Abrupt climate change and Greenland ice cover in a high-resolution ice core record

Understanding how Earth’s climate naturally behaves is crucial for dealing with abrupt climate change, especially in the rapidly warming Arctic. The study of polar ice cores is fundamental for investigating these sudden shifts because they preserve detailed layers of past snowfall. These layers contain chemical “clues” that reveal important information, such as sea-ice conditions and wind-blown dust, allowing scientists to reconstruct past climate changes.

Ice cores from Greenland are particularly valuable because they provide high-precision timelines stretching back thousands of years and capture rapid climate transitions, such as the Dansgaard–Oeschger events, which occurred within decades. The Renland ice cap in East Greenland lies close to the coast, making it especially sensitive to changes at the margin of the Greenland Ice Sheet and a valuable complement to central Greenland ice cores. The RECAP ice core, drilled 584 m down to bedrock, preserves a complete climate record spanning 120,000 years.

A remarkable feature of tRECAP is that the entire glacial period (about 10,700–115,000 years ago) is compressed into just 20 m of ice, meaning that 1 cm of core represents roughly 100 years. This extreme thinning makes RECAP an ideal site for applying cutting-edge, high-resolution analytical techniques.

The “Abrupt climate change and Greenland ice cover in a high-resolution ice core record” project aims to investigate how and why the Arctic climate underwent abrupt changes in the past. To achieve this, researchers studied the impurities trapped in the RECAP ice core, drilled from the Renland ice cap in eastern Greenland. The chemical and physical signatures of these tiny particles act as “clues” that reveal what past atmospheric conditions were like: they show how air circulated, how dry the continents were, how much snow fell, and how extensive sea ice was.

Although the project focuses primarily on the RECAP core, additional ice cores and related materials have also been analysed. The initial plan involved using advanced techniques at Ca’ Foscari University of Venice, such as 2D laser ablation ICP-MS imaging, followed by complementary analyses of the same samples using a Coulter Counter and low-background instrumental neutron activation analysis at the University of Milano-Bicocca. Thanks to PRA funding, however, the project expanded and established collaborations with two major European research institutions: the Alfred Wegener Institute in Germany and the University of Graz in Austria. There, researchers were able to work with state-of-the-art instruments, enabling even more detailed investigations, such as single-particle analysis with ICP-ToF-MS and 1 kHz LA-ToF-MS systems for 2D impurity imaging.

The project has led to several advances that significantly improve how we analyse and interpret polar ice cores. One major achievement is the development of a new high-resolution method for measuring soluble impurities in ice using LA-ICP-MS and artificial ice standards. This approach greatly enhances our ability to detect fine-scale chemical signals and enables direct comparison with traditional continuous-flow analysis. Such capability will be vital for studying extremely old and delicate ice, including million-year-old Antarctic cores.

The project has also deepened our understanding of how physical properties vary within deep ice, offering new insights into the preservation of climate signals. Work with single-particle ICP-ToF-MS has demonstrated that even very small, previously analysed ice samples can provide detailed information on insoluble particles, expanding our capacity to reconstruct past atmospheric conditions.

Bohleber, P., Larkman, P., Stoll, N., Clases, D., Gonzalez de Vega, R., ala, M., Roman, M., and Barbante, C.: Quantitative insights on impurities in ice cores at the micro scale from calibrated LA ICP MS imaging. Geochemistry, Geophysics, Geosystems, 25, e2023GC011425. https://doi.org/10.1029/2023GC011425, 2024.
https://doi.org/10.1029/2023GC011425 

Larkman, P., Vascon, S., ala, M., Stoll, N., Barbante, C., and Bohleber, P.: Faster chemical mapping assisted by computer vision: insights from glass and ice core samples, Analyst, 150, 3408, 10.1039/D5AN00325C, 2025b.
10.1039/D5AN00325C

Larkman, P., Rhodes, R. H., Stoll, N., Barbante, C., and Bohleber, P.: What does the impurity variability at the microscale represent in ice cores? Insights from a conceptual approach, The Cryosphere, 19, 1373–1390, https://doi.org/10.5194/tc-19-1373-2025, 2025a. https://doi.org/10.5194/tc-19-1373-2025 

Stoll, N., Weikusat, I., Jansen, D., Bons, P., Darányi, K., Westhoff, J., Llorens, M.-G., Wallis, D., Eichler, J., Saruya, T., Homma, T., Rasmussen, S. O., Sinnl, G., Svensson, A., Drury, M., Wilhelms, F., Kipfstuhl, S., Dahl-Jensen, D., and Kerch, J.: Linking crystallographic orientation and ice stream dynamics: evidence from the EastGRIP ice core, The Cryosphere, 19, 3805–3830, https://doi.org/10.5194/tc-19-3805-2025, 2025b. https://doi.org/10.5194/tc-19-3805-2025

Stoll, N. A., Clases, D., Gonzalez de Vega, R., Elinkmann, M., Larkman, P. M., and Bohleber, P.: New insights on particle characteristics of previously characterised EGRIP ice core samples via single particle ICP-TOFMS, EGUsphere [preprint, in revision], https://doi.org/10.5194/egusphere-2025-61, 2025a. https://doi.org/10.5194/egusphere-2025-61 

Bohleber, P., Stoll, N., Larkman, P., Rhodes, R. H., and Clases, D.: New evidence on the microstructural localization of sulfur, chlorine & sodium in polar ice cores with implications for impurity diffusion, EGUsphere [preprint, accepted], https://doi.org/10.5194/egusphere-2025-355, 2025. https://doi.org/10.5194/egusphere-2025-355 

Masiol, M., Stoll, N., Larkman, P., Clases, D., Gonzalez de Vega, R., Di Stefano, E., Delmonte, B., Barbante, C., and Bohleber, P.: New insights on dust particles in Greenland ice cores combining state-of-the-art methods, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7265, https://doi.org/10.5194/egusphere-egu25-7265, 2025. https://doi.org/10.5194/egusphere-egu25-7265

Stoll, N. Chemical impurities in the microstructure of polar ice and the potential of embedding analytical chemistry. Invited talk at “Young Analysts Forum of the Austrian Society for Analytical Chemistry” (Austria, 16.05.2024), 2024

Stoll, N., Larkman, P., Clases, D., Gonzalez de Vega, R., Di Stefano, E., Delmonte, B., Barbante, C., and Bohleber, P.: Characterising dust particles in the RECAP ice core with a multi-method approach to investigate abrupt climate changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9596, https://doi.org/10.5194/egusphere-egu24-9596, 2024.

Bohleber, P., Stoll, N., Larkman, P., Korotkikh, E., Gadrani, L., Kurbatov, A., Mayewski, P., Barbante, C., and Delmonte, B.: Laser Ablation impurity images and profiles in Holocene and Glacial ice of the Renland ice cap. AGU 2023 (USA, 11-15.12.2023), 2023. https://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1345201

Bohleber P., Stoll N., Larkman P., Masiol M., Barbante C., and Delmonte B.: Abrupt climate change and Greenand ice core highresolution ice core record. Ricerche in Artico – Le sfide della ricerca (Italy, February 9.02. 2023), 2023
https://www.cnr.it/it/eventi/allegato/13214