The environmental cost of XXL ships

Much of what surrounds us at any given moment – whether a product, a commodity or a raw material – was once on a ship. To travel from their place of origin to their point of use or consumption, these goods embark on seaborne journeys around the globe. This occurs thousands of times a day on tens of thousands of vessels moving from port to port. Ships manage approximately 90 percent of global trade, transporting nearly 11 billion tons of goods each year.
This happens because oceans, which cover the majority of the Earth’s surface, offer relatively unobstructed pathways for both passengers and cargo ships traveling between continents. Sea routes are strategically chosen for their economic efficiency in linking lands and one of the most significant sea routes is the North Atlantic Ocean route, which Energy Observer is currently covering. This route has the highest traffic among all ocean routes: nearly two thirds of the global number of ships and cargo volume navigate this route, linking ports of Western Europe with those on the east coast of North America since its opening in 1840.

Whether the importance of such a sector is evident and widely known, its impacts are often poorly understood.

To keep pace with the expanding global economy, the total loading capacity of ships nearly quadrupled between 1996 and 2020. Newer, bigger, and faster vessels have been added to the fleet and this trend shows no sign of slowing down. Unfortunately, bigger ships mean bigger impacts. With faster ships comes higher underwater noise: according to scientists, noise levels in the oceans are doubling roughly each decade.
Today, a cargo ship emits about 190 decibels, exceeding the noise of a jet engine at take-off. Most of this acoustic pollution comes from propellers’ cavitation, a phenomenon that, in addition to noise, results in a loss of energy efficiency. In addition, sound travels much faster in water than in air – around four times faster – which means it can travel great distances and impact a large portion of the ocean.

Now, sound is the very lifeline of the ocean. From whales to dolphins, countless marine species rely on sound for survival: they use it to communicate, to find food or avoid predators, to reproduce or to orient themselves. Like ships’ sonars, some animals can use sounds to detect, locate and characterise objects. Anytime ship noise drowns out natural sounds, marine animals are forced to adapt: some flee their habitat, others struggle to feed and nurse their babies, and most experience high levels of stress.
The good news is that this impact can be easily reduced. Changes can be made to the design of the ship’s propellers and hull, but there is an even simpler solution: slowing down. Every knot of speed reduction translates into a 1 decibel decrease in noise.

Read the full article on the Energy Observer website.