Oil Tanker Spill Statistics 2023

Spill frequency

Over the past half century, statistics for the frequency of spills greater than 7 tonnes from tankers have shown a marked downward trend, as illustrated in Figure 1 below.

The average number of spills per year in the 1970s was approximately 79. This decreased by over 90% to 6.3 in the 2010s and remains at a similar level for the current decade. 

It is interesting to note the progressive reduction in the number of spills when data is analysed per decade, as demonstrated below (Figure 2).

A quarter of all spills recorded over 7 tonnes are large (>700 tonnes). More than half of these large spills (52%) occurred in the 1970s (see Figure 3 below).

Tanker spills vs seaborne oil trade

While increased tanker movements might imply increased risk, it is encouraging to observe that the downward trend in oil spills continues despite an overall increase in oil trading over the period, as illustrated below (Figure 4).

Spill quantity

Alongside the reduction in spill frequency, there has been a significant decrease in the quantity of oil spilt through the decades. In the 2010s approximately 164,000 tonnes of oil were lost from tanker spills of 7 tonnes and above, a 95% reduction since the 1970s. The figure for the present decade is currently 28,000 tonnes (4 years of data).

In terms of the volume of oil spilt, the figures for a particular year may be severely distorted by a single large incident. This is illustrated clearly by incidents such as ATLANTIC EMPRESS (1979), 287,000 tonnes spilt; CASTILLO DE BELLVER (1983), 252,000 tonnes spilt; ABT SUMMER (1991), 260,000 tonnes spilt and SANCHI (2018), 113,000 tonnes spilt (see Figure 5 below),

Frequency & quantity by decade

When the frequency and quantity of oil spilt are reviewed together, the influence of a few very large spills on the estimated quantities per decade can be seen (Figure 6):

• In the 1990s there were 358 spills of 7 tonnes and over, resulting in 1,134,000 tonnes of oil lost; 73% of this amount was spilt in just 10 incidents.
• In the 2000s there were 181 spills of 7 tonnes and over, resulting in 196,000 tonnes of oil lost; 75% of this amount was spilt in just 10 incidents.
• In the 2010s there were 63 spills of 7 tonnes and over, resulting in 164,000 tonnes of oil lost; 91% of this amount was spilt in just 10 incidents. One incident was responsible for about 70% of the quantity of oil spilt.
• In the 2020s to date, there have been 27 spills of 7 tonnes and over, resulting in 28,000 tonnes of oil lost. 91% of this amount can be attributed to 5 large incidents and 9% to the remaining 22 incidents. (This decade is not included in Figure 6 as only four years of data are available.)

Most oil spills (>7 tonnes) recorded between 1970 and 2023 were caused by Allisions/Collisions and Groundings (Figure 7).

A summary of the 20 largest tanker spills that have occurred since the TORREY CANYON in 1967 is given below. It is of note that 19 of the 20 largest spills recorded occurred before the year 2000. SANCHI, the latest addition to the list, is the only major spill of non-persistent oil featured here and it resulted in significantly lower environmental impacts compared to some crude oil spills listed.

A number of the incidents, despite their large size, necessitated little or no response as the oil was spilt some distance offshore and did not impact coastlines. For this reason some of the names listed may be unfamiliar.

PRESTIGE, EXXON VALDEZ and HEBEI SPIRIT are included for comparison although these incidents are further down the list.