- Polar Sea ice is one of the most important
insurance policies against runaway climate change. It helps regulate the earth's temperature, influences global ocean circulation. And it's critically important
in protecting the ice sheets from melting and causing
massive sea level rise. But as the world warmed, something really confusing
happen in the Southern Ocean, while nearly all other ice
on earth was decreasing Antarctic sea ice levels
were mysteriously increasing. - It was a paradox, right? W
e had a warming world, but Southern Ocean sea ice was expanding and that was in contradiction
to what our models suggested. - Unlike the steady downward
trend of Arctic sea ice Antarctic sea ice records
since the late 1970s showed a nearly flat line. That's good news, right? But then they dropped and they stayed low. Reaching an all time record
low in 2023 by a wide margin And 2024 isn't looking so good either. Scientists have been
scrambling to figure out what is going on - This year. Southern
Ocean sea ice got to just over seven standard
deviations below the mean. You would expect to see something like that once every 700 billion
years, which is just bonkers. - The change has even been noticeable to scientists working
in Antarctica. There's - Been a real lack of sea ice around Antarctica. It's really alarming - What they were seeing broke all of their climate models and their findings had them questioning. If Antarctica is
experiencing a state change, - You don't need statistics to t
ell you something different
was happening this year, and it was a big difference. - And Arctic sea ice is
critically important for the globe as a whole, and some of our most iconic species depend on it, including emperor penguins. The ancestors of this
flightless bird roam the earth millions of years ago during
the age of the dinosaurs. And they live through
some pretty incredible changes in climate. But the threats they face
today are unprecedented and their future is precarious. There are actu
ally pretty
good projections about how their population
will fare under different warming scenarios. So keep watching to find out
what we can expect by the end of the century and how emperor
penguins may be a harbinger for what's to come. Antarctica has ice both on
land in the form of ice sheets and in the waters around it, in the form of seasonal sea ice. Like in the Arctic, the surface of the ocean around Antarctica freezes
over in the winter and melts in the summer. - At its summer minimum, i
t covers an area about
half the size of Australia. And then in autumn winter this freezes and it covers an area two and a half times the size of Australia. So we've got this huge area of sea ice. This seasonal waxing and
waning as there's more and less sunlight,
warmth over the southern ocean is really reliable. - But the stability of the system was thrown
into question in 2016 while scientists were busy trying to figure out why sea ice
appeared to be increasing, something shifted dramatically -
Then in in 2016, in our study, we find that there's this abrupt
decline in sea ice in a space of two years. The Antarctic lost as much sea ice as the Arctic lost in
three decades, right? It's an really abrupt drop. - That was a huge shock to the community. We didn't see it coming. - The following year
showed signs of increasing, but we're still
consistently below average. But then 2023 happened - This summer was a record low. The previous summer was a record low, so we had two record low
summer
s back to back. And then this winter has been
completely unlike anything else we have seen in the records. It's also unlike anything
in the reconstructions. We were missing an area of ice about two and a half million square
kilometers in size. So that's an area the size of
Alaska and Texas put together. It's a vast, vast area of the ocean that would normally be covered
by ice that wasn't this year And even though Antarctica
feels incredibly far away when its sea ice melts, it has cascading effec
ts. - Albedo means reflectivity. So if we think about an ocean
surface covered in sea ice, the sea ice is white, and
so it's highly reflective and incoming sunlight
is reflected from the ice back to space. And so it helps keep the
surface of the earth cool. And so this is one of the important roles that sea ice plays in
regulating global climate. Another one is in
influencing the deep ocean circulation. Sea ice forms when the surface of the ocean it freezes and the ocean is salty. Some of this s
alt is taken up into the sea ice, but some of it isn't. And this extra salty brine is actually rejected from the bottom of the sea ice. When the sea ice is freezing
and this really dense heavy water, it circulates around
the shelf around Antarctica and some of it sinks into the deep ocean and it forms this, this
deep ocean circulation, - This deep overturning ocean
circulation travels the entire globe and takes over a thousand
years to complete its cycle. It's hugely important
in the ocean's abi
lity to uptake carbon and absorb the excess heat that burning fossil fuels has created. It slowing down has huge consequences for our planet's climate. - And finally, sea ice - it physically protects the Antarctic coast and the ice shelves, but when
sea ice is absent, that waves, they break on the ice shelves and they can break up the ice shelves faster than they other otherwise would. Once we have these ice
shelves collapsing, this means that the Antarctic ice sheet, the ice that sits on the co
ntinent, can
slide into the oceans faster and this will raise global sea levels. - Scientists have estimated that the Antarctic ice
sheets hold enough ice to raise sea levels by
58 meters if they were to completely melt. Fortunately, that's unlikely
to happen anytime soon, but West Antarctica alone
could add over seven inches of sea level rise by 2100. So - Even though Antarctica
is really far away, and even we might not ever go there, it can affect our global sea levels. It can affect our globa
l climate - And it's home to some of
our most iconic creatures, including the emperor penguin. - Emperors are such cool
birds, you know, I mean they, they, they are remarkable. They are incredibly gregarious.
