Are Major Oil Spills Becoming Less Frequent?

While the latest reports from the International Tanker Owners Pollution Federation (ITOPF) suggest major oil spills have declined significantly over the past few decades, environmental campaign groups such as Greenpeace maintain every spill is one too many.

In the 1970s the industry reported around 80 ‘major’ spills a year, each seeing more than seven tonnes of oil leak into the ocean. Over the past decade this figure has fallen to just six major spills per year, despite a significant increase in the number of oil tankers operating in oceans. ITOPF representative Naa Sackeyfio credits the reduced number of spills to tighter regulations and improved safety standards.  

Greenpeace warns small spills have a big impact

While ITOPF interprets the data as positive, Greenpeace says the report fails to capture the alarming number of ‘small’ spills that see less than seven tonnes of oil leak into the ocean. These account for more than 80% of all marine oil spills and have a big environmental footprint. Because they are smaller in size, these types of spills are often not reported and harder to track. Greenpeace also says the ITOPF figures only include tankers, bulk carriers, floating oil storage vessels and barges, meaning other vessels could be leaking oil into the ocean without spills being reported.

"Even a single spill is one too many. Currently, there are many devastating ongoing spills in the world," says Greenpeace representative Tal Harris.

How oil spills occur

While some spills occur when a ship runs aground, others are sparked by collisions. Between 1970 and 2019, around 50% of all major spills were caused either by ships running aground, hitting other vessels of colliding with an underwater obstacle. The risk of spills significantly increased when vessels were navigating through ports, harbours and inland waterways. One of the most recent major spills occurred when a Japanese-operated ranker ran aground just off the island of Mauritius. More than 1000 tonnes of oil leaked into the Indian Ocean and posed a serious threat to the delicate marine ecosystem.

The environmental impact of oil spills

As oil is less dense that water it collects on the surface of the ocean and creates a slick that can coat the feather and fur of marine birds and mammals. This compromises their ability to repel water and leaves them exposed to the elements. Animals can also swallow water which can cause illness and death.

“Even relatively small volumes of oil can spread widely and cause a major impact, especially if they occur close to shore in calm weather and in sensitive marine habitats," says Greenpeace scientist David Santillo.

Alongside spills, the oil industry has also come under fire for its fuel emissions. Find out more about how the sector is working to clean up its act in ‘An analytical approach to marine fuel standards.’