Sea level rise will be one of the greatest
challenges we face in the next century.
How high seas rise and how soon has a lot to do with what happens here.
Antarctica holds the largest chunk of ice
on Earth.
Its western portion alone contains enough
ice to raise sea levels by more than 3 meters.
And it’s in big trouble. Largely because
of this,
the Thwaites glacier.
Its face towers as high as a six-story building,
and extends for 120 kilometers across the coast of West Antarctica. Making it about
the size of Florida.
It’s a humongous glacier that reaches right
into the heart of West Antarctica.
And that’s a major problem, because in
the past couple decades, it’s become increasingly clear
The Thwaites glacier is falling apart.
These are portraits of a vast, rugged, treacherous continent.
Which has challenged man since first he could sail beyond the limits of his horizon.
Antarctica.
This is the Antarctic ice sheet.
It's thickest in the middle, where years and
years of snowfall compacts into ice.
As the middle builds, it pushes ice out towards
the oceans via glaciers.
And the part of a glacier that floats on water
is its “ice shelf.”
Today, man-made climate change is warming
the air and water around Antarctica, causing
each side of the ice sheet to melt - but at
very different speeds.
The Eastern ice sheet lies mostly on high
ground, above sea level, which keeps it relatively
safe from warm ocean water.
That means it’s melting slowly and remains
relatively stable.
But West Antarctica is different; most of
it lies below sea level.
That means as it thins, water can undermine
it. Possibly kick-starting a more rapid collapse.
It’s why West Antarctica is considered the
most important piece of ice in the world when
it comes to climate change.
Here’s another view of the bedrock underneath
Antarctica’s ice sheet.
The green, yellow, and red parts are land
above sea level. Like in East Antarctica.
But these blue areas in West Antarctica are all below sea level.
This area, where the bedrock slopes continuously
for more than a mile down and deep into the
center of Antarctica, is the Thwaites Glacier.
And it could be the most dangerous glacier
in the world.
Surrounded by three mighty oceans,
the seas are as much apart of Antarctica, as her highest mountain.
Right now, Thwaites is barely hanging on.
In the past 30 years, the front of Thwaites’
ice shelf has lost a lot of ice, causing it
to retreat backwards. With a smaller ice shelf
to slow the flow of ice, the flow of the glacier
speeds up.
But the bigger problem is the glacier’s
"grounding line", the final point where the
glacier rests on the bedrock.
That grounding line has been shifting backwards
as warm ocean water reaches underneath the
ice shelf. It’s moved 14 kilometers since
1992.
So ice that used to be on land becomes ice
that is floating on water, raising sea levels.
The downhill slope of the bedrock means that
as the grounding line moves back, it lifts
an even bigger slice of ice behind it off
the land and into the water. And that accelerates
the flow of the glacier into the sea.
The amount of ice flowing from Thwaites has
doubled over the past 30 years.
And already contributes 4% to global sea level
rise.
And scientists have recently detected a huge
cavity two-thirds the size of Manhattan down here.
Scientists believe this could mean Thwaites’
collapse is inevitable.
How soon that happens is hotly debated.
The sleeping continent is awakening. Slowly at first.
But with ever-gathering momentum.
The complete collapse of Thwaites will take
centuries and its affected by many different
things; from the temperature of the ocean
currents to the makeup of the bedrock.
But the research shows that humans can possibly
slow or even stall its collapse by curbing
greenhouse gas emissions soon.
That’s important because some scientists
believe collapse could start this century,
while others say it’s already underway.
The collapse of Thwaites would add about half
a meter of sea level rise.
And trigger a much bigger catastrophe.
Because Thwaites reaches into the middle of
West Antarctica, its collapse could cause
the rest of the ice sheet to collapse with
it,
resulting in more than 3 meters of sea level
rise in the next few centuries.
That would submerge not only Miami and southern
Bangladesh but also parts of the Netherlands
and New York City.
So while there’s still a lot of uncertainty
around Thwaites, one thing is clear,
once it starts to collapse… it won’t stop.
