

The International Tanker Owners Pollution Federation Limited (ITOPF) reported four medium spills (7 to 700 tonnes) and two big spills (more than 700 tonnes) worldwide in 2021. And more minor oil spills also continue to pose a severe threat.

Despite the encouraging trend that these occurrences are decreasing in frequency, the magnitude of the potential effects from even a single spill should not be disregarded.

The effects of an oil spill can be severe and catastrophic, and many of these effects linger for a long time after the catastrophe itself. Many effects are immediately apparent, like the death of wildlife and beaches being soaked in oil. Still, many other effects are more subtle and challenging to treat, including the long-term direct and indirect effects on the economy and on public health.

9 biggest and worst oil spills of all time
OIl spllls are disastrous for some animals.

The first and most apparent is the impact on wildlife.

An oil spill can have a severe impact on animal populations and ecosystems on land and in the sea. If not killed outright, fish, birds, and other marine creatures can all be affected over the long term by oil spills. For instance, they might be fully engulfed in an oil slick or be covered in oil, impairing their ability to move, regulate their body temperature, and eat.

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Long after an oil spill, these effects on wildlife can still be felt; in some circumstances, they can affect the next generation.

The second is an oil spill's broader impact on the environment.

Oil spills may affect rivers, seabeds, coasts, and many other areas. Oil can disturb the natural ecosystems that make up these settings and destroy habitats, especially those that are sensitive or protected, like mangroves or coral reefs.

Another impact is an oil spill's effect on local economies.

For many years following an oil spill, the local business and economy may experience limits and physical harm, especially to the fishing and agricultural industries. A lot of people can lose their jobs or other sources of support.

While penalties imposed on the at-fault parties may assist governments and affected local communities in recovering from a spill, they are unlikely to make up for the significant immediate and long-term costs to the economy.

Oil spills also impact other areas, like tourism too.

Oil frequently spills directly impact tourist sites, and the organizations and people that rely on these places for income, due to oil washing up on beaches or hitting the coast. Additionally, there is a more subtle impact because of an adverse change in opinion about the location that may occur due to such an incident.

All of the effects above will influence nearby communities. They may have a long-term impact on how they live and work. For instance, fisheries changes can impact the ability of a community to feed itself and its financial standing. Direct exposure to the oil or downstream effects like air pollution may adversely affect nearby populations.

What's the worst oil spill in history?

The answer to this is a toss-up between two of the most famous oil spills in recent history. These are the 2010 BP Deepwater Horizon oil spill and the 1991 Persian Gulf War oil spill.

The reason for the confusion is that it is unclear just how much oil was released by the latter, with estimates of between 380 million and 580 million gallons of oil spilled. However, it is next to impossible to know for sure, but more on that later.

For this reason, we'll err on the side of caution and declare the Deepwater Horizon disaster as the worst, as we have provable values for the amount of oil released.

Also known as the "BP oil spill," it was an industrial catastrophe that started on April 20, 2010, in the Gulf of Mexico off the coast of the United States on the BP-operated Macondo Prospect.

To this day, it is still the biggest marine oil spill in the history of the petroleum industry. The federal government estimated the overall discharge to be about 210 million US gallons or roughly 795,000 m3.

The well was declared blocked on September 19, 2010, following multiple unsuccessful attempts to stop the flow. Though 2012 reports claimed the well site was still leaking.

A tremendous effort was made to stop the oil from spreading by using skimmer ships, floating booms, controlled burns, and thousands of liters of oil dispersant.

Extensive damage to marine and wildlife habitats, as well as to the vital fishing and tourism sectors in the Gulf, was recorded as a result of the spill, which lasted for months, and negative consequences from the reaction and cleanup efforts.

Throughout 2013, oil cleanup teams worked four days a week on 55 miles (89 km) of Louisiana shoreline. As far away from the Macondo site as the waters off Florida's Panhandle and Tampa Bay, where scientists believe the oil and dispersant mixture is lodged in the sand, oil was still being discovered.

According to reports from April 2013, dolphins and other marine animals continued to perish in record numbers, with young dolphins dying at a rate six times higher than usual. According to other studies, oil from the leak caused malformations in the hearts and other organs in tuna and amberjack that were expected to be lethal or, at the very least, reduce lifespans. Another study discovered that cardiotoxicity may have become common in animal species exposed to the spill.

The reasons behind the explosion and record-breaking leak became the subject of numerous investigations. The United States Government assessment, released in September 2011, blamed BP in the majority and rig operator Transocean and contractor Halliburton for the well's poor construction. A White House commission also held BP and its partners accountable for several cost-cutting measures and a weak safety system earlier in 2011.

Still, it also concluded that the spill had "systemic" root causes and might happen again without significant reform in both business practices and governmental policies.

