Southern Ocean drives multidecadal atmospheric CO2 rise during Heinrich Stadials

• 成果类型: Article
• 署名作者: Wendt, Kathleen A.; Nehrbass-Ahles, Christoph; Niezgoda, Kyle; Noone, David; Kalk, Michael; Menviel, Laurie; Gottschalk, Julia; Rae, James W. B.; Schmitt, Jochen; Fischer, Hubertus; Stocker, Thomas F.; Muglia, Juan; Ferreira, David; Marcott, Shaun A.; Brook, Edward; Buizert, Christo
• 署名单位: Oregon State University; University of Bern; University of Bern; National Physical Laboratory - UK; University of New South Wales Sydney; University of Kiel; University of St Andrews; Centro Nacional Patagonico (CENPAT); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); University of Reading; University of Wisconsin System; University of Wisconsin Madison
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13267
• DOI: 10.1073/pnas.2319652121
• 发表日期: 2024-05-21
• 关键词: north-atlantic climate; deep ice core; overturning circulation; wd2014 chronology; carbon isotopes; scale changes; records; variability; storage; release

摘要

The last glacial period was punctuated by cold intervals in the North Atlantic region that culminated in extensive iceberg discharge events. These cold intervals, known as Heinrich Stadials, are associated with abrupt climate shifts worldwide. Here, we present CO 2 measurements from the West Antarctic Ice Sheet Divide ice core across Heinrich Stadials 2 to 5 at decadal - scale resolution. Our results reveal multi - decadal - scale jumps in atmospheric CO 2 concentrations within each Heinrich Stadial. The largest magnitude of change (14.0 +/- 0.8 ppm within 55 +/- 10 y) occurred during Heinrich Stadial 4. Abrupt rises in atmospheric CO 2 are concurrent with jumps in atmospheric CH 4 and abrupt changes in the water isotopologs in multiple Antarctic ice cores, the latter of which suggest rapid warming of both Antarctica and Southern Ocean vapor source regions. The synchroneity of these rapid shifts points to wind - driven upwelling of relatively warm, carbon - rich waters in the Southern Ocean, likely linked to a poleward intensification of the Southern Hemisphere westerly winds. Using an isotope - enabled atmospheric circulation model, we show that observed changes in Antarctic water isotopologs can be explained by abrupt and widespread Southern Ocean warming. Our work presents evidence for a multi - decadal - to century - scale response of the Southern Ocean to changes in atmospheric circulation, demonstrating the potential for dynamic changes in Southern Ocean biogeochemistry and circulation on human timescales. Furthermore, it suggests that anthropogenic CO 2 uptake in the Southern Ocean may weaken with poleward strengthening westerlies today and into the future. Significance Earth's climate system and carbon cycle interact in myriad ways that can add or remove CO 2 from the atmosphere. We use Antarctic ice cores to resolve four multi- decadal- scale CO 2 rises of up to 14 ppm that occurred during the most recent glacial period. These abrupt rises coincide with cold periods and iceberg discharge in the North Atlantic. Ice cores show synchronous abrupt warming in Antarctica and vapor source regions, which is consistent with increasing Southern Ocean ventilation due to shifting Southern Hemisphere westerly winds. Our results highlight past periods of dynamic changes in Southern Ocean biogeochemistry and circulation that occurred on human timescales and suggest that Southern Ocean CO 2 uptake may weaken as Southern Hemisphere westerlies strengthen in the future.