What does a chunk of ice sound like when it hits the bottom of a 90-meter hole in a glacier?

The answer: Something like a bullet whizzing by your head.

For University of Minnesota Prof. Peter Neff, a viral tweet showing this phenomenon launched his scientific work into the world of social media, where he's now educating TikTok users about polar ice and climate change.

Neff, 35, is a glaciologist and climate scientist who has made multiple trips to Antarctica to sample ice that's hundreds of thousands of years old. He landed on TikTok in the midst of a push by the company two years ago to lure experts to the video-sharing app.

For every post, a flood of comments pour in: What do we know about Earth's climate from thousands of years ago? What tests are run on the ice that scientists drill?

And: What's the oldest piece of ice Neff has ever put in a glass of whiskey? (About 100,000 years old; it wasn't usable for testing.)

The platform provides regular people rare access to a climate scientist, Neff said.

"It has an impact on people who see the stuff and get their interest piqued in trying to become a polar scientist too," he said.

While discussing climate change can invite nasty responses, Neff's commenters usually want to know more about the science.

Using social media is one of a few ways his career has changed. Neff used to joke that his research was a sure way to get annual field trips. Now, he is much more motivated by understanding the forces behind a warming Earth, he said.

Antarctic science is in a catch-up moment, after two years of COVID-related disruptions to field work. Paul Cutler, the program director for Antarctic science at the National Science Foundation, said any new projects far from the U.S. base of operations are now three years behind.

At the same time, a research race is underway. Scientists in the United States and several other parts of the world are searching for some of the oldest ice on the planet. And Neff will be a part of it.

"They're really trying to address fundamental questions about how the climate system works," Cutler said.

Drilling down

Researchers have been drilling ice cores for decades to puzzle out long-term trends in the planet's past climate. The longest continuous record stretches back 800,000 years.

This research provides perspective on how human-caused warming may affect some of the continent, like Thwaites Glacier. The melting glacier holds back a massive floe of ice that could raise sea levels significantly.

But the most important part of these records isn't the ice itself. Instead, researchers analyze the air bubbles caught between crystals of frozen water. The air is sandwiched between falling snowflakes on Antarctica, and over time, layer by layer, compressed into the ice sheet.

"That air space just gets locked in, which is a direct sample of the atmosphere," Neff said. Scientists can test for greenhouse gases like methane and carbon dioxide, providing data that show how the planet has swung between ice ages and hotter periods in the past.

It was a historical perspective, in fact, that first drew Neff to geology and then polar work as an undergrad at the University of Washington. These days he's married to fellow U professor Heidi Roop, and living in St. Paul.

"You can go on a hike. And not only do you get this three-dimensional experience, you're gonna have a fourth dimension of time," Neff said. "I understand why this valley is U-shaped. It's because there was a glacier in it ... That's where it starts."

Antarctica is perhaps the best place on the planet for this work. The ice almost never melts, and it's clean. On the Greenland ice sheet on the opposite end of the of the globe, far more dust blows into the ice, corrupting the air samples.

Neff's published work focuses on the "brittle ice zone," an area between 500 and 1,500 meters deep where the ice is under pressure and can break when brought to the surface. He's also contributed to papers from the West Antarctic Ice Sheet (WAIS) Divide ice core, the second-deepest ever drilled.

In the field

With isolation on Antarctica comes tough working conditions. Neff compared the isolation and camaraderie in field camps to combat situations, though it's the elements they're fighting.

John Goodge, an emeritus professor from the University of Minnesota in Duluth, described some of the challenges: Machinery runs all the time so it doesn't freeze. Energy needs are high to melt the ice and snow into drinking water. It's possible to get altitude sickness on the miles-high peaks of the ice sheet.

And usually, the cold is intense.

"Every time I've been there, you step off the airplane flying down from New Zealand, and you're just never quite prepared for it," said Goodge, who studies the mountains and valleys buried under the ice.

Even in these frigid conditions, ice cores are kept extremely cold. As a graduate student, Neff helped to measure and cut pieces of ice on the WAIS Divide project. He worked in the refrigerated storage room, at negative 30 degrees Fahrenheit.

The researchers and staff find ways to work through the cold together — like dancing in the storage room, as Neff has shown on his TikTok.

"It's like you form a little family each time you're in a field camp," he said.

Then, they scatter around the globe when the work is done.

Going deeper

With COVID restrictions easing in New Zealand, the transit point for U.S. researchers bound for Antarctica, more work is re-starting. One ambitious initiative is the Center for Oldest Ice Exploration, abbreviated as COLDEX.

The aim of COLDEX is to find a location to drill an ice core that goes back 1.5 million years. This span reaches back to a period when the earth switched between ice ages and warm periods more than twice as fast as it does now. It's unclear why the cycles have lengthened.

"This is a fundamental question: How does the engine of the earth system work?" Neff said.

Some drilling will happen in a region where the ice sheet has scraped against mountains, pushing older ice closer to the surface.

Pilots will fly radar-equipped planes around the South Pole to search for locations that might be suitable for a deeper core.

And Goodge hopes his work will also be a part of the project — he has developed a tool called the Rapid Access Ice Drill, which can quickly bore down to search for good locations to drill a deeper core.

Neff serves as director of field research and data for COLDEX. He'll be at the U.S. center of operations, McMurdo Station, coordinating between teams in the field and the main hub.

And, he said, he'll be sharing progress on the projects on his TikTok, for all to see.

Neff got the post, he said, because he's been able to work well with any team he's been placed in. For those interested in similar work at the poles, Neff said that adaptability is the most important part of the job.

"It's mostly going to be some combination [of] focus, determination and enthusiasm," Neff said. "That's really what it takes."