BP and the US Department of Justice settled on federal criminal charges in November 2012. BP pleaded guilty to 11 counts of manslaughter, two misdemeanors, and a felony count of lying to the US Congress. Additionally, BP consented to four years of government oversight of its safety procedures and business conduct.

9 biggest and worst oil spills of all time
Oil spills, like the Deepwater Horizon disaster, can take years to clean up.

The Environmental Protection Agency declared BP temporarily ineligible for new contracts with the American government. BP and the Department of Justice agreed on record-breaking fines and other payments totaling $4.525 billion. As of 2018, the corporation had incurred more than $65 billion in costs related to clean-up, charges, and penalties.

A United States District Court judge found in September 2014 that the company was principally accountable for the oil leak due to BP's egregious carelessness and reckless behavior. One of the highest corporate settlements in US history, $20.8 billion in fines, was agreed upon by BP in April 2016.

What are the worst oil spills in history?

The most significant oil spills in history have resulted in the release of tens of millions of gallons of oil, contaminated fisheries, dead and injured wildlife, and decreased tourism. To this end, here are some of the worst oil spills in history.

1. The 1978 Amoco Cadiz oil

Gallons of oil spilled: Approx. 69 million

On the morning of March 16, 1978, the Amoco Cadiz, a very large crude carrier (VLCC) loaded with roughly 69 million gallons of light crude oil, grounded on shallow rocks off the coast of Brittany, France.

The ship's rudder and hydraulic system were harmed by a massive wave traversing the English Channel's choppy waters. Rescue tugs attempted to attach towlines to the Cadiz, but the task was challenging due to the rough seas.

A few hours after being fastened, the first of the towlines broke. By the time a second line could be attached, the Cadiz had already been propelled by winds and waves toward the shore of Brittany, where her stern and middle part had struck some submerged rocks.

The impact tore holes in the container tanks and hull, letting the oil out. The oil slick, which killed millions of invertebrates, including mollusks and crabs, and an estimated 20,000 birds, fouled oyster beds in the area and covered around 200 miles (321 km) of the French coast.

Owners of the Cadiz, Amoco Corporation, agreed to pay French claims $120 million in 1990 and an additional $35 million to Royal Dutch Shell, the owner of the lost oil.

2. The 1983 Castillo de Bellver oil spill

Gallons of oil spilled: Approx. 79 million (though perhaps only 53.4 million)

The Castillo de Bellver oil tanker capsized in August 1983 due to a fire on board. The ship was situated in the South Atlantic Ocean, about 70 miles (113 km) off Cape Town, South Africa coast, when the fire started on August 6th.

The ship broke into two sections and began to drift; the stern half, containing about 110,000 tonnes of oil, traveled 24 miles (38.6 km) off the coast before sinking into the deep sea.

Engineers moved the tanker's forward portion away from the coast, where they sank it with explosives. Most of the oil released at the surface was collected in the Benguela Current and taken out to sea before it dispersed, causing little environmental harm even though some of the oil slick burned during the fire.

Although many accounts state that the ship carried 79 million gallons of crude oil when the fire began, some sources estimate the tanker's load to be around 53.5 million.

3. The 1983 Nowruz oil field incidents

9 biggest and worst oil spills of all time
The Nowraz oil fields incidents of 1983 were among the worst oil spills in history.

Gallons of oil spilled: Approx. 80 million

A tanker struck an Iranian oil platform on February 10, 1983, over the Nowruz oil field in the northern Persian Gulf. The platform listed 45 degrees due to the hit, corrosion, and wave energy worked to topple the platform and break its wellhead.

Before it was finally sealed up in September 1983, the well leaked around 1,500 barrels (63,000 gallons) of oil into the Persian Gulf daily. The northern Persian Gulf was a contested battleground during the Iran-Iraq War in the early 1980s, and one month after the tanker crash, Iraqi helicopters assaulted another adjacent platform.

Before it was plugged more than two years later, the damage to this second platform caused the spill of around 733,000 barrels (or 31 million gallons) of oil into the Gulf of Mexico. Around 20 workers lost their lives while trying to cap the wells during the capping and repair activities carried out by Iran under fire from the Iraqis.

According to estimates, these two disasters resulted in an oil spill of almost 80 million gallons. Some of the oil was cleaned up by skimmers and other tools, but as sand mingled with the floating oil at the surface, an estimated two-thirds of the total volume dropped to the seafloor as tarballs.

4. The 1994 Kolva River oil spill

Gallons of oil spilled: Approx. 84 million

A leak in a deteriorated oil pipeline in the Russian Arctic led to the Kolva River oil spill. For eight months, a dike kept the oil at the rupture site contained, but it eventually failed, allowing some 84 million gallons of oil to seep into the Kolva River.

Tundra and marshes of at least 72 square miles (186 square km) were contaminated by oil. Millions of gallons of oil were released into the environment through pipeline leaks, some of which made it to the Kolva River.

