Clear The Air Ships Air Pollution Blog Rotating Header Image


Ship Pollution Patterns Tracked From Space

For more than a decade, scientists have observed “ship tracks”in natural-color satellite imagery of the ocean. These bright, linear trails amidst the cloud layers are created by particles and gases from ships. They are a visible manifestation of pollution from ship exhaust, and scientists can now see that ships have a more subtle, almost invisible, signature as well.

Data from the Dutch and Finnish-built Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite show long tracks of elevated nitrogen dioxide (NO2) levels along certain shipping routes. NO2, is among a group of highly-reactive oxides of nitrogen, known as NOx, that can lead to the production of fine particles and ozone that damage the human cardiovascular and respiratory systems. Combustion engines, such as those that propel ships and motor vehicles, are a major source of NO2 pollution.

The map above is based on OMI measurements acquired between 2005 and 2012. The NO2 signal is most prominent in an Indian Ocean shipping lane between Sri Lanka and Singapore, appearing as a distinct orange line against (lighter) background levels of NO2. Other shipping lanes that run through the Gulf of Aden, the Red Sea, and the Mediterranean Sea also show elevated NO2 levels, as do routes from Singapore to points in China. These aren’t the only busy shipping lanes in the world, but they are the most apparent because ship traffic is concentrated along narrow, well-established lanes.

The Atlantic and Pacific Oceans also have heavy ship traffic, but OMI doesn’t pick up NO2 pollution tracks because the shipping routes are less consistent. The shapes of landmasses force ships into narrow paths in the Indian Ocean, while ships in the Atlantic and Pacific tend to spread out over a broad areas as they navigate around storms.

In addition, the air over the northeastern Indian Ocean is relatively pristine. Heavy NO2 pollution (dark red in the map) from cities and off-shore drilling activity along the coasts of China, Europe, and the United States obscures the ship tracks that might otherwise be visible to OMI. In the map, the Arctic is gray because the lack of light during the winter and frequent cloudiness during the summer prevented OMI from collecting usable data in the area.

Urban areas and industrialization aren’t the only source of NO2 in the map. Agricultural burning in southern Africa and persistent westerly winds make an elevated band of NO2 that stretches from southern Africa to Australia. (In central Africa, easterly winds push pollutants from fires toward the Atlantic, keeping NO2 levels comparatively low over the northern Indian Ocean.) Lightning, which produces NOx, also contributes to background NO2 levels.

Just how much shipping contributes to overall NOx emissions remains an open question for scientists. Research suggests that shipping accounts for 15 to 30 percent of global NOx emissions; scientists are using satellite observations to reduce the uncertainty in such estimates.

OMI is not the only satellite instrument observing NO2 levels in the atmosphere. The Global Ozone Monitoring Experiment (GOME) instruments on the European Space Agency’s ERS-2 and MetOp-A satellites, as well as the SCIAMACHY instrument on the Envisat satellite, have made similar measurements. In 2012, Dutch scientists published a study combining data from all four instruments to show that the NO2 signal over major shipping increased steadily between 2003 and 2008, then dropped sharply due to the global recession and reduction in ship traffic.

NASA Earth Observatory image by Jesse Allen, using OMI NO2 data provided courtesy of Lok Lamsal, Aura Project Science Office. Caption by Adam Voiland, with information from Nickolay Krotkov, Anne Thompson, Geert Vinken, and Folkert Boersma.


Aura – OMI

Ship Pollution Patterns Tracked From Space

Feb 14, 2013 11:39 AM ET // by Christina Reed

City pollution from cars smogging your view? Have a look at the coastal pollution in the map shown above. It’s not an atmospheric pollutant that you can see with your naked eye, but its presence can lead to cardiovascular and respiratory problems in humans.

What is it? Nitrogen dioxide (NO2), which in elevated amounts lead to unhealthy levels of nitrogen oxides (NOx), fine particles, and ozone in the air we breath.

Just what is causing this red alert pattern along the coasts? That’s the rub, it’s a combination of city pollution, off-shore drilling, and ship traffic.

Ships and airplanes can both leave whispy cloud tracks called “contrails” in the air that are easily seen from space.

Shaving Cream Prank or Ship Tracks?

But the specific amount of NO2 that ships release near the coasts gets lost among the other emissions of nitrogen oxides from other pollution sources.

Shipping is estimated to contribute 15 to 30 percent to the global NOx pollution. To test this, several satellites are monitoring atmospheric NO2 levels. This map shows the ocean and sea-based contribution of NO2 into the atmosphere from 2005 to 2012 as measured by a Dutch and Finnish-built Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite.

Take a look at the difference between the hazy NO2 level drifting between southern Africa and Australia, the result of westerly winds blowing soot from fires in Africa across the Indian Ocean, and the distinct red line along the transoceanic shipping route between Sri Lanka and Singapore.

