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Something Strange Is Happening Under the Doomsday Glacier - Video học tiếng Anh
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Something Strange Is Happening Under the Doomsday Glacier
Something Strange Is Happening Under the Doomsday Glacier
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Субтитры (210)
0:00
Antarctica is home to more than you might think.
0:02
Harsh winters, waddling penguins, research stations, blubbery seals, and, um...
0:09
oh yeah, the Doomsday Glacier.
0:11
This glacier is enormous, and making sure it stays that way
0:15
is crucial for preventing irreversible sea level rise.
0:18
It probably won’t surprise you to hear that it’s shrinking.
0:21
But the reasons it’s shrinking are a lot more complicated than the one you’re imagining.
0:26
So complicated that we’ve only recently begun to understand all of them.
0:29
The good news is that, with these findings,
0:32
there’s a real chance we can slow down the melting.
0:35
Which is desirable for something with “doomsday” in the name.
0:38
[♪ INTRO]
0:42
While “Doomsday Glacier” is super catchy,
0:45
scientists much prefer to call it by its proper name: Thwaites Glacier.
0:49
It’s named after Fredrik Thwaites, a glacial geologist and geomorphologist.
0:53
He never actually visited the glacier, but he was
0:55
so influential in the field of glacial geology that they named it in his honor.
0:59
It was discovered in 1947, and it’s the single widest glacier in the world,
1:05
with an area of 192 thousand square kilometers.
1:09
Or, to put it another way, larger than the entire American state of Florida.
1:14
A lot colder than Florida, too.
1:15
And I am manifesting that it is gonna stay that way!
1:18
Thwaites Glacier is also very tall.
1:21
The ice is 800 meters deep at its thinnest, and almost 4000 meters at its thickest!
1:27
For comparison, the world’s tallest building, the Burj Khalifa, is only 828 meters high,
1:34
so parts of the glacier would bury it in ice several times over, with room to spare.
1:39
The glacier is so big that when a big chunk breaks off,
1:42
the tremors from the falling ice can be detected by seismometers as far as 1600 kilometers away.
1:48
And it picked up its ominous nickname, the Doomsday Glacier, because if it ever melts
1:53
or breaks apart, all the water locked up in there could cause dramatic sea level rise.
1:59
But let’s go back a bit to review what a glacier is,
2:02
in case you slept through your 8am section of Glaciers 101.
2:05
Glaciers come in two different flavors.
2:07
If you hike, the type you might be familiar with are alpine glaciers.
2:11
They form in chilly mountain regions and most of them flow down into valleys like a river of ice.
2:16
And then there are ice sheets, like the Thwaites Glacier.
2:20
Instead of flowing in one direction,
2:21
they form domes that flow in all directions, emptying out into the sea.
2:26
This distinction is important because Antarctic
2:28
glaciers rest partially on land, and float partially on the sea.
2:32
That land vs sea ratio is critical for understanding
2:35
a glacier’s potential impact on sea level rise.
2:38
See, if ice is already floating in the ocean, like an iceberg,
2:42
and then it melts, that doesn’t really affect the overall sea level.
2:46
Think about it like a glass of ice water.
2:48
No matter how full your glass is, it won’t overflow when the ice eventually melts.
2:52
But if you add more ice cubes, eventually the glass would overflow.
2:56
As long as glacier ice is locked up on land, their extra water isn’t overflowing our oceans.
3:02
But as the world warms, glaciers like Thwaites are flowing faster and faster toward the sea,
3:07
transporting all that ice to the ocean.
3:09
To be specific, estimates say that if the Thwaites Glacier melts,
3:13
it alone could raise global sea levels by as much as 65 centimeters.
3:17
That’s more than double the amount that sea levels have already risen since we started keeping track.
3:23
Which is pretty bleak.
3:24
But believe it or not, that’s not the most “doomsday” thing about the Doomsday Glacier.
3:29
What scientists are really worried about is that losing the Thwaites
3:33
Glacier might also destabilize the West Antarctic Ice Sheet.
3:37
This ice sheet contains enough ice to raise sea levels by several meters,
3:42
which would be enough to flood almost all of Florida’s coastal cities.
3:46
Orlando would nearly be beachfront property!
3:48
The Thwaites Glacier is one of the only things holding the West Antarctic Ice Sheet in place.
3:53
So losing the Thwaites could make the West Antarctic Ice Sheet fall into the sea too.
