Decreasing speed cuts emissions, wildlife collisions and costs

Arctic shipping has already increased by 111 per cent over the past decade—and it is projected to continue accelerating as multi-year and summer sea ice diminishes due to climate change. KRISTEN POWELL explains how slow steaming can minimize harms to wildlife and the climate while cutting costs for operators.

Arctic species that were once largely buffered from the industrial activities affecting their southern counterparts are now threatened by the impacts of shipping—from underwater noise pollution to ship strikes and the effects of climate change from emissions. Could “slow steaming” be the obvious solution?

Slowing down is not a new idea. In other parts of the world, the shipping industry has relied on strategically reducing speeds to increase energy efficiency, curb fuel use and save costs for decades.

Ships frequently travel faster than their optimal fuel-efficient speed of 10 to 14 knots, depending on variables like vessel type, design and sea conditions. But the faster a ship goes, the more dramatically its fuel consumption rises. This means that even small reductions in vessel speed can lead to significant improvements in fuel efficiency. Decreasing a ship’s speed by just 10 per cent can reduce its overall energy use by 20 to 30 per cent even though the voyage itself takes longer. These benefits can be even greater for certain ship classes and designs or vessels travelling longer routes.

Environmental benefits

The case for slow steaming becomes even more compelling when benefits to the environment are considered, such as:

• Emissions reductions. By reducing speed (and burning less fuel), ships can significantly lower their greenhouse gas emissions. Research shows that a 10 to 20 per cent reduction in speed will cut baseline carbon emissions by 13 to 24 per cent. Given shipping’s outsized contribution to the climate crisis, speed reduction is a simple way to support climate goals, including those established by the International Maritime Organization, which has set a net-zero emissions target for international shipping by 2050.
• Underwater noise. Slower speeds substantially reduce underwater noise pollution, protecting Arctic marine mammals like belugas, narwhal and bowhead whales, which depend on sound to navigate, hunt and communicate. Research shows that a 10 per cent speed reduction can decrease noise pollution by 40 per cent, while a 20 per cent speed reduction can decrease noise pollution by 67 per cent.
• Ship strikes. Reducing ship speed significantly decreases the risk of fatal collisions with whales by giving both whales and ship operators more time to detect each other, react and avoid contact. The probability of death or serious injury to a whale in the event of a ship strike increases directly with speed: travelling at less than 11.8 knots cuts that chance by more than half, while speeds above 15 knots increase the risk exponentially toward 100 per cent.
• Vessel safety. The Arctic Ocean’s extreme weather, poor visibility, sea ice variability and poorly mapped seafloors pose significant navigational challenges. Operating at lower speeds improves reaction time, which can help ships avoid obstacles like ice floes and wildlife. It can also reduce the risk of accidents, such as groundings or collisions, which can lead to catastrophic fuel spills. Slower speeds even reduce mechanical wear and tear, supporting more reliable operations in a demanding environment.

Challenges and considerations

Slow steaming is a globally recognized best practice, yet barriers to industry-wide implementation remain. Global market pressures are a major influence: profit margins can diminish the longer it takes to transport goods, and maximizing profits frequently takes precedence over the many benefits of slow steaming. Strict port-of-call schedules can also add to operational pressures to arrive on time, yet backlogged port traffic can mean that ships travelling at maximum speed may still end up anchored for days or weeks before being unloaded.

Another considerable challenge is the absence of global regulations requiring slow steaming. Without these, industry-wide adoption may never happen. Although some companies have adopted slow steaming on an as-needed or occasional basis, none have implemented fleet-wide policies.

Given that slowing down for even partial segments of a voyage can provide significant benefits for the Arctic, the practice could be mandated in priority conservation areas identified by Arctic and Indigenous communities, such as marine mammal migratory corridors. Industry could also incorporate slower speed criteria in Arctic “green” shipping corridors (routes aimed at promoting sustainable shipping practices), further prioritizing the long-term benefits of slow steaming.

Put simply, slow steaming can be a feasible, cost-effective and immediately impactful way to make shipping more sustainable. It offers a balanced approach that meets the needs of people and industry, with no investment costs, while minimizing impacts on the climate and wildlife.

As the shipping industry increasingly integrates environmental considerations into operations, the vast and varied benefits of slow steaming must become a top priority. The case for mandating slowdown zones is strong, but ship operators don’t need to wait—when it comes to reducing speed in the Arctic, it’s time to act fast.

Sources:

AME. The Increase in Arctic Shipping 2013-2023. Arctic Shipping Status Report (ASSR) #1. March 2020. Updated Jan 2024.

D.D.W. Hauser, K.L. Laidre, H.L. Stern, Vulnerability of Arctic marine mammals to vessel traffic in the increasingly ice-free Northwest Passage and Northern Sea Route, Proc. Natl. Acad. Sci. U.S.A.115 (29) 7617-7622, https://doi.org/10.1073/pnas.1803543115 (2018).

Reynolds, GL. The multi-issue mitigation potential of reducing ship speeds. Environmental Sustainability Consultants. Nov 19th.

Pelić, V.; Bukovac, O.; Radonja, R.; Degiuli, N. The Impact of Slow Steaming on Fuel Consumption and CO2 Emissions of a Container Ship. J. Mar. Sci. Eng. 2023, 11, 675. https://doi.org/10.3390/jmse11030675

Leaper, R. (2019). The Role of Slower Vessel Speeds in Reducing Greenhouse Gas Emissions, Underwater Noise and Collision Risk to Whales. Frontiers in Marine Science.

Vanderlaan, A. S., & Taggart, C. T. (2007). Vessel collisions with whales: the probability of lethal injury based on vessel speed. Marine mammal science, 23(1), 144-156.