final_program_abstracts[1]

11 IMSC Session Program
The use of chronologies in Holocene palaeoclimate
reconstruction
Monday - Parallel Session 3
Andrew C. Parnell and John Haslett
UCD and TCD, Dublin, Ireland
In estimating the timing of past environmental changes we always require a
chronology. That is, ages with associated uncertainty for a set of depth slices at which
a palaeoenvironmental indicator is found in a sediment core. Chronologies are used in
a variety of palaeoclimate sciences:
• In estimating the ages of past climatic events from pollen samples (eg Parnell
et al 2008)
• In reconstructing past Holocene climate (eg Haslett et al 2006)
• In creating records of past sea level change from foraminiferal-based transfer
functions (eg Horton et al 1999)
• In calculating oceanic offsets to the radiocarbon calibration curve.
The chronologies are created from uncertain dates taken from a much smaller sample
of slices, the number depending on factors such as availability of dateable material
and cost, amongst others. The statistical challenge is to combine the uncertain dates
with a suitable monotonic stochastic process which defines the chronological process.
Recently, a number of proposals for the nature of sedimentation changes over time
have been proposed in the statistical literature (eg Blaauw and Christen, 2005; Haslett
and Parnell, 2008) for radiocarbon-dated chronologies. The monotonic processes used
here are necessarily simple to balance the complexity of calibrating radiocarbon
determinations.
In this talk, I will discuss the stochastic processes behind chronology construction,
and how they may be enhanced with the further use of additional data and
sophisticated computational techniques.
Abstracts 71