New map shows how oil slicks are smothering our oceans – with one hotspot in Europe
More than 90 per cent of the estimated oil pollution in the oceans occurs within national waters – including in protected areas. Oil slicks cover an estimated 1.58 million square kilometres of the world’s oceans each year, according to a new satellite analysis that exposes the scale of pollution at sea. That amounts to an ...
Oil pollution covers vast areas of the world's oceans, with over 90 percent occurring within national waters, including protected regions. A new satellite analysis conducted by SkyTruth reveals that oil slicks span approximately 1.58 million square kilometers yearly, equivalent to an area three times the size of Spain. Most of these pollution sources are small, rendering them less publicized compared to headline-grabbing incidents like the Deepwater Horizon spill.
According to the analysis, ships were responsible for around 81 percent of the oil slicks whose origin could be identified. Shipping vessels, particularly oil tankers and cargo ships, were the primary contributors, while offshore oil and gas infrastructure accounted for 18 percent. SkyTruth's chief technology officer, Karl Wuster, emphasizes that oil pollution is a persistent global issue, far more frequent than significant spills that attract media attention.
The analysis, released during Climate Week NYC in September 2023, utilized satellite observations from 2023 to 2025 combined with data from SkyTruth's Cerulean oil pollution monitoring system. Researchers modeled annual pollution from vessels and offshore facilities, considering variations in satellite coverage and vessel density. The highest concentrations of oil pollution were found in the Red Sea, Persian Gulf, Mediterranean, Black Sea, waters off West Africa, and around Indonesia.
Notably, several vessels and facilities repeatedly appeared in satellite images linked to oil slicks. These repeat polluters included a Palau-flagged cargo ship, a Russian oil tanker, an Indonesian oil tanker, and specific offshore facilities, particularly one off the coast of Indonesia and another off the coast of Nigeria. Even protected waters are not spared from oil pollution; although 75 percent of marine protected areas exhibited lower concentrations of oil slicks compared to their surroundings, pollution was still detected in sensitive habitats, such as the habitat of the critically endangered Rice’s whale in the Gulf of Mexico.
The researchers also caution that the full extent of the problem remains unclear due to limited satellite coverage over the high seas, leaving vast expanses of the ocean inadequately monitored. Conflicts, accidents, and shipwrecks contribute to the pollution issue. In August, oil from a carrier struck during the war in the Gulf reached Iran’s Qeshm Island and its protected mangroves.
A Russian shadow fleet tanker off Oman spilled over 2,000 square kilometers, while a mysterious vessel that capsized off Tobago in 2024 covered nearby beaches in oil, leading to a national emergency. A passenger ferry that ran aground in Sweden in 2023 left a five-kilometer oil slick in the Baltic Sea that eventually reached the coast.
Additionally, an estimated 8,500 potentially polluting shipwrecks, mostly from the two world wars, lie on the ocean floor, some of which are already leaking oil as their hulls corrode.
Written by urgent.news from Hellenic Shipping News's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.