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The number of oil spills globally has declined significantly

Over the past five decades – the time for which we have data – oil spills from tankers decreased very substantially.

The dataset produced by the International Tanker Owners Pollution Federation (ITOPF) covers data on oil spills globally since 1970.

This is first shown year-by-year, then in the second chart, as the annual average per decade for large oil spills.

In the 1970s there were 24.5 large oil spills per year; in the 2010s the average number of large oil spills decreased to 1.7 oil spills per year.

Quantity of oil spilt

In this section

The quantity of oil spilt each year has declined

The number of oil spills in a given year has decreased significantly over the last five decades. So, too, has the quantity of oil spilled each year.

The International Tanker Owners Pollution Federation (ITOPF) also publishes annual data on the total amount of oil spilt – in tonnes – and has done so since 1970.

This is first shown year-by-year, then in the second chart, as the annual average per decade.

Over the last 50 years the annual quantity of oil spilled has decreased significantly.

Oil spills unrelated to tankers

According to the ITOPF dataset, the largest oil spill caused by a tanker was caused by the SS Atlantic Empress, which sank close to Trinidad and Tobago in 1979.

Wikipedia lists five oil spills which were not caused by tankers that were larger than this:

  • The biggest oil spill in history was the Lakeview Gusher (1910-11 in California),
  • the second biggest was the Gulf War oil spill (1991),
  • the 3rd biggest was the Deepwater Horizon (2010),
  • 4th was Ixtoc I oil spill in Mexico (1979-1980)
  • and 5th was a long-lasting spill in the Niger Delta between 1976 and 1996.

Data Sources

The International Tanker Owners Pollution Federation (ITOPF) maintains a database on oil spills caused by tankers, combined carriers and barges since 1970. The data covers the entire planet. The database can be found here . For all of these the ITOPF data base records the type of oil spilled, the spill amount, the cause and location of the incident and the vessel involved. The size of a spillage is grouped into three categories: less than 7 tonnes, 7-700 tonnes, and more than 700 tonnes of oil spilled. The majority of incidents belong to the smallest category of spillages. Nowadays oil spills can be detected by computer systems on the basis of satellite images. For the past, data is taken from other sources: Data on smaller spills are taken from the vessel owners and their insurers. For the larger spills the majority of information is taken from published sources of the shipping press.