CH 4 and N 2 O fluctuations during the penultimate deglaciation

• Published in: Climate of the Past
• Main Authors: L. Schmidely, C. Nehrbass-Ahles, J. Schmitt, J. Han, L. Silva, J. Shin, F. Joos, J. Chappellaz, H. Fischer, T. F. Stocker
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Dansgaard-Oeschger events; EPICA; ice core
• Online Access: https://doi.org/10.5194/cp-17-1627-2021; https://doaj.org/article/43488640a03b4e1abf5806869b54a039

Deglaciations are characterized by the largest natural changes in methane (CH 4 ) and nitrous oxide (N 2 O) concentrations of the past 800 000 years. Reconstructions of millennial- to centennial-scale variability within these periods are mostly restricted to the last deglaciation. In this study, we present composite records of CH 4 and N 2 O concentrations from the EPICA Dome C ice core covering the penultimate deglaciation at temporal resolutions of ∼100 years. Our data permit the identification of centennial-scale fluctuations during the transition from glacial to interglacial levels. At ∼134 000 and ∼129 000 years before present (hereafter ka), both CH 4 and N 2 O increased on centennial timescales. These abrupt rises are similar to the fluctuations associated with the Dansgaard–Oeschger events identified in the last glacial period. In addition, gradually rising N 2 O levels at ∼130 ka resemble a pattern of increasing N 2 O concentrations on millennial timescales characterizing the later part of Heinrich stadials. Overall, the events in CH 4 and N 2 O during the penultimate deglaciation exhibit modes of variability that are also found during the last deglaciation and glacial cycle, suggesting that the processes leading to changes in emission during the transitions were similar but their timing differed.