In recent news, floating robots and elephant seals joined a scientific research team to
help solve a mystery about our polar seas.
Ok, there are giant, recurring holes called polynyas that tend to pop up in both the Arctic
and Antarctic that scientists just did not understand.
And no, these aren’t caused by the regular old melting of the ice caps, they’re a long-standing,
well-documented, mysterious and surprising aspect of polar sea ice.
They’re essential to these ecosystems for many reasons and are fascinating because under
the circumstances, scientists would expect there to be a thick chunk of ice there...but
there’s not.
Instead, there’s a big hole opening into the ocean underneath.
The polynya these researchers studied in particular is an open-ocean polynya, meaning it vanishes
every summer when the sea ice melts, and SOME years it’ll randomly reappear in the same
spot when the ice reforms...But sometimes not.
We know a little bit about how these kinds of polynyas are maintained, but haven’t
known that much about how they form in the first place.
The formation of this gaping hole that has ranged from the size of New Zealand to the
size of South Carolina doesn’t seem to be related to changes in temperature, or other
factors that would seem obvious.
To explore the whole range of complex variables that could be at play in forming this polynya,
a research team at the University of Washington decided to analyze massive amounts of data
that gave them a pretty comprehensive view of both the ocean and the ice for a period
of several years.
The essential tool in making this project happen?
FLOATING ROBOTS.
These novel bots are actually a really exciting tool being used in oceanography because they
can remotely record all kinds of data: the temperature, salinity, ocean currents, and
exciting new developments in biochemical sensor technology allow them to take readings of
oxygen and nitrogen levels, acidity, and lots of other complex biological and chemical factors.
And they can dive a few kilometers below the ocean’s surface, getting readings on what
the ocean is like in the middle of winter, when it would be too expensive and even dangerous
for researchers to get there by boat.
So...why do we need the seals?
Lest we forget, temperature, salinity, and other measurements were also gathered from
elephant seals wearing sensors.
Seals have access to the same parts of the ocean that the bots do, but the seals took
data in years when the polynya didn’t show up, and there was no hole in the ice.
So the researchers could compare ocean conditions between years with and without polynyas.
As a result of all this awesome data, the researchers found that increases in salinity
and strong storm activity are likely the formative factors for this mysterious polynya.
Both storms and increased salinity cause warmer water to rise to the surface and melt a hole
in the ice.
The reason the polynya keeps forming in the same place is because of the underwater topography:
it’s right above an undersea mountain!
This traps that warm water there like a vortex, keeping this polynya from closing back up.
AND if you’re wondering what the seals thought about all this—sensors like this are attached
using a special kind of glue that lets the sensor fall off after a few months, after
which the seals can go back to their day job of just...being seals.
Polynyas—besides being mysterious puzzles to oceanographers—are essential parts of
polar ecosystems.
They provide a bridge between ice and ocean for many polar animals, like seals and penguins.
Because they let sunlight into spots in the ocean that would otherwise be covered by ice,
polynyas provide ideal conditions for phytoplankton, which are the bottom link in the marine food
chain—everything else in the ocean depends on their existence. And polynyas pour heat
and moisture out of the sea and into the local atmosphere, changing the weather of their
immediate vicinity.
And climate change is associated with a decrease in ocean salinity and increase in severity
and unpredictability of severe weather events, both of the factors that play a major role
in polynya formation.
So while the researchers don’t know if the expected changes in climate will increase
or decrease the instances of polynyas, they’re definitely pretty sure polynya behavior will
be disturbed.
Which may influence local weather patterns and ocean currents in ways that reverberate
into the rest of the world’s oceans and the wider climate patterns.
And in order to understand just how this could affect Antarctic wildlife and sea ice dynamics,
researchers say they can use results from studies like this to improve the models and
simulations that help us know what to expect, and how we can prepare.
Want to know more about what’s lurking under the ice at the bottom of the globe?
Make sure you subscribe, and check out this video on the dead continents underneath Antarctica
over here, and keep coming back to Seeker for all your ocean science news.
As always, thanks for watching and we’ll see you next time.