On board the voyage to Antarctica to learn why a massive glacier is melting

Reporting from Thwaites Glacier, where scientists race weather and time to measure the ice that could reshape the world’s coastlines

[Ed. Note: We just shared our first long broadcast story for PBS News Hour on our adventures in Antarctica. It is embedded below.]

There is a moment on the deck of an icebreaker when the wind cuts through every layer you’re wearing, and the world narrows to three things: ice, water, and the whir of a helicopter fighting to lift itself into a sky that doesn’t always want to cooperate. That’s where we are—moored in the shadow of Thwaites Glacier in West Antarctica, less than twenty miles from the place scientists call the “grounding line”. It is a line in the sand for a warming planet.

Thwaites is often given the cartoonish moniker "Doomsday Glacier”. But standing in front of it, you realize how trite the phrase is. For one thing, it is spectacularly beautiful. This is a glacier roughly the size of Florida, in places more than half a mile thick, sitting on bedrock below sea level and holding back a vast reservoir of inland ice. What happens here won’t stay here. It will show up, eventually, as higher tides on distant coasts and new maps for cities that have existed, comfortably, at the water’s edge for generations.

We arrived aboard South Korea’s research icebreaker Araon, operated by the Korea Polar Research Institute—KOPRI—a ship that feels less like a vessel and more like a moving laboratory. Two helicopters sit in the hangar. The decks are crowded with fuel bladders, radar sleds, hoses, and crates of instruments. There are oceanographers and mathematicians, glaciologists and pilots, engineers and technicians—about forty scientists and and an equal number of crew, all here for a narrow window of work in one of the most unforgiving environments on Earth.

RV Araon in the Amundsen Sea in front of Thwaites Glacier.

Our marquee goal is deceptively simple to describe and brutally hard to carry out: drill a narrow hole through hundreds of meters of ice to the place where ice, land, and sea meet—the grounding line—and lower instruments into the dark water below. Those sensors would give researchers the first long-term, direct measurements of temperature and currents at Thwaites’ most vulnerable point. In a world of models and satellites, this is about getting hands-on with reality.

“This is a special one that over the decades, we’ve discovered is the most crucial to the future of sea level on planet Earth,” David Holland told me, standing in front of a camera as the ship nudged through sea ice. Holland is a mathematician and climate scientist at New York University, and he has spent years turning glaciers and oceans into equations. “Full stop.”

Miles O’Brien and David Holland on the mess deck of the Araon.

Holland has a way of translating abstract science into something you can picture. He describes Thwaites as a kind of keystone—pull it out, and the arch begins to fail. Thwaites doesn’t just contain enough ice to raise global sea levels by a couple of feet on its own. It also appears to help buttress neighboring ice shelves. If it gives way, those could follow, pushing the potential rise closer to ten feet over time.

What makes Thwaites so dangerous isn’t just its size. It’s its shape. Most of us imagine a beach that slopes gently up from the sea. Thwaites is the opposite. Its “beach”—the grounding line—is sloped downward as you move inland. Melt the ice at the front, and thicker ice behind it begins to slide faster, pulled by gravity into deeper water. Holland calls it a runaway.

And it’s not air that seems to be driving the most dramatic melt here. It’s water.

Satellite measurements show parts of Thwaites thinning at rates that dwarf most Antarctic ice—hundreds of feet per year in places, compared to inches elsewhere. Holland’s hypothesis is that changing wind patterns around Antarctica are shifting ocean currents, allowing deeper, warmer water to reach the grounding line. “This is the place where warm water is on your doorstep,” he said. Once that water gets under the ice, the system responds not gradually, but in leaps.

The job of proving—or refining—that theory falls to the team and the gear stacked around me on the deck.

Keith Makinson of the British Antarctic Survey on his way to the hot water drill camp.

Much of it belongs to the British Antarctic Survey, pioneers of hot-water drilling into glaciers. Keith Makinson, an oceanographer and drilling engineer, talks about the operation the way a carpenter might talk about a nail—simple in concept, complicated in execution. They heat water, pump it through a long hose, and melt a hole straight down through the ice. “The complication comes is that we’re in a freezing environment,” he said with a grin. “Nature’s fighting back all the time.”

Then there are the helicopters—and the pilots who decide, minute by minute, whether this expedition moves forward or waits.

Dominic O’Rourke, the chief pilot, spends his mornings studying clouds and contrast, looking for something he calls “reference”—a rock, a ridge, a patch of darker ice, anything that tells the human eye which way is up. Without it, the world becomes a white blur, and spatial disorientation can be deadly. “If we go charging off in there, you’re just in the white,” he warned me over the intercom. “You don’t actually know which way is up anymore.”

This is the rhythm of life here: ambition checked by weather, planning erased by fog, then—if you’re lucky—a sudden opening of blue sky and the thump of rotors as a helicopter lifts off toward the ice.

What makes this particular expedition possible is a choice made far from Antarctica, in government offices and budget rooms in Seoul.

Won-Sang Lee, a principal research scientist at KOPRI, is proud of the ship we’re standing on—and of what comes next. South Korea is building a new research icebreaker, roughly twice the size of Araon, scheduled for delivery around 2030. “We are really grateful for having those kinds of money for continuing our work,” Lee told me. “For better understanding global sea level rise.”

Principal research scientist Won Sang Lee of KOPRI.

Lee explains Korea’s commitment in practical terms. His country is a peninsula, ocean on nearly every side, vulnerable to even millimeters of sea level change. What melts here, he says, matters there. “My country is… facing everywhere the ocean,” he said. “So it’s really vulnerable to what kind of millimeter-wise sea level change.”

There is an irony embedded in that statement. The United States, once the undisputed leader in Antarctic research, is not funding any of the science on this expedition. Budget cuts forced the National Science Foundation to give up its own research icebreaker. Here we are, chasing answers about the future of American coastlines, aboard a Korean ship, supported by Korean taxpayers.

As a journalist, I’m trained to notice those contrasts as much as the ice and the instruments.

Out here, the work feels both audacious and humble. Audacious because we’re trying to reach a place no one has ever measured directly, beneath half a mile of ice, at the edge of a continent. Humble because the glacier doesn’t care about our schedules, our funding cycles, or our sense of urgency. It moves—or doesn’t—on its own terms.

During one of our livestreams, Jamin Greenbaum, a geophysicist from UC San Diego’s Scripps Institution of Oceanography, spoke about what’s at stake beyond the science. “Uncertainty in sea level rise translates to how millions of people will be displaced,” he said. Then, almost in passing, he mentioned leaving home with a newborn just months old to be here. It was a reminder that this expedition is powered not just by diesel and data, but by people willing to trade time with family for measurements that might help strangers decades from now.

Miles O’Brien on the Araon breaking through thick sea ice.