Ship exhaust can increase Arctic warming

Soot produced by ship exhaust can increase warming on ice and snow because its black and absorbs warmth. (PHOTO BY JANE GEORGE)

Scientists say shipping traffic may speed up the rate of climate change in the Arctic because of its dirty, heat-absorbing exhaust.

Increased Arctic shipping may provide commercial and social development opportunities to the region, but its warming impact on the local environment is worrisome, says the international team of scientists whose study was published this month in the journal of Atmospheric Chemistry and Physics.

For their study, the scientists assumed ship traffic diverting from current routes to new routes through the Arctic will reach two per cent of global traffic by 2030 and five per cent in 2050.

But even if shipping through the increasingly ice-free Northwest Passage shaves 25 per cent of the travel distance from one coast of North America to the other, the tradeoffs of time and fuel must be balanced against the short-term environmental impact of shipping exhaust, the study’s authors say.

Previous studies have shown shipping exhaust contributes to global warming and can affect the human health through the emissions of greenhouse gasses and other substances, including what’s called black carbon or soot.

Soot, produced in large amounts by the exhaust of container ships, cargo ships, bulk ships and passenger ships, has a large impact in the Arctic because it absorbs warmth from the sun, which helps to melt snow and ice and warm the land or ocean.

Looking ahead to 2030, the team says up the 4.5 gigatons of black carbon that ships will dump in the Arctic could increase the warming impact of their greenhouse gas emissions by some 17 to 78 per cent.

Controls, such as seawater scrubbers that absorb sulphur dioxide emitted during the burning of diesel fuel, could reduce amount of Arctic black carbon produced from shipping in the near term and hold “nearly constant” through 2050, the study’s authors say.

But there’s a problem not addressed in their study.

Two-thirds of the shipping industry, which employs more than a million people worldwide, is located in poor countries. There, its 100,000 ships— many of which were made 30 years ago when no one worried about dirty exhaust— are the mainstay of the economy.

So, the shipping industry doesn’t want to see changes that will create any barriers to trade or see rich nations like Canada make expensive retrofits to their fleet while poorer countries continue to operate their aging, polluting ships as they do now.