The ocean is a symphony of sounds...
at least where they can still be heard.
We humans have made the sea noisier than ever before.
And the way things are going, the underwater world is set to become one thing:
Even louder!
With devastating effects on marine life.
"From feeding to predator avoidance, sensing their environment,
food finding, reproduction, the whole thing!
But there are ways to reduce man-made noise.
Like bringing water and sound into motion through vibration
or by using bubbles as insulation.
Let's explore some smart ways to turn down the volume in the ocean.
And find out why this might also be good for the climate.
"These divers, wearing the compressed air aqualung,
are true space men.
To make this film, they roamed deep under the Mediterranean,
the Red Sea and the Indian Ocean.
In a mysterious realm, a silent world."
This is a documentary film from 1956, by marine biologist Jacques-Yves Cousteau.
It's called "The Silent World" –
which is actually a pretty bad title.
Today we know, even without human impact,
the ocean is anything but silent.
The friction of the wind on the open sea also makes noise under the surface.
As do the rumbling of icebergs or waves that crash into the water.
Underwater sound travels extremely fast,
and up to thousands of kilometers.
Sound is essential for almost all marine animals –
from whales to jellyfish.
"I really have to say, sound is used so predominantly,
it is the most predominant sense for actually all marine life."
This is Lindy Weilgart, she's a biologist
specialized in the effects of noise pollution on marine life.
Animals use sound to communicate, to navigate,
to find mating partners or prey.
Clownfish, for example, use it to make clear who's the boss –
mostly females by the way.
They produce the sound when their teeth clash as they rapidly slam their jaws shut.
This little cleaning shrimp advertises its services to reef fish by clapping.
And some coral reef fish were found to listen
carefully to the sounds coming from a reef
in order to decide whether it's healthy enough
to provide for their next offspring.
But hearing what fish need to hear...
is getting more and more difficult or even impossible.
Even though it's hard to compare sound levels
in the water with those on land,
we do know one thing:
Some marine life is currently exposed to noise levels
that can literally destroy their sense
of hearing, literally render them deaf or kill.
Human activities make some animals stop singing,
eat less, feel stressed and look out for danger
instead of taking care of their offspring or finding a mate.
"It's like you're walking around in a fog.
That's a pretty serious effect too for animals
that depend on sound so much."
So why are the oceans becoming so noisy?
One factor is offshore wind farms.
Generally, of course, wind energy is part of the solution.
To reach our climate targets we have to install 150,000
new offshore wind turbines by 2050 worldwide.
But installing these offshore turbines creates
a hell of a lot of noise!
In the North Sea, it used to damage the hearing of porpoises,
scaring them away from their feeding and breeding grounds
many kilometers from the construction sites.
"The foundations are most likely big steel piles,
and they must drive into the seabed
by hammering or impact pile driving.
And this causes underwater noise, which is more or less
comparable as a starting aircraft [on shore]."
This is Michael Bellmann,
his company audits and advises
businesses as to how they can cut
their underwater noise pollution.
The sounds emitted by a pile smashing into the sea floor
travels kilometers from the source.
But these little air bubbles can help.
Compressed air flows through those tubes.
They lie on the ocean ground around the piles,
creating bubbles which rise to the surface,
forming a tight insulation curtain.
The bubbles reflect the sound back to where it came from and disperse it.
Fewer soundwaves actually cross the curtain, which leads to a 90 percent reduction in volume.
This means a much smaller area is affected,
and with it, far fewer marine animals.
This is how it sounds in action WITHOUT an air bubble curtain.
And WITH an air bubble curtain.
"The challenging issue is that you have to
live with the offshore conditions, wind, waves,
weather conditions, currents and so on."
If wrongly applied the curtains are useless.
They also can't turn off the hammering entirely
and for sensitive animals even the reduced
amount of noise is still far too much.
Thanks to tighter regulations, however,
the curtains are now almost standard for offshore
constructions in the German North Sea.
And interest is picking up in the U.S,
the Netherlands and Taiwan too.
And that's understandable, because environmental
protection comes cheap here.
The costs of implementing bubble curtains
during construction are just 1% or less of
the total investment needed for an offshore wind park.
Ok, wind turbines are one thing, but here's a bigger problem:
container ships.
The ocean is full of vessels.
There are more than 5000 merchant
vessels on the seas right now.
Over the past 50 years, there has been an estimated
32-fold increase in noise along major shipping routes.
Shipping is by far the main source of
noise pollution in our oceans.
Let's take a look at the port of Boston.
All those green dots are the sound footprints of whales –
many of whom may be talking to each other.
And this, this and this are all huge vessels
drowning out the communication between the whales.
The culprit, and the potential solution, is this:
the ship's propeller.
You maybe know this kind of pressure pot.
