HOLIVAR2006 Abstracts
Palaeoclimate reconstructions from the Antarctic Peninsula: diatoms as indicators of environmental change.
Anna Hey1, Jennifer Pike1, Claire Allen2 and Dominic Hodgson2
1School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park Place, Cardiff. CF10 3YE, UK
2British Antarctic Survey, High Cross, Madingley Road, Cambridge. CB3 0ET, UK
Contact: Anna Hey (heyar@cardiff.ac.uk)
During the 20th century, the Antarctic Peninsula has exhibited the most rapid changes in temperature in the Southern Hemisphere. Atmospheric temperatures have risen by nearly 3°C in the past 50 years (Turner et al. 2005), which is more than double that of the global warming rate. A key question facing scientists and policy makers is whether this warming is part of the natural variability in the climate system or are anthropogenic activities upsetting the balance in this delicate climate system. When looking to the future, it is crucial to understand the periodicity, amplitude, and rate of climate changes in the past.
The main aim of this research project is to address questions on natural variability in the Earth's system through the Holocene, specifically links between the ocean and terrestrial environments. It is widely accepted that temperatures globally through the Holocene were probably relatively stable and far less variable than the glacial-interglacial transition. However, 'flickers' do exist in proxy records for the Holocene period, documenting several optima and minima. The driving force of climate change on these shorter time scales is believed to lie in the oceans (Broecker 1997). This project focuses on the Southern Ocean and aims to reconstruct changes in water mass circulation on the continental shelves of the Antarctic Peninsula, fluctuations in sea-ice extent and ice shelf collapse events, both spatially and temporally.
Preliminary results of detailed fossil diatom assemblage analysis of marine cores from several locations along the Antarctic Peninsula will be presented. Diatoms are unicellular, eukaryotic, photosynthetic micro-organisms that secrete a siliceous cell wall. In the marine realm, they are extremely common in high latitudes, particularly the Southern Ocean. Their use as proxies is based on the response of species to limiting factors, tracking changes in surface water mass characteristics and sea-ice extent. Future work will involve the augmentation and integration of the marine dataset with data retrieved from lake sediments and ice cores from the Antarctic Peninsula, to propose links between the terrestrial and marine environments. Through comparison, it is hoped that the timing of events will be discerned, thus allowing forcing mechanisms to be assigned to the observed climatic change.
Broecker, W. S., 1997. Thermohaline Circulation, the Achilles Heel of Our Climate System: Will Man-Made CO2 Upset the Current Balance? Science 278, 1582-1588.
Turner, J., Colwell, S. R. et al., 2005. Antarctic Climate Change During the Last 50 Years. International Journal of Climatology 25, 279-294.
Anna is a first year research student. Her studentship is funded by the Natural Environment Research Council (NERC), with the British Antarctic Survey (BAS) as a CASE partner. The title of her research project is "Palaeoclimate reconstructions from the Antarctic Peninsula: linking lake and marine records". To achieve this, detailed marine fossil diatom assemblage and marine sedimentary biomarker records will be compared with new terrestrial and ice core data recovered as part of the BAS core programme CACHE – PEP (Climate and chemistry, specifically the natural climate variability component project – extending the Americas Pole-Equator-Pole palaeoclimate transect through the Antarctic Peninsula to the South Pole).