Antarctic research is advancing thanks to a new krypton-81 ice-dating technique that deepens our understanding of how the paleoclimate changed over millions of years.
In a unique blend of quantum physics and glaciology, Professors Zheng-Tian Lu and Wei Jiang from the University of Science and Technology of China (USTC) led the development of the new All-Optical Atom Trap Trace Analysis technique. Working in collaboration with American glaciologists, they successfully tested this innovative approach on ancient Antarctic ice samples.
The Antarctic Ice Dating Challenge
The thick ice layers in Antarctica and on the Greenland ice sheet offer a valuable but difficult-to-interpret record of climate history and ice sheet evolution, similar to tree rings, but stretching far deeper into Earth’s past. While tree rings measure material in feet, ice core samples reach depths measured in kilometers. These layers reveal significant climatic shifts, yet precise dating remains difficult due to stratigraphic disturbances.
A potential solution to this challenge lies in the rare radioactive isotope krypton-81. If harnessed effectively, krypton-81 could simplify the dating of ice samples. However, its rarity presents a significant obstacle: a single kilogram of ice contains only a few hundred atoms of the isotope, creating a needle-in-a-haystack scenario for researchers.
Overcoming Krypton-81’s Elusiveness
Lu and Jiang’s team at USTC first developed an all-optical single-atom detection technique in 2021. Over the next four years, they refined their method into a highly advanced process capable of accurately dating real-world samples. Central to this breakthrough was creating a high-brightness, narrow-bandwidth vacuum-ultraviolet light source that enabled nondestructive measurement.
This light source allowed the team to generate metastable krypton atoms while reducing cross-contamination by two orders of magnitude. They also enhanced the method’s efficiency by lowering the krypton gas sample requirement to just 100 nanoliters—equivalent to the amount in 1 kg of ice—and extended the dating range to 1.5 million years.
Cross-Disciplinary Collaboration
With their process in place, Lu and Jiang initiated an international collaboration to validate their findings. They partnered with Princeton University glaciologists Professor Michael Bender and Dr. Sarah Shackleton, analyzing 1 kg ice samples collected from Antarctica’s Taylor Glacier—a 35-mile-long glacier grounded on bedrock rather than floating on water.
The team confirmed the accuracy and reliability of the new method by comparing the krypton-81 dating result of approximately 130,000 years with precise age estimates derived from stratigraphic alignment. This development provides scientists with a powerful new tool for studying small ice core samples to uncover Earth’s climate history.
Continuing to Probe the Frozen Past
Lu and Jiang do not consider their work complete. Their team at USTC is currently collaborating with glaciologists both within China and internationally to apply the technique to basal ice samples from Greenland, Antarctica, and the Tibetan Plateau.
Their efforts aim to improve understanding of Tibetan glacier timelines, assess the stability of the Greenland ice sheet, and identify ancient ice dating back to the Mid-Pleistocene Transition, offering valuable insights for paleoclimate science and glaciology.
The paper “81Kr Dating of 1 kg Antarctic Ice” appeared on May 19, 2025, in Nature Communications.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.