3:58
Despite this very real danger, many scientists don’t like the ‘Doomsday’ nickname because it
4:03
makes it seem like we’re already doomed and there’s nothing we can do to stop it.
4:07
Which is absolutely not what scientists are saying.
4:10
There’s still a lot we could do to slow down
4:12
climate change if we could just get our collective act together!
4:15
The glacier is shrinking, but panicking about it isn’t useful.
4:19
Scientists still don’t know enough to predict a time of death for Thwaites Glacier.
4:24
Because this whole thing is a little more complicated than a cooler full
4:27
of ice cubes melting during your backyard cookout.
4:29
Thwaites Glacier is a complicated system.
4:32
It has a lot of different forces acting on it,
4:34
and we don’t fully understand how all those forces affect each other.
4:38
So it’s hard to predict exactly how much the glacier is melting,
4:41
or how it will react to future temperature changes.
4:44
But before we tell you what we do know about this glacier, we’ve gotta run a quick ad.
4:50
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4:53
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4:55
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4:57
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5:23
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5:28
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5:39
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5:43
To start with, Thwaites is always moving.
5:46
That’s the nature of a glacier, but Thwaites likes to keep us on our toes.
5:50
A research paper from 2022 showed that rather than
5:53
sliding smoothly towards the ocean, Thwaites tends to retreat in spurts.
5:58
Glacial retreat happens when a glacier shrinks faster than it gains new snow and ice.
6:04
Its terminus, the edge point, ends up moving uphill.
6:07
And researchers were able to track Thwaites Glacier’s
6:10
retreat by looking at sedimentary ridge deposits.
6:13
As glaciers flow, they scrape up a layer of rock and dirt and add that to their ice river.
6:19
All that stuff gets transported to the edge of the glacier and forms a small hill of sediment.
6:24
A sedimentary ridge deposit, if you will.
6:26
That means these ridges mark the end of the sediment conveyor belt.
6:30
AKA the point where the glacier broke off from the sea floor and started to float,
6:35
called the grounding line.
6:37
As the glacier retreats, its grounding line retreats, too, stepping closer to the shore.
6:42
Researchers found Thwaites’ grounding lines by swimming around under the glacier with an
6:47
autonomous underwater vehicle, basically a robot with a sediment-seeking mission.
6:51
They found a pattern of rapidly retreating spurts, occurring over the past two centuries.
6:56
And, probably unsurprisingly, they found that these spurts have been
7:00
getting closer and closer together over time.
7:02
This isn’t just because the ocean is getting warmer though.
7:05
It also has to do with the glacier’s geography.
7:08
On one end, Thwaites is pinned in place by the Thwaites Ice Shelf,
7:12
the floating section of the glacier that’s attached to the grounding line.
7:15
But on the other end, the glacier is unprotected.
7:18
It used to be shielded by the Thwaites Glacier Tongue, a narrow,
7:22
floating extension of the glacier that extended far beyond the land.
7:25
But over the past couple decades, the tongue has broken off into several icebergs,
7:30
leaving the rest of the glacier more vulnerable and less stable.
7:33
One of the largest icebergs, B-22, broke off in 2002.
7:38
B-22 is approximately the size of Rhode Island.
7:41
But that’s only like one fiftieth of the size of Florida.
7:44
Just in case you were wondering.
7:46
After B-22 detached, its largest portion, B-22A,
7:50
broke off and got grounded about 100 kilometers offshore from the Tongue.
7:54
This turned out to be a good thing, because like ice in your drink at that backyard cookout,
7:59
the iceberg managed to keep the surrounding water cooler than it would have been otherwise.
8:04
B-22A was stuck there for a really long time.
8:07
Like weirdly long for an iceberg.
8:09
It started to move again in 2022.
8:12
Since then, the tongue has split into several more icebergs.
8:15
The latest iceberg, B-22J, was spotted in September 2025.
8:20
So those are the big changes to the Thwaites,
8:23
but there have also been smaller, less visible changes beneath the surface.
8:28
When glaciers melt, they release cold, fresh water into the sea.
8:32
This can have a few strange effects, because it changes the water’s density.
8:36
It’s tempting to imagine the ocean as one uniform blob of water.
8:40
But if you had special goggles that could see density,
8:43
you’d find the ocean is actually made of many different small blobs with differing density.
8:49
The denser water sinks below the less dense bits,
8:52
like the wax in your lava lamp that sinks as it cools.
