Admissions > PhD by research > Research Projects > Climate variability in the North Atlantic in the last 20 kyrs

Climate variability in the North Atlantic

in the last 20 kyrs

Supervisors: Dr Daniela Schmidt, Dr Morten Andersen and Dr Joy Singarayer (School of Geographical Sciences)

Although the climate of the Holocene has sustained the growth and development of modern society, there is surprisingly little systematic knowledge about climate variability during this period. It has been shown over the last 10 years that the Holocene was significantly less stable than previously thought [1, 2]. A large number of higher resolution paleoclimate records spanning the last deglaciation, provide an unprecedented perspective on orbital and millennial-scale climate changes during this time period [6]. Understanding the drivers behind this natural variability underlying anthropogenic climate change, however, is the basis for predicting climate of the future [5]. While these exciting records provide great insights into the climate system, it is imperative to have a good geographic coverage to generate spatial response in critical areas.

One of the areas is the northern North Atlantic and the focus of this project. Newly collected material with a sedimentation rate of 1m/kyrs will allow us to study the climate variability of Holocene, including the 8.2 ka event and the Younger Dryas cold reversal with decadal variability. Data will be generated to detect changes in surface and deep water properties. Our understanding on climate variability and stability will be assessed by the analysis of related simulations of these time periods using a coupled ocean-atmosphere climate model, HadCM3.

The student will generate a robust age model in high sedimentation rate cores will be developed using 14C. Possible redistribution of sediments on the seafloor due to winnowing will be determined by measuring radioactive U-series daughter products in the sediment samples (230Th excess) at sites on the drift and to the east and west that have experienced different bottom water flow history (e.g. Henderson & Anderson, 2003). The results of this part of the study will indicate changes in deep water formation between the Labrador and Irminger Basins. This information will be corroborated with sortable silt analysis [4]. Surface water properties, such as temperature, salinity, productivity etc. will be analysed using isotopes and trace elements in planktic foraminifers [e.g.7, 2]. These will be combined with census counts to determine changes in the planktic foraminiferal fauna and determination of ice rafted debris to reconstruct the history of the Greenland ice sheet. The high temporal resolution data will provide improved knowledge concerning the natural variability, stability, and the relative timing of changes in the North Atlantic region during the Holocene and deglaciation. Similar analysis of the climate model, HadCM3, in terms of variability and phasing of related changes in the North Atlantic region will be performed to assess our understanding of natural Holocene variability as well as stability to freshwater perturbations. This will improve the predictability of threshold responses to future changes in freshwater balance in the North Atlantic.

Training

Training will be provided in state of the art geochemistry, climate modelling palaeoceanography, and micropalaeontology. In addition to preparing the student for a career in paleoclimate, it will provide additional transferable technical skills that would be of benefit within any future scientific or computationally-based career.

References

  1. Bond, G., et al. (1997). Science 278(5341): 1257-1266
  2. Carlson, A., et al. (2010) Geophysical research letters 36: L14704
  3. Chapman, M. R. and N. J. Shackleton (2000). Holocene 10(3): 287-291
  4. Hall, I. R., et al. (2004). Quaternary Science Reviews 23(14-15): 1529-1536
  5. Mayewski, P. A., et al. (2004). Quaternary Research 62(3): 243-255
  6. Shakun, J. D. and A. E. Carlson (2010). Quaternary Science Reviews 29(15-16): 1801-1816
  7. Thornalley, D. J. R., et al. (2009). Nature 457(7230): 711-714

Last updated: 20/10/11