High latitude influence on ocean circulation during major climate events Supervisors: Professor Laura Robinson (Bristol), Dr Kate Hendry (Bristol), Dr David Barnes (British Antarctic Survey) The oceans are a critical component of the climate system – important for transporting heat across the equator, and for storing carbon and nutrients. Observations point towards changing rates of deep water production in recent decades, with potential impacts for global climate. Most of the deep waters filling the ocean basins forms in the high latitudes of the North Atlantic and Southern Oceans, so they are important locations for understanding this interaction. This project will use geochemical measurements in deep sea corals to examine high latitude ocean processes during some of the largest climate transitions in recent Earth history‐ the abrupt climate events of the last deglaciation, some 20,000 to 10,000 years ago. This PhD project will use the exciting new archive of deep sea corals to provide unique insights into the high latitude oceanic processes in the past. Unlike reef‐
forming corals found in shallow tropical areas, cold‐
water corals do not have algal symbionts so they are not restricted to the photic zone or to warm waters. As a result, they are found in all of the ocean basins, including the Southern Ocean and high latitude Northern regions, and at depths from a few metres to greater than 5,000m. The robust calcium carbonate skeletons of these corals are well preserved and can be dated using the decay of uranium to thorium. The chemistry of the growth layers within the coral skeletons reflects external environmental conditions and can preserve a record of rapid climate events in the ocean similar in temporal resolution to the atmospheric records preserved in ice cores. The anticipated results will have implications for understanding the global climate system. Specifically the project will fulfil two objectives: (a) use existing and novel geochemical analyses to reconstruct the history of ocean circulation over the last 50,000 years using deep‐sea coral skeletons. (b) use the combined data set to investigate the links between ocean circulation and global climate The project will use clean lab chemistry, mass spectrometry and interpretation of data in the context of existing paleoclimate records. The student is invited to participate in a major research cruise from Canada to Greenland using cutting edge technologies such as the Remotely Operated Vehicles (https://icylab.wordpress.com/). Further field work opportunities e.g. to the Southern Ocean may also be possible during the course of the PhD. Additional web resources and references: https://bristoloceans.wordpress.com/ https://www.bas.ac.uk/profile/dkab/#about Burke, A., Robinson, L.F., 2012. The Southern Ocean’s Role in Carbon Exchange during the Last Deglaciation. Science 335, 557‐561. Chen T. et al (2015) Synchronous Sub‐millennial Scale Abrupt Events in the Ocean and Atmosphere during the Last Deglaciation Science 349 (6255), 1537‐1541 Robinson, L.F, et al (2014) The geochemistry of deep sea coral skeletons: applications for palaeoceanography Deep Sea Research 99, 184‐198 Project Plan and Training It is anticipated that the project will begin with participation on a research cruise from Canada to Greenland in the Labrador Sea in 2017 (participation in this field program is encouraged but not required). The student will be based in Bristol, where the laboratory work will be carried out. During the course of the project the student will engage in research visits to BAS to discuss the results of the cruise, strategies for sampling coral material and to discuss and select samples from the BAS collections. Indeed, samples for the project are available through two sources (a) existing University of Bristol and British Antarctic Survey collections (b) Field programs during the PhD program. Additional research opportunities through BAS include research expeditions to Tristan da Cunha & St Helena and South Shetlands to Rothera in the Southern Ocean. As the project progresses these research visits will focus on interpretation of coral‐based records in the context of modern marine habitats. Regular group meetings will be held via skype. It is envisaged that the student will spend approximately 80% of their time at Bristol and 20% at BAS since the analytical work will be performed at Bristol, but this split of time is negotiable. This project has excellent training opportunities including geochemical laboratory skills, through to participation in field work, DTP training courses and external opportunities. Key training opportunities are described below, but additional training identified through discussion between the student and supervisors will be supplied where required. (A) Isotope Geochemistry in the Bristol Isotope Group: The student will be based in Bristol and become an integral member of the Bristol Isotope Group. Within this setting the student will receive one on one training in clean lab geochemistry, and undertake a bespoke mass spectrometry course at Bristol University. These skills will be honed under the guidance of Robinson, Hendry and other group members. The student will become an independent analytical isotope geochemist with special skills in uranium‐series geochemistry. (B) Radiocarbon analysis at BRAMS (Bristol Radiocarbon Accelerator Mass spectrometry) The student will be arriving at an exciting moment in Bristol with the recent opening of the new AMS facility for radiocarbon analysis. The student will have ample opportunity for hands on analysis in the facility allowing them to make an unprecedented set of 14C analyses as well as being at the cutting‐edge of AMS technology (C) Training in deep‐sea habitats and marine protected areas: Deep sea corals are indicator species for vulnerable marine ecosystems (VMEs). This project offers the opportunity to become involved in policy relevant science through co‐supervision of Dr Barnes and colleagues at BAS. The student will have receive unrivalled exposure to extensive collections of deep‐water coral samples and databases, suited to mapping out marine habitats, the use of deep sea corals as indicator systems, and the documentation and data needed to support the formation and continuation of Marine Protected Areas. (D) The student will have the opportunity to attend DTP and external climate modelling courses, allowing them to develop their quantitative skills throughout the course of the project. This training will provide the skill set required to take full advantage of the unique data sets generated during the project. (E) External courses will be encouraged where appropriate, including but not limited to the annual Urbino Summer School in Paleoclimatology.