Multiple sources of atmospheric CO2 activated by AMOC recovery at the onset of interglacial MIS 9

• 成果类型: Article
• 署名作者: Krauss, Florian; Baggenstos, Daniel; Schmitt, Jochen; Tuzson, Bela; Menking, James A.; Machler, Lars; Silva, Lucas; Grimmer, Markus; Capron, Emilie; Stocker, Thomas F.; Bauska, Thomas K.; Fischer, Hubertus
• 署名单位: University of Bern; University of Bern; Australian Antarctic Division; University of Tasmania; Swiss Federal Institutes of Technology Domain; Swiss Federal Laboratories for Materials Science & Technology (EMPA); Commonwealth Scientific & Industrial Research Organisation (CSIRO); INRAE; Communaute Universite Grenoble Alpes; Universite Grenoble Alpes (UGA); Institut de Recherche pour le Developpement (IRD); UK Research & Innovation (UKRI); Natural Environment Research Council (NERC); NERC British Antarctic Survey
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-15261
• DOI: 10.1073/pnas.2423057122
• 发表日期: 2025-06-10
• 关键词: epica dome-c; meridional overturning circulation; greenhouse-gas analysis; abrupt climate-change; carbon-dioxide; southern-ocean; ice core; last; variability; record

摘要

Using high-precision ice core measurements of CO2, S13C-CO2, CH4, and N2O, this study provides carbon isotope constraints on a sizeable, centennial-scale CO2 jump at the onset of Marine Isotope Stage 9 (MIS 9). The very end of the Heinrich stadial (HS) characterizing Termination IV (T-IV, ca. 343 to 333 ka ago) shows a 250-y-long jump in greenhouse gas concentrations, followed by a 1.3 ka gradual decline back to the initial concentration. During this so-called overshoot, CO2 and CH4 reach their highest levels (about 303 ppm and 800 ppb, respectively) over the past 800 ka prior to industrialization. The jump in CO2 is not accompanied by a change in S13C-CO2, suggesting that multiple mechanisms contributed to the exceptionally elevated CO2 values. Following the jump, a slow 0.2 parts per thousand enrichment in S13C-CO2 occurs. We propose that during the jump, the sudden resumption of deepwater formation in the North Atlantic (NA) triggered an amplified release of CO2 from the Southern Ocean (SO) by a northward shift of the Intertropical Convergence Zone (ITCZ) and the SO westerlies, potentially in combination with a rapid land carbon release. The latter is expected from temporally enhanced wildfire activity related to higher fuel load and regionally changing weather conditions in connection to the ITCZ shift. A combination of marine proxy records and box model simulation suggests that the S13C-CO2 decrease expected from these processes is compensated by a net temperature increase in global sea surface temperature (SST) at the time of the AMOC resumption.