Why slowing down ships could help save the planet

Shipping has long been one of the world’s dirtiest industries. Emissions from ships burn approximately 1 billion metric tons of carbon dioxide and other greenhouse gases every year, accounting for 3% of global emissions.

But a new study shows that putting speed limits on the ships that carry goods around the world could have broad environmental benefits.

Cutting ship speeds by 20% could reduce carbon dioxide emissions from ships by 24%, according to the study, as well as reduce the amount of nitrogen and sulfur oxides released into the atmosphere.

Carbon dioxide is a potent, heat-trapping gas and represents the main contributor to global warming. Two other classes of gases emitted by combustion engines, sulfur and nitrogen oxides, have been linked to certain respiratory illnesses.

The report also found that reducing ship speeds on the high seas by 20% could also cut noise pollution that threatens wildlife by around 67%.

The findings were produced by Seas At Risk and Transport & Environment — an umbrella group of European environmental and non-governmental organizations.

But just as car engines get better gas mileage at optimum speeds, as ships travel slower they burn less fuel, which in turn lowers the emissions their engines send into the atmosphere.

Without any changes to the industry, the United Nations’ International Maritime Organization (IMO) projects emissions from international shipping could increase by between 50% and 250% over the coming decades, depending on future economic growth. If that projection is accurate, ships could account for 17% of global carbon emissions by 2050.

Because of this, pumping the brakes on ships could have a major impact on efforts to fight global warming.

Reducing emissions by slowing speeds is something the shipping industry has already begun to adopt. Last year, when the IMO set a goal of reducing emissions by at least 50% by 2050 compared to 2008 levels, some of the largest shipping companies started slowing down their fleets to cut emission levels.

But there are limits to what slowing down ships can achieve.

Slower speeds will lead to lengthier travel times, and some estimates show a 20% speed cut could increase transatlantic voyages from cities like Buenos Aires, Argentina to Rotterdam, Netherlands, by nearly five days.

A study by environmental research group CE Delft projects that cutting shipping 30% would reduce the GDP of South American exporting countries by less than 0.1%.

Experts say deeper and longer-term emissions cuts can only be achieved through the development of alternative fuels, new engines and ships.