Progress comes slowly to the world of commercial shipping, but it is coming.
Three years ago, we noted that one giant cargo ship emits as much as 50 million cars.
Now, shipping lines are starting to experiment with biofuels, which offer several advantages: They contain no sulfur or so-called aromatics--emissions of which will be globally limited starting in 2015--and if spilled in the ocean, they are biodegradable.
In an informative blog post by green industry analyst Pike Research, author MacKinnon Lawrence notes that the UN agency that regulates global shipping adopted rules last year that will reduce emissions of greenhouse gases by even those ships traveling on international waters.
Some individual nations already regulate such emissions within their coastal jurisdictions, which are less than 250 miles offshore and sometimes as little as 12 miles.
The culprit in all of this is so-called bunker fuel, which may be the dirtiest liquid fuel around. It's brown or black, and frequently so thick or sludgy it barely flows--consider it the equivalent of burning liquid asphalt, and you wouldn't be far off.
The cargo ships that use it produce up to 2,000 times the sulfur emissions that are allowed from the diesel fuel used in road vehicles. Compared to bunker fuel, conventional gasoline is practically filtered spring water.
Lawrence's article identifies two promising tests now underway for international cargo ships:
Bauta Docking by Flickr user PayPaulEnlarge Photo
Given that the first marine pollution treaty was signed in 1973, it will have taken 40 years to begin reducing the environmental damage from ocean shipping.
And if Maersk's prediction that 10 percent of shipping fleets will use biofuels by 2030 proves accurate, that's still a massively slower reduction in emissions than in the auto industry--which cut outputs of carbon monoxide (CO), hydrocarbons (HC), and nitrous oxides (NOx) by more than 90 percent from 1970 to 2010.
Greenhouse gases? Well, that's another story--although Europe, Asia, and North America are all in the process of adopting far stricter standards for either carbon emission reduction or improvements in fuel efficiency, which accomplish the same goal.
Meanwhile, today, just 20 giant cargo ships can create as much of certain types of airborne emissions as the world's total fleet of 1 billion vehicles.
Which makes news that some ships will soon get even somewhat cleaner a very good thing indeed.