Periodic Reporting for period 1 - MICRO-CLIMATE (Micron-scale Ice Core Reconstruction of Abrupt Climate Changes)
Okres sprawozdawczy: 2022-01-15 do 2024-01-14
Polar ice cores are an indispensable key to understanding the natural dynamics of our climate system. One of today’s most pressing research questions concerns the prediction and mechanics of abrupt climate change (ACC). This has particular significance for the Arctic, one of the fastest warming regions on the planet. Ice cores drilled on polar ice sheets have informed us of past abrupt climate transitions, such as the abrupt onset of “Dansgaard-Oeschger events” (DO) in Greenland. Happening over just a few years to decades, the study of the events can serve as past analogues to present and future ACC. Polar ice cores archive proxies for past changes in atmospheric transport of soluble and insoluble chemistry. However, fine temporal detail is required to decipher the fundamental processes and precursors of ACC. Due to continuous thinning of layers with depth, conventional cm-resolution melting techniques may not always provide adequate detail, motivating the use of novel high- resolution analysis. At micron scale resolution, however, it is pivotal to avoid misinterpretation by taking into account post-depositional layer disturbances, especially the interaction of impurities with the ice crystal matrix. This can be achieved by carefully mapping the spatial impurity distribution in 2D. The technique of Laser-Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) is unique in offering micron scale-resolution ice core impurity analysis AND imaging the spatial impurity distribution. The combination of the two strengths has not yet been exploited, however. The MSCA Global Fellowship MICRO-CLIMATE has used a unique opportunity to take a leap forward in LA-ICP-MS ice core analysis of ACC, by having two leading groups join forces: Among few existing LA-ICP-MS setups used for ice core analysis, the Climate Change Institute (CCI) at the University of Maine, USA has pioneered a system with a large cryogenic chamber. Recently, LA-ICP-MS at Ca’Foscari University of Venice (UNIVE) has been optimized with state-of-the-art 2D imaging techniques to investigate the impurity distribution in small ice core samples at high resolution, thus providing the tool to avoid misinterpretation at the micro-scale. During the course of the project, the fellow was awarded with the ERC Consolidator grant “AiCE”, which impacted also the course of the MSCA-GF fellowship: it was decided to conclude MICRO- CLIMATE at the end of 2023, in order to enable starting the ERC project in 2024. In spite of having been compressed into two instead of three years, the majority of the research, training and dissemination objectives has been completed or partially reached. The main limitation to the scientific objectives regards the amount of ACC events studied, while at the same time, an individual event has been studied in even more detail than originally anticipated. This sets a method that can be further exploited in follow-up projects. In conclusion, MICRO-CLIMATE has led to significant scientific insight, technological developments and strengthening of institutional partnerships. The strong career boost to the fellow can only be regarded as highly positive but had a strong impact on the project by leading to finishing one year earlier than anticipated.
Following the start phase and the secondment period at the Alfred-Wegener-Institute Helmholtz Center for Polar and Marine Research (AWI), a comparison between 2D LA-ICP-MS images and Cryo-Raman spectroscopy on Greenland ice core samples demonstrated that dust-related chemical elements such as Al, Si and Fe can be highly localized in clusters of dust particles. Samples of a Greenland ice core were selected and shipped to CCI for further analysis. In order to compare data collected by both LA-ICP-MS systems, we included ice samples that were already analysed in Venice. This included the first inter-lab comparison on LA-ICP-MS ice core analysis. A total of 4 bags of 55 cm length were analysed at CCI, and parts of 2 of these bags in Venice. So far, the project has resulted in five peer-reviewed articles and nine conference presentations. Data evaluation and preparation of the final manuscript is still ongoing.
Based on the experience collected with two LA-ICP-MS setups for 2D imaging and 1D depth profiling, the goal was to conceptualize a revised approach that offers both applications in a single setup: A large cryo-cell with 2D imaging capabilities and high scan speed. This technological innovation should pave the way for further extended use of LA-ICP-MS ice core analysis in 1D and 2D.
Based on the experience collected with two LA-ICP-MS setups for 2D imaging and 1D depth profiling, the goal was to conceptualize a revised approach that offers both applications in a single setup: A large cryo-cell with 2D imaging capabilities and high scan speed. This technological innovation should pave the way for further extended use of LA-ICP-MS ice core analysis in 1D and 2D.
MICRO-CLIMATE has successfully brought together two research groups leading ice core analysis using Laser-Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS). Through the exchange of know-how and the joint development of hardware all involved institutions have benefitted from this project. This project led to a new combination of two different experimental approaches; 1D line profiling to retrieve stratigraphic paleoclimatic signals and 2D imaging to investigate signal preservation and ice-impurity interactions. This new approach can be further refined and adapted for the benefit of other ice core projects, such as the ongoing “Beyond EPICA: Oldest Ice Core”. The results of MICRO-CLIMATE will contribute to a better understanding of abrupt climate change and provide additional context to the ongoing warming we see in the Arctic today.