Tanker attacks in the Strait of Hormuz are spilling oil into the Persian Gulf

A dark, muddied patch of blue, incongruent with the rest of the ocean; a winding thread of silvery white; a reflective metallic sheen — these are some of the telltale signs on a satellite image that oil may be leaking into the water. 

Experts have identified these and many other visual signaturesin the Strait of Hormuz, leading them to conclude there's an environmental crisis playing out amid the US-Iran war, as tankers are struck by missiles, set on fire or sunk.

One recent example: In June, a Russian tanker carrying about 800,000 barrels of oil stranded off the coast of Oman, causing a major spill.  

Earlier in the war, there were as many as 85 large oil-laden tankers stuck in the Strait — that number has since dropped to 13, according to Greenpeace. Each stranded tanker, plus every other vessel trying to move through the waterway, poses a distinct risk for attack and thus a spill. Since the start of the war, the environmental organization has used satellite imagery to track more than 100 spills.

There are likely several other spills we don't know of, amid widespread GPS spoofing in the region that causes ships to broadcast false positions. Greenpeace released a reportthis week calling the situation an "ecological catastrophe" and pinpointing a number of oil slicks that are extending into protected and fragile ecosystems. 

"People should be concerned," Nina Noelle, a Greenpeace expert on environmental disaster relief, told DW. The war has taken "a very, very heavy toll on the environment," she added, with the damage now reaching new scales. 

Where is the oil spreading?

Greenpeace identified five major oil slicks earlier this week with a total visible area of 240 square kilometers (about 93 square miles) in the Strait of Hormuz. That's about four times the size of Manhattan. 

These patches of oil floating on the ocean's surface are getting smaller — now about 80 square kilometers — according to more up-to-date satellite images, as weather conditions have likely made the slicks disperse. But that does not mean the ecological impact is any less severe,  Noelle said. "Oil can also sink into the sediment and impact the ecosystems for years and years." 

What's concerning is where the slicks were identified. One was found near Musandam National Park, a protected area in Oman that's home to coral reefs, sea life and important breeding grounds for sea birds. Another is close to Iran's Minab River Delta and its protected mudflats and mangrove forests. This kind of damage can take decades for ecosystems to recover from. 

Tracking an unclear picture 

It's hard to say exactly how far the oil has reached and how severe the damage is.  

"What we have put out is the conservative estimate," Noelle said. "It might be worse. It's definitely not better." 

Greenpeace and other environmental organizations are relying on satellite images provided by the Copernicus Sentinel-1 and Sentinel-2 satellites. They're part of the European Union's Earth observation program and are publicly available. 

There are also private satellite providers like Planet Labs that tend to have higher-resolution images. But they've limited access to satellite imagery during the war to prevent their data from being used for military targeting. And there are limits to on-the-ground reports too. 

"We don't have a lot of information coming from the country itself, both in Iran as well as the Gulf states," Wim Zwijnenburg, an environmental researcher using open-source methods at the Dutch peace organization Pax, told DW. "There is quite restrictive policies of people posting imagery from what's happening on the shore." 

The toll on wildlife and people 

Oil pooling into the Gulf poses a number of threats, both to biodiversity and to humans. 

For sea birds, oil can be deadly. It coats their feathers, reducing their natural waterproofing and buoyancy, making it harder to stay afloat, fly, and hunt for food. Even small amounts of oil can damage eggs too, causing them not to hatch or to be born with deformities. 

Mangrove habitats, which provide safe harbor for coastal species, are also hit hard. 

"Mangroves have aerial roots and the oil is covering these roots like a film and actually hindering the mangroves in exchanging gases," Noelle said. "They're kind of suffocated by the oil. Most of the time, it leads to the trees dying." 

The risks extend to people as well. Coastal communities rely on fish that die off after being exposed to oil. And oil spills contaminate water used for Gulf states' drinking supply. Desalination — or converting seawater into drinkable water — is where 90% of drinking water in Kuwait comes from, along with about 86% in Oman and 70% in Saudi Arabia.  

Clean-up is no easy fix either. 

"It's unlikely that it will be addressed quickly, because of the war," Zwijnenburg said. "War in general makes it very difficult to respond fast to these kind of emergencies. There are a range of limitations because of the military movement, because of mines — so it's very difficult to get vessels and clean-up operations to start." 

Environmental groups have pointed to the war in Iran — and the rising scale of oil spills it's causing — as further evidence that the world needs to move away from its dependence on fossil fuels. 

"The most sustainable long-term damage prevention for things like that would be to reduce and ultimately end our dependency on oil and gas," Noelle said. "Because as long as our energy systems and transport routes are centered around fossil fuels, there will be a continued environmental risk." 

Edited by: Sarah Steffen
 

How much oil is getting through the Strait of Hormuz?