They love each others company. The individuals obviously
realize that their chances of partaking in reproductive
activities is very limited. You have to mate, and you have to lay your
egg at a certain time because if you don't,
you are missing out on an entire breeding season. - And emperor
penguins lay just one egg. The egg can't survive on the cold ice. So the female very carefully
transfers it to the male who will incubate it for
over two months, fasting that entire time. In addition to the time it took to arrive at the colony and mate. These birds do not build nests. There is no nesting material. They have to incubate
their eggs on their feet. That means that they
cannot be on very steep or very uneven ground. - There are two main types of sea ice. Pack ice is any type of
sea
ice that's floating, not attached to land. It can drift around and
form large dense ice floes, but it's a dynamic environment
that's moving, breaking up and shifting, which is not
a good place to lay an egg. Then there's the fast ice. It's also sea ice that forms
on the surface of the ocean, but it's fastened to the shoreline. It tends to be thicker up
to two meters in the winter, - And that is precisely where
emperor penguins need to be. - Once the egg hatches the
mother returns from feeding at
sea. For the next five months, the mother and father will take turns waddling up to 100 kilometers over
the sea ice to get food for their chick in the open waters. But if the sea ice where the chicks are
nesting disappears too soon, the results can be catastrophic. - We had this awful situation
in November last year where the sea ice that the
emperor penguins were breeding on actually melted away before the penguin chicks
were ready to swim. This resulted in catastrophic
breeding failure of of
four out of five penguin colonies that are in a particular region where sea ice was very low. And what we know is that
if sea ice keeps declining the outlook for these emperor
penguins, it's really bad. - Emperor penguins have lived
in this very, very dynamic and and hostile environment
for a long, long time. These sort of events in general probably happened in the past. They, they have the ability, as they have demonstrated
several times in our days, that they can shift location. But what is so
frustrating is that it's happening more frequently and it is happening to more colonies and eventually they're just
going to run out of options. - These penguins only lay one egg a year. So breeding failure year after year has huge
consequences for the population. Studies have found that more than 90% of emperor penguin colonies
could face quasi extinction by the end of the century. But is all of this temporary? We know that Antarctica
is a dynamic environment and it can be hard to see
trends t
hrough all of the noise Because the continent
itself is in the way, sea ice in Antarctica forms
mostly at warmer latitudes, meaning it's younger and
thinner than Arctic sea ice. It's distributed around the
entire edge of the continent and it's heavily influenced by wind, waves and weather. Natural cycles
mix with climate change to really confuse the
picture of what's happening. So perhaps these eight years of lower sea ice are just a blip and the line will level out again. - There is some eviden
ce
that sea ice does go through these decadal cycles. And so it could be that we're in this, this natural cycle where sea ice is low. Scientists look back at
those high sea ice years to try to find clues. - There was some hypotheses about, maybe it's the melt water
coming off the ice sheet of Antarctica, and that
fresh water sits on top of the ocean, sort of seals
off the heat in the deep ocean from affecting the ice. There was some theories about
the ozone hole changing the way the winds worked
and the ocean transport. - But I think the wide consensus is, is the main contributor was the winds. Sea ice is really affected by the wind and wind changes were
causing more sea ice to form. - But that didn't seem to explain the low sea ice
years we're seeing. Now, - The other thing that we know
is that the ocean is warming. The Southern Ocean is warming because we are emitting greenhouse gases and we are causing global warming. And what we found is that
whereas the atmosphere was really impor
tant in driving sea ice
in the high sea ice state, we're now seeing a lot stronger influence of the ocean in this low sea ice state. And so, you know, it sounds
pretty obvious to say that, that the warm ocean is
melting the sea ice, but this wasn't always the case. And I guess what this points to is that now sea ice is being
influenced in a different way than it was previously. - So is this the new normal? - Something has so fundamentally
changed in the climate system that it's not just an aberr
ation, it's not just a a couple of
years of strange anomalies. This is the new state, and that's what we expect
to see for the future. Or perhaps it's gonna change again and we're gonna end up
in an even newer lower state of sea ice. - 2023 shook our understanding of climate change all around the world. We collectively experienced
heat waves, storms, wildfires like never before. And 2024 isn't shaping
up to be much better For emperor penguins, there's a big difference between the ambitious 1.5 d
egree goal, the current trajectory of 2.6 degrees and the unmitigated
4.3 degrees of warming. Perhaps this state change
towards a new level of lower sea ice. And the massive failure of
penguin colonies will serve as an alarm and motivation for humanity to halt human caused warming and to adapt to the
inevitable changes ahead. But what do you think? Let us know in the comments
below before you go. Have you noticed all the
great new shows here on Terra? Animals, climate change, food science... It'
s like a festival of science. I specifically wanna talk
about Fascinating Fails, which tells the stories of how some of science's biggest
discoveries were actually made by mistake. You'll hear about everything
from antibiotics to plastics to the Big Bang. There's a link in the description.
We hope you check it out. And if you do, let them know
that Weathered sent you.
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