Evolution of temperature and mobilization of terrigenous organic matter in the subarctic Northwest Pacific and adjacent Beringia since the Last Glacial Maximum

• Main Author: Meyer, Vera Dorothee
• Other Authors: Mollenhauer, Gesine, Diekmann, Bernhard
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2016
• Subjects: paleoclimate; Northwest Pacific; Beringia; Kamchatka; biomarker; sea surface temperature; mean air temperature; carbon cycle; permafrost; glaciation; last deglaciation; Last Glacial Maximum; 550; 550 Earth sciences and geology; ddc:550; Bering Sea; Pacific; Kamchatka Peninsula; North Atlantic; Subarctic; Siberia
• Online Access: https://media.suub.uni-bremen.de/handle/elib/1054; https://nbn-resolving.org/urn:nbn:de:gbv:46-00105274-15

In the subarctic Northwest Pacific and adjacent Siberia mean climate changes between the Last Glacial Maximum and the Holocene are poorly understood since climate records spanning the full LGM-Holocene transition are sparse. This thesis shall contribute to a better understanding of climate and environmental change since the LGM and the controlling mechanisms in the region by investigating the development of temperature, glaciation and export of terrigenous organic matter into the North Pacific (N Pacific). Biomarkers in sediment cores from the Western Bering Sea and the NW Pacific are applied as palaeoclimate archives. In the first part of the thesis LGM-to-Holocene sea surface temperature (SST) records for the marginal Northwest Pacific and the Western Bering Sea are established using the TEXL86 (Tetraether IndeX)-SST proxy. It is found that SSTs in both settings are determined by rapid atmospheric teleconnections with abrupt climate changes in the North Atlantic (N Atlantic) since 15 ka BP. Before 15 ka BP, only the Bering Sea was connected to N-Atlantic climate change. The NW Pacific remained disconnected from the N-Atlantic until 15 ka BP due to an oceanic linkage with the NE Pacific through the Alaskan Stream. The second part investigates the LGM-to-Holocene evolution of mean air temperature (MAT) of the Kamchatka Peninsula where climate archives do not reach beyond 12 ka BP. Using the CBT/MBT-palaeothermometry (Cyclisation of Branched Tetreathers and the Methylation of Branched Tetraethers indices) a continuous record in summer MAT is provided for the past 20 ka. It is found that glacial summers were as warm as at present. Likely, strong southerly winds, associated with a pronounced North Pacific High pressure system (NPH) over the subarctic NW Pacific, accounted for the warm conditions on Kamchatka. The deglacial temperature development was characterized by abrupt millennial-scale temperature oscillations during the past 15 ka BP. Considering that NE-Siberian glaciation is supposed to have been more ...