Members of the Müller Ice Cap expedition team pose with the final 76 centimeter-long segment of their ice core after drilling to a depth of 613 metres last week on Axel Heiberg Island in Nunavut.Alison Criscitiello/Supplied
An expedition to extract a unique sample from one of Canada’s largest and most venerable ice sheets has hit rock bottom – and that’s a good thing.
Scientists atop the Müller Ice Cap on Axel Heiberg Island in Nunavut report that last Friday their drill struck rock at a depth of 613 metres.
The transition from ice to rock means that the project has achieved its primary goal of drilling out the longest ice core ever obtained in Canada or from any location in the Americas.
The 10-centimetre-wide ice core, which researchers have been pulling up in segments as part of a historic, weeks-long drilling operation, is expected to provide a detailed record of Arctic climate that stretches back to the last Ice Age.
“It is a feeling of great pride and relief to have gotten to this point,” said Alison Criscitiello, director of the Canadian Ice Core Lab at the University of Alberta and a co-leader on the expedition.
Dr. Criscitiello said she and her colleagues knew they were close to the bottom of the ice cap last Thursday when a 76-centimetre-long section of ice core came up looking silty and containing rocks.
That proved to be the final segment. The following day the team attached a pointed metal tip to the drill that they used to see if they could penetrate any further.
“We rammed and drilled into the bottom for a day,” Dr. Criscitiello said. “We did everything we could to confirm bedrock.”
Members of the joint Canadian-Danish expedition began arriving by small plane on the ice cap in early April when temperatures were still hovering around -30 degrees Celsius. After creating a runway for a larger aircraft to bring in equipment and supplies, they set up their camp and drilling work site, including a freezer for storing the ice core segments.
Drilling began on April 16. By April 24, the team had reached a depth of 100 metres and had begun to add fluid to the bore hole to counteract the pressure of the ice at deeper layers.
Time has been a key factor for the expedition because as conditions warm in the 24-hour Arctic daylight, the snow-covered surface of the ice cap is softening and could be unsafe for aircraft as early as mid-June.
The drilling location was selected based on remote sensing data and radar measurements gathered in 2023. While those measurements suggested it might be possible to extract an ice core as long as 600 metres there was no guarantee that the team would not encounter a local rise in the landscape under the ice or some barrier that could prevent them from achieving that depth.
Now that drilling of the main ice core has concluded, Dr. Criscitiello said that the team is working to complete a series of shorter ice cores going down about 70 metres that will provide information on atmospheric contaminants in the High Arctic.
About half of the main core – roughly 3.3 tonnes worth of ice – has already been transported to the laboratory in Edmonton where it will be analyzed in detail, Dr. Criscitiello said, with the rest to follow in the next few weeks.