Environmental researchers can dig deeper into glacial cores with a new laser melting sampler (LMS) devised by Japanese scientists. With a 3-mm depth-resolution, the instrument can detect temperature variations that occurred over much shorter timer periods.

Available ice core sampling methods are limited by an inability to perform at this finer scale or by poor preservation of the sample needed to analyze the water content. By contrast, the new tool is expected to enable analysis of stable water isotopes at a few-millimeters depth resolution and obtain continuous, long-term, annually resolved temperature profiles, even in deep ice cores collected at low accumulation sites in polar regions. The approach also protects the critical oxygen and hydrogen isotopes found in water, which are needed to infer past temperature. The resulting data will improve climate change studies through the reconstruction of continuous annual temperature changes that occurred thousands to hundreds of thousands of years ago.

Schematic development diagram detailing the components of the sampling unit. Source: Journal of Glaciology, doi.org/10.1017/jog.2023.52

The LMS system delivers a laser beam through an optical fiber with a special silver nozzle, and quickly pumps out the liquid sample, eventually depositing it into stainless steel vials. Researchers from RIKEN Nishina Center, RIKEN Center for Advanced Photonics and the National Institute of Polar Research tested the method by collecting 15 cm segment ice samples at about 92 m below the ice surface in Antarctica. The stable oxygen and hydrogen isotopic contents in the meltwater extracted from the samples matched well with those determined in samples taken by hand segmentation, a process only practical in this research setting.

The research published in the Journal of Glaciology confirms that the LMS protected the sample and that the inferred temperatures would be accurate.