How climate change is altering the underwater soundscape | Kate Stafford | TEDxCERN

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The underwater isn't silent, it's as noisy as any jungle or rainforest, but climate change is dramatically changing the soundscape so the impact on the planet could be cataclysmic.

Oceanographer Kate Stafford takes us on an auditory and visual journey, from the depths of the ocean and up to the surface with a clear message: to develop local solutions to reduce human-caused underwater noise.

In 1956, a documentary by Jacques Cousteau

won both the Palme d'Or
and an Oscar award.

This film was called
"Le monde du silence,"

or "The silent world."

The premise of the title was
the underwater world was a quiet world.

We now know, 60 years later,

that the underwater world
is anything but silent.

Although the sounds
are inaudible above water,

depending upon where you are
and the time of year,

the underwater soundscape can be
as noisy as any jungle or rain forest.

Invertebrates, like snapping shrimp,
fish, and marine mammals all use sound.

They use sound to study their habitat,

to keep in communication
with each other, to navigate,

to detect predators and prey.

They also use sound by listening
to know something about their environment.

Take, for an example, the Arctic.

It's considered a vast,
inhospitable place,

sometimes describes as a desert,

because it is so cold, and so remote,
and ice-covered for much of the year.

Despite this, there is no place on earth
that I would rather be than the Arctic.

Especially as days lengthen
and spring comes.

To me, the Arctic
really embodies this disconnect

between what we see on the surface,
and what's going on underwater.

You can look out across the ice
- all white, and blue, and cold -

and see nothing.

But if you could hear underwater,

the sounds you would hear
would at first amaze and then delight you.

While your eyes are seeing nothing
for kilometers but ice,

your ears are telling you that out there

are bowhead and beluga whales,
walruses, and bearded seals.

The ice too make sounds.

It screeches, and cracks, and pops,
and groans as it collides and rubs

when temperature,
or currents, or winds change.

And under 100% sea ice,
in the dead of winter,

bowhead whales are singing.

You would never expect that,

because we humans,
we tend to be very visual animals.

For most of us, but not all,

our sense of sight is
how we navigate our world.

For marine mammals that live underwater,

where chemical cues
and light transmit poorly,

sound is the sense by which they see.

Sound transmits very well underwater,
much better than it does in air.

So signals can be heard
over great distances.

In the Arctic, this is
especially important

because not only do Arctic marine mammals
have to hear each other

but they also have to listen
for cues in the environment

that might indicate
heavy ice ahead or open water.

Remember, although they spend
most of their lives underwater,

they are mammals,
so they have to surface to breathe.

They might listen for thin ice or no ice

or listen for echoes off nearby ice.

Arctic marine mammals live in a rich
and varied underwater soundscape.

In the spring, it can be
a cacophony of sound.

(Buzzing, whizzing, squeaking,
whistling, wailing sounds)

But when the ice is frozen solid,

and there's no big temperature shifts
or current changes,

the underwater Arctic has
some of the lowest ambient noise levels

of the world's oceans.

But this is changing.

Climate change and decreases
in sea ice are also altering

the underwater soundscape of the Arctic,

which is a direct result
of human greenhouse gas emissions.

We are, in effect, with climate change,

conducting a completely
uncontrolled experiment with our planet.

Over the past 30 years,

areas of the Arctic have seen
decreases in seasonal sea ice

from anywhere
from six weeks to four months.

This decrease in sea ice
is sometimes referred to

as an increase in the open water season,

that is the time of year
when the Arctic is navigable to vessels.

Not only is the extent of ice changing

but the age and the width of ice is too.

You may well have heard
that a decrease in seasonal sea ice

is causing loss of habitat
for animals that rely on sea ice

such as ice seals,
or walruses, or polar bears.

Decreasing sea ice is also causing
increased erosion along coastal villages

and changing prey availability
for marine birds and mammals.

Climate change and decreases
in sea ice are also altering

the underwater soundscape of the Arctic.

What do I mean by soundscape?

Those of us who eavesdrop
on the oceans for a living

use instruments called hydrophones,
which are underwater microphones.