It works by controlling the steam pressure inside it,
pushing up the temperature at which water boils.
This results in higher heat
that cooks the food more quickly.
On a ship's propeller the OPPOSITE happens.
Not with food but with the water.
It's called cavitation.
"Due to the fast motion
of that propeller through the water
locally, the pressure is extremely low,
so that at ambient temperature, the water boils
and creates bubbles – creates vapor bubbles,
and these bubbles grow and these bubbles
shrink and collapse."
This is Max Schuster.
He's a naval architect who advises
big shipping companies on
how to lower their vessels' noise.
Once the steam bubbles are released from the
low-pressure zone around the propeller,
they burst with a big bang,
creating noise levels comparable
to a rock concert on shore.
The good news is that, in theory, this is at least
partly fixable – and in a way that
would be good for the climate
– and the pockets of big shipping companies, too.
Basically it's like this:
fewer bubbles on the propeller
can mean less fuel consumption.
In 2017, Danish shipping company Maersk retrofitted
the propellers and engines of five vessels,
primarily to save fuel.
But their sound emissions also dropped by 75%.
This add-on device improves a vessel's flow in the water,
which means less cavitation, less damage to the ship,
less noise and fuel savings up to 8 percent,
according to its producer.
But installation doesn't come cheap – and shipping companies
are rarely obliged to make the changes.
With current cargo prices high, companies prefer to
keep ships in operation, rather than investing in a retrofit.
"For many ships there could be savings possible,
especially due to the fact that each ship
needs to go to dry docking each
four to five years for other purposes.
And that could be a chance to install
these energy saving options."
And then there is another option:
reducing speed.
If ships were to slow down only 10%,
they'd save significant amounts of fuel and emissions,
and their acoustic footprint could be halved.
To incentivize ship operators, the Port of Vancouver
has cut port charges for certified,
quieter vessels by as much as half.
And here's the chief offender.
Do you know what this is?
A seismic air gun.
The fossil fuel industry uses them to
locate new oil and gas fields in the ocean.
Their sound waves are as loud as a spacecraft
and can be heard hundreds of kilometers from the source,
crossing entire oceans.
For days, sometimes even weeks or months,
these tubes fire compressed air:
every 10 seconds.
The way the sound is reflected gives an indication
of the seafloor's geological profile.
At the same time, with every blast,
two thirds of all zooplankton larvae
within a kilometer of the explosion drop dead.
These tiny animals are super important for
ALL life in the oceans.
They are an irreplacable part of the food chain –
and ensure the health of its ecosystems.
"Air guns are incredibly wasteful.
They're way too loud for what they need to do.
What affects a whole lot of species –
like the dolphins and porpoises, and the
beaked whales I mentioned,
and they would not need to be affected at all."
These machines have been plowing through the oceans since the 1960s.
Today there are 12000 offshore oil and gas operations globally.
Ironically, the fossil fuel industry itself is
conducting research on more environmentally-friendly methods for their surveys.
One technique is called marine vibroseis,
which creates the required signals with vibration
instead of an explosion.
It uses low, constant and controllable frequencies.
A hum, if you will, instead of a big blast.
"An airgun is so strong it could rip your arm off,
whereas a vibroseis on land you could put an egg
underneath it and it won't break."
So far there is little research on marine vibroseis.
But initial models suggest that its damaging
effect on whales and dolphins would be just
10% of that of an air gun.
The investing companies like ExxonMobil, TotalEnergies
and Shell maybe have their eye
on another advantage, though:
The marine vibrator can also map oil and gas in shallow waters
close to coasts, where air guns have so far been useless.
But this just sounds absurd, doesn't it?
More sustainable methods to find more fossil fuels?
"We really should not be
searching for oil and gas under the ocean anymore.
We really need to make this green transition.
That's the main solution."
There are plenty of options for reducing noise pollution in the oceans.
But worldwide insufficient regulations
are in place to encourage the shift.
In 2011, Germany put one of the world's first
noise limits in place to protect North Sea
marine life from the effects of offshore wind park construction.
Today air bubble curtains are standard there
and the industry is doing fine.
Taiwan is now introducing a similar regulation.
"I think the impact on environment is incredibly high.
So, I expect it's the right way forward to say
we have to define what is
a good environmental status.
Proving an exact sound threshold
for individual ecosystems is difficult
and when it comes to the economy,
leaders don't want to be more restrictive than absolutely necessary.
But without incentives or regulation, the industry has
little reason to be quieter at all.
"It's a doable problem as long as governments are
happy to tackle it, and it does have to be done on a global scale,
because sound travels so far and so fast.
We absolutely know quieter is better."
"What do you think?
What should we do to mitigate ocean noise?
Tell us in the comments and
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