Climate controlled sedimentation in Maxwell Bay, King George Island, Antarctica


Contact
gerhard.kuhn [ at ] awi.de

Abstract

Climatic change in Antarctica is strongest over the Antarctic Peninsula where in places the annual mean temperatures increased by 0.5 K per decade through the past 60 years. The impact of this warming trend is clearly visible in the form of retreating glaciers and melting ice sheets, loss of sea ice and strong meltwater discharge into the coastal zone. While it is generally accepted that the rapidity of the present climate change bears a significant anthropogenic aspect, it is not clear whether the effects caused by the warming trend are exceptional and unprecedented or whether the reaction of the environment is similar to that of earlier climate phases such as the Medieval Warm Period (MWP) about 1,000 years ago. One of the major goals of the joint international research project IMCOAST is to investigate the strength of the recent warming trend and its impact on the marine environment of the West Antarctic Peninsula (WAP). The study we present here reveals the Upper Holocene climatic history based on high-resolution sediment cores from Maxwell Bay (King George Island, WAP) and information on the actual processes triggered or altered by the recent warming trend based on sedimentologic and hydroacoustic investigations in Potter Cove, a tributary fjord to Maxwell Bay. Long sediment cores from Maxwell Bay reveal grain-size changes that can be linked to cold and warm phases such as the Little Ice Age (LIA) and the MWP. Generally, warm phases are finer grained than cold phases as a result of longer and stronger melting processes during the warm phases. It is suggested that meltwater plumes carry fine-grained sediment out of the surrounding fjords into Maxwell Bay where it settles in suitable areas to produce sediments that have a modal value around 16 µm. This mode is largely absent in sediments deposited during e.g. the LIA. However, post LIA sediments are depleted in the 16 µm-mode sediment suggesting slightly different conditions during the last century. One reason might be that the recent warming trend is mainly characterized by winter and spring warming rather than by summer warming. Sediment distribution in Potter Cove reveals only a small sheltered patch of this very fine sediment. From the front of the glacier that retreated onto land during the past decades slightly coarser sediment is spreading out in the fjord. Data of an acoustic ground discrimination system together with sidescan-sonar data and some underwater-video ground truthing allows to identify and discriminate morphologic, sedimentologic and also habitat units that elucidate the presently active environmental processes.



Item Type
Conference (Poster)
Authors
Divisions
Programs
Peer revision
Peer-reviewed
Publication Status
Published
Event Details
American Geophysical Union Fall Meeting, 03 Dec 2012 - 07 Dec 2012, San Francisco.
Eprint ID
32135
Cite as
Hass, H. C. , Kuhn, G. , Wittenberg, N. , Wölfl, A. C. and Betzler, C. (2012): Climate controlled sedimentation in Maxwell Bay, King George Island, Antarctica , American Geophysical Union Fall Meeting, San Francisco, 3 December 2012 - 7 December 2012 .


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