5. The 1992 Mingbulak (Fergana Valley) oil spill

9 biggest and worst oil spills of all time
The Fergana Valley oil spill was pretty nasty.

Gallons of oil spilled: Approx. 88 million

The deadliest oil leak in Asia and the worst land-based oil disaster in history happened in Uzbekistan on March 2, 1992. Oil spilled into a valley close to the city of Fergana after a well blowout.

Before the pressure in the hole started to drop, the oil caught fire and burnt for two months.

6. The 1979 Atlantic Empress oil spill

Gallons of oil spilled: Approx. 90 million

Around 10 miles (16 kilometers) off the islands of Trinidad and Tobago, the Atlantic Empress disaster dumped an estimated 90 million gallons of oil into the ocean.

The largest tanker spill in history occurred on July 19th, 1979, when the VLCCs Atlantic Empress and Aegean Captain collided during a tropical storm. The former took the brunt of the collision even though both ships caught fire, and the fire sparked an oil slick.

After being pulled away from the land, the Atlantic Empress burned for two weeks before sinking. However, the Aegean Captain's fire was put out, and the ship was towed to Trinidad.

Despite the massive amount of oil spilled during the accident, the beaches on neighboring islands suffered very little environmental harm; winds carried most of the oil out to sea, where it dispersed.

However, 27 sailors did lose their lives in the accident.

7. The 1979 Ixtoc 1 oil spill

Gallons of oil spilled: Approx. 126 to 140 million

Between June 1979 and March 1980, the Ixtoc 1 catastrophe in Mexico caused the flow of up to 140 million gallons of crude oil into the Bay of Campeche.

The Ixtoc 1 platform, which was drilling exploration wells in 164 feet (approximately 50 meters) of water, experienced an explosion that started the spill. When the drilling mud failed to circulate, an accumulation of oil and gas in the pipe led to the explosion.

The blowout preventer wasn't working, so when workers tried to remove the drill so that material could flow back down the line and fill the hole, a slurry of mud, oil, and natural gas rushed up the pipe and bypassed it.

The gases caught fire when they touched the whirling motors on the surface. Over the following nine months, between 126 and 140 million gallons of oil were released into the southern Gulf of Mexico.

Some of this oil washed up on the beaches from the western Yucatan Peninsula to southern Texas, causing hundreds of millions of dollars worth of lost tourism revenue and a decline in commercial fishing in the area for up to five years.

8. The 2010 BP Deepwater Horizon oil disaster

Gallons of oil spilled: Approx. 134 to 210 million

On April 20, 2010, a surge of natural gas blasted through a cement well cap that had just been set up to plug a well dug by the Deepwater Horizon oil platform, causing the largest unintentional oil spill in history to start in the Gulf of Mexico.

When the gas ignited on the platform after traveling up the rig's riser, it killed 11 workers and injured 17. Two days later, the oil platform flipped over and sank.

According to the U.S. District Court's findings, 134 million gallons of oil were leaked before the well was sealed up on September 17, and about 1,300 miles (2,100 km) of the U.S. Gulf Coast from Texas to Florida were covered in oil.

According to some accounts, the amount of oil discharged may have reached 210 million gallons.

The oil firm BP, which was found to be at fault, agreed to pay $65 billion in settlements to those whose livelihoods depended on the Gulf of Mexico.

9. The 1991 Persian Gulf War oil spill

Gallons of oil spilled: Believed but not confirmed to be between 380 and 520 million

As previously mentioned, this is possibly the worst oil spill in history if estimates of spilled oil are accurate. What's more, it did not happen by chance.

Iraq's leader, Saddam Hussein, gave the order to invade and occupy Kuwait on August 2, 1990, with the ostensible goals of obtaining Kuwait's substantial oil reserves, paying off a significant debt Iraq owed Kuwait, and enhancing Iraqi authority in the area.

To drive the Iraqis out, the United States formed a coalition that included the British, French, Egyptians, Saudis, Syrians, and others.

In January and February 1991, Iraqi forces withdrew after a significant air and ground operation, but not before lighting hundreds of Kuwaiti oil wells on fire, which burned for months.

Iraqi forces also discharged hundreds of millions of gallons of oil from Kuwait's Sea Island terminal into the northern Persian Gulf before hostilities ended, to dissuade the coalition from deploying marines and other amphibious troops in northern Kuwait and southern Iraq.

According to some reports, between 380 and 520 million gallons of oil were deliberately dumped into the Gulf.

And that is your lot for today.

Oil spills are some of the worst environmental disasters our species can wreak on the environment. While many are unintentional (for obvious reasons), some of the worst were created intentionally and could have been avoided.

Thankfully largescale oil leaks have become rarer over time. Still, the next "big one" is an ever-present occupational hazard if existing ships and pipelines are not maintained and operated safely.