Scientists retrieve 228-meter rock core from under Antarctic ice, spanning 23 million years

Scientists retrieve longest-ever core from under Antarctic ice

An international research team has extracted a 228-meter core of ancient rock and mud from beneath the West Antarctic Ice Sheet. It is the longest sediment core ever retrieved from below an ice sheet.

Preliminary analysis indicates the core contains a geological record spanning 23 million years. This archive includes periods when Earth's climate was warmer than today and hotter than projections for the year 2100 under current policies.

Drilling for answers on sea level rise

The expedition is part of the Sensitivity of the West Antarctic Ice Sheet to 2 °C (SWAIS2C) project. Its goal is to understand how much this ice sheet retreated during past warm periods and to identify any temperature threshold that triggers irreversible collapse.

The West Antarctic Ice Sheet holds enough ice to raise global sea levels by up to 5 meters. It is already losing mass at an accelerating rate, making understanding its stability a critical climate question.

The team drilled at a remote site called Crary Ice Rise, over 700 kilometers from the nearest station. This location is where the ice sheet is still grounded but nears the point of floating into the Ross Ice Shelf.

A high-stakes Antarctic operation

This season's drilling followed two previous failed attempts due to technical issues. Project co-leader Huw Horgan, a glaciologist at ETH Zurich, described the effort as a "boom or bust" situation.

The process involved first melting a 523-meter hole through the ice with a hot-water drill. The team then deployed a geological rig to core into the bedrock and sediment below.

"Drilling in Antarctic conditions is hard," said Horgan. "You really worry about every single length of core."

What the core could reveal

Initial dating relies on identifying microscopic fossilized algae that lived during specific geologic eras. Scientists will now conduct detailed lab analyses on the core's contents.

The research aims to answer fundamental questions about ice sheet behavior, including:

• How sensitive the West Antarctic Ice Sheet is to specific temperature increases.
• Whether it has collapsed completely in the distant past.
• How quickly it could retreat if current warming trends continue.

The data will help refine models that predict future sea-level rise, providing crucial information for global climate policy and coastal planning.