Ice Core Methane Analytical Techniques, Chronology and Concentration History Changes: A Review

Ice cores are invaluable in paleoclimate research, offering unique insights into the evolution of the natural environment, human activities, and Earth’s climate system. Methane (CH 4 ) is a crucial greenhouse gas, second only to CO 2 in its contribution to global warming, and is one of the primary anthropogenic greenhouse gases. Understanding historical CH 4 concentration changes is essential for predicting future trends and informing climate change mitigation strategies. By analyzing gas components trapped in ice core bubbles, we can directly examine the composition of ancient atmospheres. However, there are relatively few comprehensive reviews on ice core CH 4 testing techniques, chronology, and concentration history records. In response to this gap, our paper systematically reviews ice core CH 4 analytical techniques, chronology, and concentration history changes. Our review indicates that current research on CH 4 in non-polar ice cores is insufficient compared to polar ice cores, facing challenges such as high data dispersion, outlier frequency, and the presence of non-atmospheric signals. These limitations hinder our in-depth understanding of CH 4 signals in non-polar ice cores, and the reliability of atmospheric CH 4 concentration changes they reflect. To address these challenges, we propose exploring and applying advanced testing techniques, such as Continuous Flow Analysis technology, in non-polar ice cores. Additionally, we emphasize the research gap in utilizing CH 4 records for age determination in ice core chronology. Future research should focus on this area to advance our understanding of ice core chronology and the history of atmospheric CH 4 changes in non-polar regions, ultimately contributing to more effective climate change mitigation efforts.