Eight Unbelievable Cruise Ship Disasters

Other areas of the ocean such as in the Pacific and the Atlantic have just as much shipping traffic, but the routes do not leave such a precise NO2 trail for the satellite to detect, because in those waters ships are often forced to skirt around storms.

Earth and climate scientists work with maps like this one to help better evaluate the human contribution to atmospheric pollution.

Slaughter of the seabirds: Polluting ship feared responsible for killing thousands of birds in Channel

It is feared several thousand birds, mainly Guillemots, have become virtually paralysed after swimming into the ‘waxy’ substance in the Channel

One of the injured seabirds

One of the injured seabirds


A rogue cargo ship is the likely cause of an environmental disaster that has left hundreds of birds dead after it flushed a glue-like pollutant into the sea, it was claimed today.

Officials from the Maritime and Coastguard Agency are awaiting the results of urgent tests to establish what the mystery substance is before launching a hunt for an offending vessel.

The MCA meanwhile launched a pollution surveillance aircraft to survey the English Channel while the Royal Navy and RAF were on standby to help.

Experts said the leading theory for the cause of the pollution is that an oil residue was illegally flushed from a ship’s cargo tanks out at sea to save the time or costs of emptying it in port.

It was feared several thousand birds, mainly Guillemots, have become virtually paralysed after swimming into the ‘waxy’ substance in the Channel.

The substance, believed to be palm oil, has glued the birds’ feathers and wings together, preventing them from flying.

There are also mounting fears that a 25,000-strong population of Auks off the Dorset coast may perish in the ‘ecocide’.

Over the last 48 hours hundreds of seabirds have been washed ashore on beaches in West Sussex, Hampshire, the Isle of Wight, Dorset, Devon and Cornwall.

Wildlife experts have so far rescued more than 250 birds alive but as time goes by it is feared the majority of birds now found will be dead.

Because they are unable to take off or preen themselves, the creatures are at grave risk of freezing to death as they are washed onto the windswept beaches.

One of the injured seabirds

One of the injured seabirds


Chris Packham, presenter of BBC’s Springwatch and Autumnwatch, said: “What’s particularly frightening is that hundreds have been picked up on the beach, there could be very many more which have died and been lost at sea.

“The birds that have been found up until now are probably the tip if the iceberg. There could be thousands out there that have died in this.”

Dr Simon Boxall, an oceanographer at the University of Southampton, said: “The substance has the right characteristics to be palm oil.

“We move a lot of it around the world and transport it in tens of thousands of tonnes at a time.

“The fact this has affected such a wide area implies there is a reasonably large amount in the sea which is moving up the Channel and implies there has been a spill.

“It is likely a ship has delivered some palm oil but needed to deposit residue from the tanks.

“It takes time to do so and costs money so a few rogue ships have been known to flush out its tanks in the open sea, which can be several hundred tonnes.

“Each ship has identification saying where it is has come from, going to, and what cargo it is carrying, so the authorities could narrow this down to half a dozen ships.”

Although the majority of the birds affected are guillemots as they spend most of their life on the surface of the sea, other species that have been coated in the substance have been razorbills, kittiwakes, egrets and a baby puffin.

Most of the rescued birds have been recovered along a 25 mile section of coast at Chesil Beach and the Isle of Portland in Dorset.

More than 120 of them have been taken to an RSPCA centre to be cleaned using a mixture of water and margarine but at least 50 were found dead.

Nearly 100 birds have been rescued from beaches in Torquay, Brixham, Teignmouth and Salcombe in Devon.

Mark Smith, of the Dorset Wildlife Trust, has been leading an army of 18 staff in the search for birds along Chesil Beach.

He said: “There are 25,000 auks off Dorset so the potential number of birds involved in this could be huge.

“This is potentially quite a big environmental disaster.

“Unfortunately as time goes by the proportion of birds that we are find are dead than alive.

“Whatever the substance is, it feels like a very sticky glue that has clumped the feathers together.

“The birds are left almost paralysed. They can’t fly or preen themselves and just go along with the tide and winds until they hit the shore.

“We have found many birds stuck to the pebbles on the beach while others have pebbles stuck to their feathers.

“Most of the dead ones have frozen to death from where they have been unable to dry their feathers and then exposed to cold winds while stranded on the beach.”

The Environment Agency is currently testing a sample of the substance in order to confirm exactly what it is and, potentially, where it came from.

Fred Caygill, spokesman for the MCA, said: ”Ships do clean their tanks at sea.

“In some cases it can be done legitimately and in other cases it can breach the maritime pollution regulations.

“We will continue to monitor this situation and await the results of the analysis of the product before we respond.”