From 1989 to 1992, the joint European Greenland Ice-core Project (GRIP) drilled through 3,029 metres (9,935 feet) of ice at Summit station in east-central Greenland before reaching bedrock.
Notes on verification
Multiple independent sources including the official GRIP final report, PANGAEA dataset, and peer-reviewed ESSD paper confirm the 1989-1992 timeframe and 3028.8 m depth at Summit, Greenland. Minor nuance: drilling stopped just short of true bedrock in silty basal ice, but this does not materially contradict the claim.
Sources
- Greenland Ice-core Project/Greenland Ice Sheet Project 2 | geochronology | Britannica (britannica.com)
- https://essd.copernicus.org/articles/15/3351/2023/ (essd.copernicus.org)
- http://pratclif.com/climatechange/grip-final-report.htm (pratclif.com)
- https://doi.pangaea.de/10.1594/PANGAEA.55084 (doi.pangaea.de)
- http://www.nerc-bas.ac.uk/icd/grip/griplist.html (nerc-bas.ac.uk)