Personnel at IGV
Pearce, Christof
Post-doctoral researcher
Email: christof.pearce[at]geo.su.se
Phone: +46 (0) 8 16 47 49, +46 (0) 73 521 08 46
Room: R216
About Me

My research deals with the reconstruction of past changes in ocean conditions based on analysis of marine sediment records from the North Atlantic and Arctic Ocean. The purpose of my work is to improve our understanding of natural variability of ocean circulation patterns and sea surface conditions such as temperature and sea ice cover. For this I study samples from marine sediment cores using a multi-proxy approach including sedimentological, geochemical, and micropaleontological methods. My main expertise lies with the analysis of fossil diatoms, unicellular algae that lie at the base of the marine food web. These primary producers in the phytoplankton have siliceous cell walls that may preserve in ocean floor sediments and can therefore be used to reconstruct sea surface conditions of the past. The postdoctoral research I am conducting at Stockholm University consists of two separate projects.

Labrador Sea paleoceanography
This research project deals with past oceanic variability in the Labrador Sea during the last deglaciation and early Holocene epoch. From this very recent geological past, several periods are known during which disruptions in the Atlantic Meridional Overturning Circulation have triggered episodes of rapid climatic change in the Northern Hemisphere, e.g. the 8.2 kyr event and the Younger Dryas. The origins of these periods of reduced overturning of the ocean circulation are still widely debated, though probably caused by massive release of fresh water from the remains of the North American ice sheet. The main goal of this project is to study the mechanisms driving changes in ocean circulation in the Labrador Sea, with particular focus on periods during which ocean circulation strength in the North Atlantic is believed to have been disrupted. I am currently working on the analysis of sediment cores from northern Newfoundland and West Greenland.

Arctic Ocean sea ice variability
The other project that I am working on concerns past variability of sea ice in the Arctic Ocean. Arctic sea ice plays a critical role in the Earth’s climate system because of the positive ice-albedo feedback mechanisms as well as its control on ocean-atmospheric heat exchange and potential influence on the thermohaline circulation. As a result of its amplified response to recent global warming, Arctic sea ice has declined sharply over the last decades, which is often interpreted as one of the most visible examples of anthropogenic climate change. Key to improving our understanding of Arctic sea ice cover and its reaction to external forcing is the reconstruction of past variability through paleo-records. For this purpose I will be among others working with samples obtained through the 2014 SWERUS-C3 Expedition in the Arctic Ocean. I will apply sedimentological analyses (grain size distribution and X-ray diffraction analysis) accompanied by high resolution diatom analysis and measurements of the sea ice biomarker IP25.
My current work is funded by an Individual Postdoctoral Research Grant from the Danish Council for Independent Research – Natural Sciences (FNU grant no. 4002-00098B) as well as by the Knut and Alice Wallenberg Foundation.
Research website at Aarhus University: http://person.au.dk/en/christof.pearce@geo

Diatom  At work on ship.

 

 

Department of Geological Sciences
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