Air pollution from ships – a serious threat

Emissions from ships may bring as much nitrogen oxide to the atmosphere as the total amount of emissions coming from the USA. International shipping along the Norwegian coast and in the Northern Atlantic Ocean contributes largely to the formation of ground-level ozone and acidification of the shores.

Air pollution from ships may be twice as bad as shown by previous estimates. In high traffic areas emissions may affect the climate just as much or even more than other forms of emissions. This was stated during a conference on Norwegian climate research, held by the research programme NORKLIMA recently. NORKLIMA is a new and extensive ten year programme focusing on a better understanding of climatic changes in a wide perspective.

A call for action

The transportation of freight by ship is widely regarded as an environmental form of transportation. So far scientists have been uncertain as to what may be the consequences of ships’ exhausts to the environment.

“Emission from ships is one of the fastest growing emission sectors. If the new reports are confirmed, steps must be taken, like we have done with other emission sources,” says Stig Dalsøren at the Department of Geosciences, University of Oslo.

Scientists at the research department of Det norske Veritas (DNV) have concluded that emissions of greenhouse gasses such as carbon dioxide may contribute to global warming, much like emissions from aviation.

The cooperation between the Department of Geosciences and DNV aims to estimate how shipping affects the formation of ground-level ozone, acidification and global warming.

Like the entire USA

Although the topic is discussed internationally, it is widely agreed upon the fact that previous emission estimates have been too low. Scientists in Germany and the USA claim the emissions are higher than what is shown by the estimates of Norwegian scientists.

“American scientists have concluded that the emissions of nitrogen oxides (NOx) from ships are as high as the entire amount of emissions coming from the USA,” says Stig Dalsøren.

“They claim that a single industry, shipping, is as large a burden to the environment as one of the greatest air polluters of the world.”

Complicated cocktail

Tankers, cargo ships and other vessels emit a complicated “gas cocktail” into the Earth’s atmosphere. The fuel used by many ships, the so-called bunker oil, contains especially large concentrations of nitrogen and sulphur.

In areas with a lot of shipping traffic, for instance in the Northern Atlantic, the scientists show that the ships contribute largely to the formation of ground-level ozone and acidification.

“Emissions form many different gases in the atmosphere, like ozone, known as greenhouse gas, which is hazardous to health, agriculture and vegetation. And there is sulphate, found in acid rain, which also affects the climate,” Dalsøren explains.

“The experts estimate a 100 percent increase in ground-level ozone over the Northern Atlantic Ocean and up to 10 percent increase of the acidification in certain coastal areas,” Dalsøren says.

Expert disagreement

The measurements are based on the sale of ship fuel and engine consumption. However, the level of emissions from ships is hard to estimate, because it is spread all over the world. Scientist Øyvind Endresen and his colleagues at DNV estimate that the total amount of emissions is less than what has been suggested by the Americans.

“There is disagreement about the number of days of operation, the speed and engine power of the ships and how the fuel consumption varies accordingly,” says Dalsøren.

No regulations

According to the scientists, the subject at hand has not been given sufficient attention. This is because it has been hard to measure the extent of the problem.

“The calculations of pollutant emissions have not been good enough. Although it has been suspected that the effects are considerable, there have been few restrictions. And toxic emissions from ships are not included in the Kyoto protocol.”

The International Maritime Organisation (IMO) has realised that measures must be taken, which will happen when, or if, a sufficient amount of countries ratify a new international convention to reduce emissions from ships.