Details of Award
NERC Reference : NE/C517117/1
The North Atlantic Ice-Climate System: Reconstructing the Provenance and Phasing of Ice Rafting Events using Palaeointensity Assisted Chronologies.
Grant Award
- Principal Investigator:
- Professor W Austin, University of St Andrews, School of Geography and Geosciences
- Co-Investigator:
- Professor RM Ellam, Scottish Universities Env Research Cen, SUERC
- Grant held at:
- University of St Andrews, School of Geography and Geosciences
- Science Area:
- Marine
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Global Change
- Science Topics:
- Quaternary Science
- Glacial & Cryospheric Systems
- Palaeoenvironments
- Climate & Climate Change
- Abstract:
- Research into past climate change has shown that the Earth experienced rapid and recurring climate shifts during which temperatures in the North Atlantic region changed by up to l0?C in a matter of decades. Evidence for this comes from natural archives in the form of ice cores and marine sediment cores whose properties record past air temperatures, atmospheric composition and precipitation (from ice cores) and past ocean temperatures, ocean salinity, nutrients and global ice volume (from marine cores). So what were the causes of these events and if such extreme climate change occurred in the past, could it be a feature of future climate? It is thought to be the strength of the global thermohaline circulation controlled by the balance of heat ('thermo) and salt ('haline'), that controls North Atlantic temperatures. At present, a strong, north-flowing 'Gulf Stream' carries equatorial heat to high latitudes, warming the NE Atlantic. However sustenance of this warm current depends on its return flow as high-salinity deep ocean water. Any change in the formation of this deep water can therefore seriously affect both North Atlantic temperatures and the entire global ocean circulation system. Global warming, a matter of both political and scientific debate, is particularly relevant in this context because the consequential melting of Northern Hemisphere glacial ice is likely to reduce the salinity of water at the site of deep water formation, weakening the influence of the warm Gulf Stream. Thus, the ice, ocean and climate systems are intrinsically linked and subtle changes in one system can trigger extreme responses in the others. It is therefore important to understand the mechanisms which link these systems to work out the ultimate causes behind past climate change in order to predict future climate change. What is still unknown is the precise timing of these events as the errors associated with their ages are actually greater than the interval between them. An exciting new way of dating marine cores is being developed using changes in the Earth's magnetic field overtime. Specific minerals in marine sediments record the same magnetic changes, independent of their location; so different cores can be matched up and dated using their magnetic properties. Such a timescale (a Palaeointensity Assisted Chronology; PAC) could be the key to piecing together climate records over time. This study aims to reconstruct one element of the ice-ocean-climate system in the North Atlantic over the last glacial period. The study will focus on a marine core taken from an area known to record high-frequency ice-rafting events where the Northern Hemisphere ice sheets have seemingly responded to climate change by delivering large volumes of icebergs into the North Atlantic Ocean. These events appear in marine cores as intervals with high concentrations of coarse-grained sediment, whose chemical properties and geology reflect the landmass from which they were eroded by glacial ice. Therefore by studying these properties and dating the events, the exact timing of ice-rafting from different ice sheets can be calculated. This is important in studying how ice sheets built up and decayed and this can then be related to records of ocean temperature and salinity from the same core to place the ice sheet dynamics into an oceanographic and climatic context. The core will be taken as part of a specific expedition of the integrated Ocean Drilling Program: an international research cruise collecting cores to construct a North Atlantic PAC for records of ice-ocean-climate interactions on millennial timescales. The new PAC will mean that the reconstructed ice-rafting events can be accurately dated and correlated with records from other cores. This will build up a picture of events not only over time by examining the record within one core but across the North Atlantic region at specific times by matching the same events between cores using the PAC.
- NERC Reference:
- NE/C517117/1
- Grant Stage:
- Completed
- Scheme:
- Directed Pre FEC
- Grant Status:
- Closed
- Programme:
- IODP
This grant award has a total value of £1,743
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Other Costs |
|---|---|
| £205 | £1,538 |
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