We record ambient noise,
the noise all around us.

The soundscape describes
the different contributors

to this noise field.

What we are hearing on our hydrophones

are the very real sounds
of climate change.

We are hearing these changes
from three fronts:

from the air, from the water,
and from land.

First: air.

Wind on water creates waves.

These waves make bubbles,
the bubbles break.

When they do, they make noise,

and this noise is like a hiss
or a static in the background.

In the Arctic, when it's ice-covered,

most of the noise from wind
doesn't make it into the water column

because the ice acts as a buffer
between the atmosphere and the water.

This is one of the reasons that the Arctic
can have very low ambient noise levels.

But with decreases in seasonal sea ice,

not only is the Arctic now open
to this wave noise

but the number of storms
and the intensity of storms

in the Arctic have been increasing.

All of this is raising noise levels
in a previously quiet ocean.

Second: water.

With less seasonal sea ice,
sub-Arctic species are moving north

and taking advantage of new habitat
that is created by more open water.

Arctic whales, like this bowhead,
have no dorsal fin.

because they have evolved
to live and swim in ice-covered waters.

Having something sticking off of your back

is not very conducive
to migrating through ice,

and may, in fact, be excluding
animals from the ice.

But now, everywhere we've listened,
we're hearing the sounds

of fin whales, humpback whales,
and killer whales,

further and further north

and later and later in the season.

We are hearing, in essence, an invasion
of the Arctic by sub-Arctic species,

and we don't know what this means.

Will there be competition for food
between Arctic and sub-Arctic animals?

Might these sub-Arctic species introduce
diseases or parasites into the Arctic?

What are the new sounds
that they are producing

doing to the soundscape underwater?

Third: land.

By land, I mean people.

More open water means
increased human use of the Arctic.

Just this past summer,

a massive cruise ship made its way
through The Northwest Passage,

the once mythical route
between Europe and the Pacific.

Decreases in sea ice have allowed humans
to occupy the Arctic more often.

It has allowed increases
in oil and gas exploration and extraction,

the potential for commercial shipping,

as well as increased tourism.

We now know that ship noise increases
levels of stress hormones in whales

and can disrupt feeding behavior.

Air guns, which produce

loud, low-frequency 'whoomps'
every 10 - 20 seconds,

change the swimming
and vocal behavior of whales.

All of these sound sources
are decreasing the acoustic space

over which Arctic marine mammals
can communicate.

Arctic marine mammals
are used to very high levels of noise

at certain times of the year,

but this is primarily
from other animals or from sea ice.

These are the sounds
with which they've evolved,

and these are sounds
that are vital to their very survival.

These new sounds are loud,
and they are alien.

They might impact the environment
in ways that we think we understand,

but also in ways that we don't.

Remember, sound is the most
important sense for these animals;

and not only is the physical habitat
of the Arctic changing rapidly

but the acoustic habitat is, too.

It's as if we plucked these animals up
from the quiet countryside

and dropped them into a big city
in the middle of rush hour.

They can't escape it.

So what can we do now?

We can't decrease wind speeds

or keep sub-Arctic animals
from migrating north,

but we can work on local solutions
to reducing human-caused underwater noise.

One of these solutions
is to slow down ships

that traverse the Arctic,

because a slower ship is a quieter ship.

We can restrict access
in seasons and regions

that are important for mating,
or feeding, or migrating.

We can get smarter about quieting ships

and find better ways
to explore the ocean bottom.

The good news is there are people
working on this right now.

But ultimately, we humans
have to do the hard work

of reversing, or at the very least,

decelerating human-caused
atmospheric changes.

So let's return to this idea
of a silent world underwater.

It's entirely possible

that many of the whales
swimming in the Arctic today,

especially long-lived species
like the bowhead whale

- that the Inuit say
can live two human lives -

it's possible that these whales
were alive in 1956

when Jacques Cousteau made his film.

In retrospect, considering all the noise
we are creating in the oceans today,

perhaps it really was "The silent world."

Thank you.

(Applause)