On the edge of the West Antarctic Ice Sheet, a group of scientists spent weeks living in tents on wind-blown snow, taking turns day and night.

They weren’t looking for wild animals or claiming territory. They were drilling deep beneath the ice to recover ancient mud.

Beneath more than 400 meters of ice, that mud can tell stories that the ice alone can’t tell.

The mud preserves clues from past warm periods, revealing how the ocean changed and the Antarctic ice sheet responded when the climate was hotter and more unstable than it appears today.

Why drill beneath the ice sheet?

ice sheet Don’t just sit there. They crawl, crack, and sometimes retreat quickly.

The West Antarctic Ice Sheet is a major concern because it holds enough ice to lift it up. world sea level If fully melted, it will advance approximately 13 to 16 feet.

Satellites in recent decades have shown that mass loss is accelerating, but scientists still don’t know the exact amount of warming that could lead to rapid mass loss.

For years, researchers have had to piece together the ice sheet’s past using clues collected nearby, next to the ice, beneath floating ice shelves, or in sediments drilled in the open Ross Sea or Southern Ocean.

While these sedimentary records are valuable, they cannot match the insight gained by drilling just beneath the ice sheet itself.

That’s what makes this new drilling operation so unusual. An international team drilled a 748-foot-long sediment core of ancient mud and rock from beneath 1,716 feet of ice.

Key insights into future global warming

The work took place at deep camp at Crairie Ice Rise, more than 735 miles from the nearest Antarctic bases, Scott Station in New Zealand and McMurdo Station in the United States.

The name of the project is SWAIS2C – West Antarctic Ice Sheet sensitivity is 2°C. The project was led by co-principal scientists Dr Hugh Horgan and Dr Molly Patterson.

“This record will provide important insight into how the West Antarctic Ice Sheet and Ross Ice Shelf respond to temperatures above 2°C,” said Dr Hogan, a geophysical glaciologist. Victoria University of Wellington.

“The first indication is that the core’s sediment layers span the past 23 million years, including a period when Earth’s global average rose. temperature It was significantly more than 2 degrees Celsius higher than before the industrial revolution. ”

If this initial estimate is correct, this core covers more than just several ice ages. It goes back a long time. carbon dioxide levelthe heat of the ocean, and the coastline looked much different than it does today.

This is important because climate scientists use the past as a reality check. Computer models can simulate ice loss, but real evidence from actual warm periods can help test whether those models actually behave the same way as on Earth.

Variation between deposits

When the researchers pulled up the core in sections about 10 feet long, they noticed that the sediments were not all the same. Some layers looked similar to those beneath the ice sheet. others were not.

“We saw a lot of variation. Some of the deposits were typical of deposits that occur under ice sheets, such as today’s Crary Ice Rise,” Dr. Patterson said.

“But we also saw more typical material. open oceanan ice shelf floating above the ocean, or the edge of an ice shelf iceberg I’m in labor. ”

Some of the strongest hints of the open ocean have come from shell fragments and the remains of marine life that needs light to survive.

Light cannot reach through hundreds of feet of ice, suggesting that at some point in the past the site was not buried under ice as it is today.

Scientists already believe that parts of this area may have once been open ocean, meaning that the Ross Ice Shelf has retreated, and that the West Antarctic Ice Sheet may have also retreated significantly.

Environmental conditions over time

The problem was timing. During what warm period did it happen? How warm was the Earth when it happened? And what were the oceans doing?

“This new record provides a set of environmental conditions over time and points to the truth of the existence of an open ocean in this region,” Dr Patterson said.

“In addition to determining the time when this happened and the corresponding global temperature, the analysis will help quantify the environmental factors that caused the ice sheet retreat, including determining the ocean temperature at the time.”

Ocean temperature is important because warm water can erode ice from below. Even if the air is frozen, even a little warm sea As the ice shelf becomes thinner, its grip becomes weaker and the glaciers behind it can move faster.

Science at the edge of the map

This was no simple drilling job, as there were warm buildings nearby and spare parts on shelves. The team included 29 scientists, drillers, engineers and polar experts camping on the ice.

“To our knowledge, the longest sediment core ever drilled beneath an ice sheet is less than 10 meters long. We exceeded our target of 200 meters and conducted this 700 kilometers from the nearest base. This is Antarctic frontier science,” Dr. Patterson said.

Just reaching the deposits required drilling 1,716 feet of ice and melting boiling water. They then lowered more than 4,265 feet of pipe into the hole.

As each section of the core reached the surface, the pace shifted to focused precision.

Scientists recorded its characteristics, photographed the layers, X-rayed the tubes, and collected samples. We then sent the drill back for the next segment, racing against the clock where every minute counts on the field.

“You feel great when the first core shows up, but then you start worrying about the next core, and the one after that. So it’s stressful all the way through,” Dr. Hogan said.

“However, we have learned from previous challenges and are excited to have successfully recovered this geological record that will help the world prepare for the impacts of climate change.”

The future of Antarctic glacier reserves

Preliminary dating at the site relied on small fossils of marine life found in several layers. This is a classic method of estimating age because specific microfossils appear in a known time frame.

Then comes slower, more precise work. Our extensive team in 10 participating countries uses multiple methods to review and adjust schedules.

The core will be returned to Scott Station and immediately headed to New Zealand, where samples will be distributed to scientists around the world for further analysis.

“Our international multidisciplinary team is already working together to uncover the core climate secrets,” Dr Hogan said.

“Our drilling system has been tested under these harsh Antarctic conditions with great success. We look forward to planning future drilling to continue our mission to learn more about the sensitivity of the West Antarctic Ice Sheet to global warming.”

Big goals are easy to say but difficult to answer. That is how quickly Antarctic ice will retreat as the Earth’s temperature rises.

This muddy archive, pulled from beneath a place most humans never see, may ultimately shape how the rest of us plan for sea level rise in the coming decades.

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