8:55
When it comes to seawater,
8:57
there are two main factors that affect its density: temperature and salinity.
9:01
Cold water is denser than warm water, but salty water is denser than freshwater.
9:07
While Antarctic seawater isn’t exactly warm, it is warmer than glacial melt.
9:12
But it’s also saltier than glacial melt.
9:15
So when cold, fresh water enters the warmer, salty water, strange things happen.
9:21
If you were looking at it with your density goggles,
9:23
you’d see some really weird lava lamp shenanigans going on.
9:27
For example, in 2013 a network of subglacial lakes drained out from underneath Thwaites Glacier.
9:34
The sudden influx of all that fresh lake water started mixing with the seawater,
9:39
creating pockets of warm saltwater suspended in the flow of cold freshwater from the glacier.
9:44
And some scientists think that when these pockets of warm water are held up
9:48
against the glacier’s surface, they can trigger faster melting at those spots.
9:53
But that’s only one possibility.
9:55
While we know a subglacial lake drained, and we know that it caused some mixing,
10:00
we can’t actually quantify the full effect of that mixing.
10:03
There’s also evidence that hurricane-like underwater storms could accelerate melting.
10:08
When water masses of different densities smash into one another,
10:12
they create storms of swirling water.
10:14
The vortices can be up to 10 kilometers wide,
10:17
and like hurricanes, they carry a lot of power and momentum.
10:21
When they reach an ice sheet floating on top of the water,
10:24
like the free edge of the Thwaites Glacier, they can slide under the ice.
10:29
When the storm gets trapped under an ice shelf, its whirling pulls cold water away
10:34
from the glacier, and draws warm water up towards the ice from the deep ocean,
10:39
effectively melting the ice shelf from the bottom up.
10:41
And since these storms are caused by the collision of water masses of differing temperatures,
10:47
that meltwater can flood out into the ocean and spin off even more vortices.
10:52
Scarily similar to how surface melting can trigger a feedback loop,
10:56
the underwater melting can build stronger storms that lead to even more melting.
11:01
Since 2025, storms like these have been responsible for a fifth of the
11:06
underwater melting events at Thwaites Glacier.
11:08
And, like regular hurricanes, these processes
11:11
are expected to get worse with increasing ocean temperatures.
11:14
These effects are like the tip of an iceberg when it comes to
11:17
everything that’s been going on with this glacier.
11:19
Simply adding up calving icebergs and underwater melting and rising
11:24
ocean temperatures doesn’t quite equal the glacier loss that we see.
11:28
So measuring how fast Thwaites Glacier is shrinking is complicated.
11:33
And understanding exactly why it’s shrinking is even more complicated.
11:38
To predict what’s going to happen to it in the future,
11:40
and how those changes will affect sea level rise, there’s a lot left we need to understand.
11:45
This all matters because there’s a real chance we could stop the shrinking.
11:49
Scientists have been brainstorming ways to prevent Thwaites Glacier from melting entirely.
11:54
And some of them are pretty surprising.
11:56
Like, researchers have thought of placing reflective material over portions of the glacier,
12:01
or building fences to retain snow that would otherwise blow into the ocean,
12:05
or drying the seabed beneath the glacier so it doesn’t slide toward the ocean as easily.
12:10
But there have also been discussions of building berms or artificial islands
12:15
out of material dredged up from the seafloor or shipped in from elsewhere.
12:19
Placing these structures around or beneath glaciers could protect against
12:23
the warmer ocean water that stirs up vortices and accelerates melting.
12:27
One particularly interesting idea is to build
12:30
flexible sheets that keep cold water close to the glacier and direct warm water away.
12:36
These curtains could keep the glacier frostier, like a coat to keep the cold in.
12:41
But they’d come with a hefty price tag.
12:43
One of those curtains would cost about 50 billion dollars.
12:47
As you can imagine, a lot of these ideas have been controversial.
12:51
And it isn’t just price that has scientists worried.
12:54
Some scientists think that direct interventions
12:56
distract from a much more important goal: lowering global CO2 emissions.
13:01
That’s the number one thing that we can do to stop climate change, and all that it comes with it.
13:06
Including melting glaciers.
13:08
But that said, even if we stopped emitting CO2 tomorrow,
13:11
the ocean wouldn’t stop warming right away.
13:13
So maybe it's a good idea to have some other solutions up our sleeve so we can
13:17
keep Thwaites Glacier from living up to its other, more ominous name.
13:22
[♪ OUTRO]
