Bremerhaven, 2 November 2012. Dr Juliane Müller will be awarded a second place in the German Study Prize on 6 November in Berlin. The Körber Foundation honours the geoscientist from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association for her pioneering PhD thesis on sea ice distribution. The results of her research will facilitate fundamental improvements in climate forecasting.
The Körber Foundation awards the German Study Prize to young scientists conducting research into current and socially relevant subjects. Three first prizes and six second prizes are awarded annually under the patronage of the Federal President to researchers of all disciplines who have completed outstanding PhDs. With a total value in excess of EUR 100,000, the Study Prize is one of the mostly highly endowed for young scientists in Germany.
Juliane Müller receives the award for her PhD thesis in which she demonstrates how the sea ice distribution has altered in the Arctic. Thanks to her findings, the sea ice conditions of the past 30,000 years can be regionally reconstructed. The geoscientist thus aims at the weak point of many climate models. “The existing climate models frequently encountered difficulties in realistically reflecting changes in sea ice coverage. They also usually have no data from the past so that, for example, the melting of the ice over the last decade has been greatly underestimated,” explains Juliane Müller. However, it is important to make the right estimates because the retreat of the sea ice affects not only the Arctic ecosystem but in the long term alters the ocean currents and air circulations which also influence the European weather system. The imprecision of the models therefore makes it difficult for scientists to predict how the current ice melts will impact the climate. These are gaps which Juliane Müller would like to close through her research.
The geoscientist used biomarkers in her experiments for the PhD thesis to determine the sea ice distribution of the past. Scientists can interpret a biomarker, also referred to as fossil molecule, like the fingerprint of dead organisms. When algae die, for example, their remains sink to the sea bed where they deposit in layers during the course of the years. These deposits are referred to as sediments. Researchers can analyse the biomarkers of a living organism in sediment samples and determine by means of the layering when a specific type of algae proliferated.
In 2007 researchers at Plymouth University were already using a diatom biomarker to draw conclusions about the sea ice distribution. The diatom grows exclusively in sea ice. Scientists therefore assumed that the diatom biomarkers would indicate whether and when an area was covered by sea ice. However, if the biomarker was absent this could mean two things. Either the area was ice-free, or the sea ice was extraordinarily thick because if the ice mass is too compact no light will penetrate and the diatom algae cannot grow.
This ambiguity was the reason for Juliane Müller to extend the biomarker research approach. “I decided to use a second biomarker instead of concentrating only on the diatom. The marine phytoplankton proved to be suitable for this purpose. It preferably grows in ice-free water and reacts very sensitively to light deficiency. This enabled me to set up three assumptions: if the biomarkers of both the diatom and the phytoplankton were absent, the sea ice was very thick at the given time. If the fossil molecule of the diatom was absent but that of the phytoplankton evident, the area must have been ice free. By contrast, if I only found the biomarker of the diatom, I could inversely conclude that sea ice did exist but was not unusually thick.”
The long sediment cores and the surface sediments for her PhD thesis came from the Fram Strait, the name of the seaway between the North Atlantic and the Arctic Ocean. She first analysed the uppermost centimetres of the samples. “The surface sediments are like a snapshot of the environmental and climatic conditions of a certain region and map the most recent past. I examined the samples and then compared my results with the existing sea ice measurements from satellite recordings. Since my assumptions agreed with the actual values, I deduced that my method in the Fram Strait furnishes the correct results at least for younger sediments. I have now even been able to make quantitative statements about the extent of sea ice coverage in the past. This has encouraged me to test old sediment deposits for which there are no records on sea ice distribution,” explained Juliane Müller.
Since completing her PhD at the University of Bremen in October 2011, Juliane Müller has been working in the Research Unit Potsdam of the Alfred Wegener Institute where she is investigating whether the combination of the two biomarkers provides reliable data also beyond the confines of the Fram Strait. “I was delighted about my award. It confirms how important our research is and that it delivers results which are of relevance to society. My aim is therefore clearly to continue to improve on the climate models using sea ice reconstructions and so provide a foundation for reliable climate predictions.”
Notes for Editors:
Biographical information on Dr Juliane Müller
Juliane Müller (30) studied Applied Geosciences at the Technical University of Berlin from 2001-2007. Following this she moved to the Marine Geology and Paleontology Section of the Alfred Wegener Institute in Bremerhaven as scientific assistant, and took a PhD course in geosciences at the University of Bremen. She successfully completed her PhD in October 2011. The original title of her PhD thesis is ”Last Glacial to Holocene variability in the sea ice distribution in the Fram Strait/Arctic Gateway – A novel biomarker approach“. She has worked at the Alfred Wegener Institute since, conducting postdoctoral research into the reconstruction of historical climate processes.
Juliane Müller is at your disposal for any questions you may have: phone +49 (0)331 288-2208; e-mail: juliane.mueller(at)awi.de
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The Alfred Wegener Institute conducts research in the Arctic and Antarctic and in the high and mid-latitude oceans. The Institute coordinates German polar research and provides important infrastructure such as the research icebreaker Polarstern and stations in the Arctic and Antarctic to the international scientific world. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.