New ice core records from West Antarctica and their spatial context: from 1000 to 100,000 years

• Main Author: Rowell, Isobel
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Cambridge 2023
• Subjects: antarctic climate; antarctica; ice core; last 2k; last glacial period; last millennium; palaeoclimate; reconstruction; stable water isotope; Antarctic; West Antarctica; West Antarctic Ice Sheet; Ronne Ice Shelf; Sherman Island; Skytrain Ice Rise; Antarc*; Antarctica; EPICA; Ice Sheet; Ice Shelf; Pine Island
• Online Access: https://www.repository.cam.ac.uk/handle/1810/346978; https://doi.org/10.17863/CAM.94392

The West Antarctic Ice Sheet (WAIS) is vulnerable to warming as a result of anthropogenic climate change, with the potential to contribute several metres to global sea level rise over the coming centuries. The Thwaites and Pine Island glaciers are already undergoing acceleration due to climate change, threatening the stability of the WAIS. There is a need to understand the stability of the WAIS during warm periods, such as the Last Interglacial (LIG) when the WAIS is proposed to have retreated, and the Holocene prior to anthropogenic warming. Ice core records can be used to reconstruct climatic changes and infer past ice sheet configurations. However, existing long-term ice records are sparse. Two drilling campaigns were carried out under the WACSWAIN project, aiming to contribute two new ice records to refine the uncertainties of WAIS stability in warm periods. One drilled an ice core to bedrock (651m) on Skytrain Ice Rise, adjacent to the Ronne Ice Shelf; a second used a novel drilling technology (Rapid Access Isotope Drill, RAID), on Sherman Island (SI), obtaining ice chippings to a depth of 323 m. The RAID was previously deployed at Little Dome C in the East Antarctic, obtaining samples to 460 m depth. The records from RAID ice chippings and their continental spatial context are the focus of this thesis. Chemical and water isotope data from RAID-drilled ice samples are presented for the first time and are comparable to those of conventionally-drilled ice cores. The dataset from SI extends to over 1000 years before present, more than doubling the length of existing records from the coastal WAIS. SI shows little overall change in stable water isotope values over the last millennium, and does not demonstrate the increased accumulation rate in recent decades apparent in comparative cores. The RAID record of stable water isotopes from Little Dome C is compared with nearby EPICA Dome C to investigate the limits of common centennial scale variability. An Antarctic-wide array of water isotope records extending ...