The scientist’s experiment was a success.
The scientist’s experiment was a resounding success. u shine a flashlight through a prism that’s why some whales in the Arctic can sing at a low frequency and have it travel over hundreds of kilometers in the open ocean
When you picture the Arctic, you probably imagine snowy landscapes, polar bears, and frolicking marine creatures, largely untouched by humans. Unfortunately, even the remote Arctic is not safe from pollution, and it’s not just the plastics and chemicals that get swept up by currents and dumped in the Arctic Ocean - although those are also not great. There’s a different kind of pollution that’s increasing in the Arctic, and it is completely invisible: noise pollution.
As there has been less and less ice in the Arctic, more and more cargo ships have been passing through that area, and their rumble is driving submarine species from their homes and making it nearly impossible for others to communicate or hunt. Understanding why noise pollution is such a problem and how we can fix it is key to protecting the Arctic’s entire ecosystem.
To be clear, noise pollution doesn’t just affect the Arctic - it’s been a growing problem all over the world for decades. These days, there are tens of thousands of merchant ships at sea every day, moving tons of important things around the world like food, oil, tech products, and clothes. But until recently, the Arctic Ocean was kind of a quiet oasis - ships mostly steered further south because the Arctic ice cover made it too dangerous to pass through.
The thing is, that’s changing now as Arctic ice melts due to climate change. More and more ships are taking shortcuts through the Arctic Circle, and ecosystems that had stayed pretty quiet are suddenly full of noise. For species that are already facing a warming ocean and reduced polar ice surface, this noise is making a bad situation even worse.
What makes this problem complicated is that noise pollution from ships comes in many forms, so it’s not as easy as just putting a muffler on the back of a boat. Their engines do make noise as they burn fuel, but different kinds of machinery are also constantly rattling against the hull, which sends vibrations into the sea. And the part of the ship that typically makes the most noise isn’t the engine itself - it’s the propeller. As the propellers turn through the water, they create bubbles that pop in a process called cavitation. And when ships are moving fast, all those popping bubbles get especially loud. You might not think of popping bubbles as especially noisy, but on some ships, cavitation can be louder than a motorcycle roaring by, and the sound is constant while the propellers are turning.
In the Arctic, there’s also one more big factor: many ships have to use icebreakers to carve a path through the frozen top layer of ocean water, and as you might guess, those icebreakers are not quiet. All this mechanical noise radiates into the sea at different frequencies, and it messes with marine life in a bunch of different ways. For one, low frequencies can travel hundreds of kilometers underwater, so the low rumble of ships becomes a part of the ambient noise of the sea. Between 2013 and 2019, noise levels produced by merchant ships doubled in some parts of the Arctic.
All this noise makes it harder for animals to communicate underwater - it’s like trying to talk to someone at a concert or in a crowded restaurant; voices just get drowned out. That’s bad news for some marine animals like the Arctic’s beluga and bowhead whales, because they use sound to communicate over dozens or even hundreds of kilometers. Whale songs are made up of a variety of noises - clicks, whistles, and pulses - although we’re still decoding exactly what it is they’re saying in these songs. But we do know that they sing at a very low frequency, which allows the songs to be heard over those long distances. In some Arctic waters, their sounds can travel especially far. That’s because sound changes speed depending on the density of the water it’s traveling through, and that density of water depends on a whole host of factors.
So as the sound waves hit layers of water with different temperatures, salinities, or even schools of fish, the sound refracts or bends, like when you shine a flashlight through a prism. That’s why some whales in the Arctic can sing at a low frequency and have it travel over hundreds of kilometers in the open ocean.