Only 0.5% of 90,000 oil slicks reported over five-year period, analysis finds

The Guardian

2 days ago

Just 474 out of more than 90,000 oil slicks from ships around the world were reported to authorities over a five-year period, it can be revealed, and barely any resulted in any punishment or sanctions.
The figure, obtained from Lloyd's List by the Guardian and Watershed Investigations, shows the pollution incidents reported between 2014 and 2019, compared against a scientific study using satellite imagery that counted the number of slicks from ships over the same period.
Furthermore, all oil slicks from ships visible by satellites are illegal because they exceed pollution limits by at least three orders of magnitude, new research by Florida State University has found. Many of the slicks are the result of ships deliberately discharging bilge water containing oil in order to keep the vessels stable.
'The level of under-reporting of pollution is a huge unknown,' Dr Elizabeth Atwood from Plymouth Marine Laboratory said. 'The argument that has historically been made is that there is an equal amount coming from natural seeps. But recent research keeps underlining that this is not true for much of the globe,' said Atwood.
Hugo Tagholm, the executive director of Oceana UK, said: 'It is appalling to hear of the extreme levels of toxic pollution caused by these oil spills from shipping, as well as the frankly mind-bending under-reporting of the situation.'
Extensive analysis by scientists of hundreds of thousands of satellite images of slicks in the world's seas between 2014 and 2019, found that 20% – or 90,411 – originated from ships and added up to about the size of Italy, with 21 high-density slick belts coinciding with shipping routes. In comparison, 2% were from oil platforms and pipelines, and just over 6% from natural oil seeps on the ocean floor. The rest were either from land sources or unidentified ships.
'Our data show that these spills represent persistent and widespread violations,' said Ian MacDonald, a retired professor of oceanography from Florida State University and coauthor of the paper.
The researchers say this is the first time that real world data has proven that properly treated discharges do not leave a visible trace.
'It suggests that bilge dumping has been a pervasive issue in the global oceans for decades,' said Carrie O'Reilly, the lead author at Florida State University.
Yet only a fraction of these pollution incidents have faced any sanction under the international convention for the prevention of pollution from ships (Marpol).
'It's hard to think of a case where a transient oil slick would have invited regulatory action,' said McDonald, who believes the time and expense of bringing a case against a well-financed shipping company is prohibitive.
In European waters for example, despite EU pollution laws that sometimes surpass Marpol in stringency and satellite-based systems being utilised, enforcement remains uneven with limited penalties and few prosecutions, the European court of auditors warned in March.
'In our recent audit of EU actions tackling sea pollution by ships, we concluded that polluting ships can still slip through the net,' said Nikolaos Milionis, the ECA member responsible for the audit.
'In particular, we found that EU countries check fewer than half of the possible spills detected by the EU satellite-based system. In the end, they confirmed pollution in only 7% of the cases. This shows both limitations in the technology and in the means used by member states to check the alerts,' Milionis said.
The auditors concluded that pollution from ships was a serious problem and that with more than three-quarters of European seas estimated to have a pollution problem, the EU's zero-pollution ambition to protect people's health, biodiversity and fish stocks was out of reach.
In another new study of satellite images off the coast of six west African countries from 2021 to 2022, Atwood found that 16% of slicks, covering roughly the size of 28,800 football pitches, were from ships. In that same timeframe no incidents were recorded by international marine pollution authorities off the coasts of Benin, Ghana, Ivory Coast, Sierra Leone, Liberia and Togo.
Experts have warned these chronic spills are threatening sea life.
'All visible slicks should be considered harmful to the marine environment, especially given that trace quantities of oil are damaging to planktonic organisms, which form the base of the marine food web,' said O'Reilly.
Sign up to Down to Earth
The planet's most important stories. Get all the week's environment news - the good, the bad and the essential
after newsletter promotion
'Individually the volumes of oil are pretty small, nonetheless, when you add up all the ship traffic, and we should note that ship traffic and the occurrence of these oil slicks is increasing over time, the cumulative effect is certainly significant,' McDonald said.
Much of the pollution from ships comes from what is known as bilge dumping. Oil and potentially toxic liquids from the engine room of a ship accumulate in the lowest part of a ship, known as the bilge. Ships need to get rid of bilgewater because, if left unchecked, it can affect a ship's stability and be corrosive, leading to safety hazards. It can legally be released at sea if it is treated by an oily water separator, which large ships have onboard, but that does not always happen.
'Some vessels might be badly maintained and the bilge will be filling up constantly,' said a mariner who wishes to remain anonymous. 'It takes time to go through the separator, so to keep on top of it, the oil water separator is bypassed. Or the separator might be broken.'
Bilgewater could also be off-loaded at port for treatment, but this is costly.
'Commercial pressures in shipping are huge. It's all about profit and any savings you can make. Being in port is the most expensive time of the journey. There are port fees, pilotage fees, it's expensive and the less you do at port and the less time you spend there, the cheaper it is,' explained the mariner.
He also questioned whether there were enough inspectors at ports to check ships and scrutinise their oil logbooks.
A spokesperson for the International Maritime Organization (IMO) said: 'Oil and bilgewater operational discharges at sea by ships are regulated under the Marpol convention annex I. Ships must carry a mandatory oil record book, which should record all oil and sludge transfers and discharge, and allows for checks and monitoring by flag and port states … [which] have the remit and responsibility for implementation of IMO treaties.'
Ocean conservationists such as Tagholm want more action to be taken to clean up the shipping industry.
'Tankers, carrying oil and gas across the world, make up a third or more of all shipping,' he said. 'If we ended our addiction to fossil fuels – as we must to prevent climate breakdown – we would also halt the severe consequences of these spills, from disrupting the foundations of marine food chains.'
This story was produced in partnership with the Pulitzer Center's Ocean Reporting Network