Synchronous retreat of Thwaites and Pine Island glaciers in response to external forcings in the presatellite era

• 成果类型: Article
• 署名作者: Clark, Rachel W.; Wellner, Julia S.; Hillenbrand, Claus- Dieter; Totten, Rebecca L.; Smith, James A.; Miller, Lauren E.; Larter, Robert D.; Hogan, Kelly A.; Graham, Alastair G. C.; Nitsche, Frank O.; Lehrmann, Asmara A.; Lepp, Allison P.; Kirkham, James D.; Fitzgerald, Victoria T.; Barrera, Georgina Garcia-; Ehrmann, Werner; Wacker, Lukas
• 署名单位: University of Houston System; University of Houston; UK Research & Innovation (UKRI); Natural Environment Research Council (NERC); NERC British Antarctic Survey; University of Alabama System; University of Alabama Tuscaloosa; University of Virginia; State University System of Florida; University of South Florida; Columbia University; University of Cambridge; Leipzig University; Swiss Federal Institutes of Technology Domain; ETH Zurich
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9347
• DOI: 10.1073/pnas.2211711120
• 发表日期: 2024-03-12
• 关键词: amundsen sea embayment; antarctic ice-sheet; grounding-line retreat; circumpolar deep-water; west antarctica; shelf; bay; FLOW; bathymetry; widespread

摘要

Today, relatively warm Circumpolar Deep Water is melting Thwaites Glacier at the base of its ice shelf and at the grounding zone, contributing to significant ice retreat. Accelerating ice loss has been observed since the 1970s; however, it is unclear when this phase of significant melting initiated. We analyzed the marine sedimentary record to reconstruct Thwaites Glacier's history from the early Holocene to present. Marine geophysical surveys were carried out along the floating ice-shelf margin to identify core locations from various geomorphic settings. We use sedimentological data and physical properties to define sedimentary facies at seven core sites. Glaciomarine sediment deposits reveal that the grounded ice in the Amundsen Sea Embayment had already retreated to within similar to 45 km of the modern grounding zone prior to ca. 9,400 y ago. Sediments deposited within the past 100+ y record abrupt changes in environmental conditions. On seafloor highs, these shifts document ice-shelf thinning initiating at least as early as the 1940s. Sediments recovered from deep basins reflect a transition from ice proximal to slightly more distal conditions, suggesting ongoing grounding-zone retreat since the 1950s. The timing of ice-shelf unpinning from the seafloor for Thwaites Glacier coincides with similar records from neighboring Pine Island Glacier. Our work provides robust new evidence that glacier retreat in the Amundsen Sea was initiated in the mid-twentieth century, likely associated with climate variability.