Paula J. Reimer
Senior Lecturer in Palaeoecology
Director of the Centre for Climate, the Environment & Chronology (14CHRONO)
Telephone (UK): 028 9097 3980
Telephone (International): +44 28 9097 3980
Room Number: Palaeoecology G5
Ph.D. Geological Sciences, University of Washington, 1998
(Dissertation: Carbon cycle variations in a Pacific Northwest lake from the late glacial to early Holocene)
M.S. Biophysics, Iowa State University, 1976
B.S. Physics, Iowa State University, 1974
Chronology: 14C measurement, calibration, regional offsets and marine and freshwater reservoir corrections
Palaeoclimate: Effect of past climate change on the ocean- atmosphere-biosphere system
Carbon cycle: origin, diagenesis and residence time of organic carbon compounds in sediments, soils, and peats
My research interests are focused on carbon in both modern and palaeoenvironments as a tracer of geochemical processes, as key component in climate variability, and especially as a chronological tool. The 14CHRONO AMS facility is in its early stages of development, so the focus is now on 14C measurements, quality control and sample pretreatment processes.
Underlying both palaeoclimate and archaeological studies is the need for robust high-resolution chronologies so that comparisons between climate records can be made and the timing of events determined. Radiocarbon dating is one of the primary chronological tools for the Quaternary but must be calibrated with measurements of known age material. I have been involved with radiocarbon calibration since 1986 and now lead the IntCal working group. The IntCal group published the latest internationally ratified radiocarbon calibration datasets 26 ka BP (terrestrial and marine) in 2004. Beyond 26 ka BP available calibration datasets had large discrepancies at that time but new measurements on corals, foraminifera, speleothems, and floating tree-ring chronologies and the statistical framework developed for IntCal04 should make it possible to construct a calibration dataset for this time period.
Carbon accumulation in peat and soil is an important carbon reservoir but is poorly represented in climate models. I am working with collaborators at Lawrence Livermore National Laboratory, the University of California and USGS on a field study of the role of dissolved organic carbon (DOC) in soil carbon sequestration. We are using 14C, 13C-NMR, and stable isotopes of soil density fractions, DOC, and microbial biomass to determine pathways and exchange rates. This project will result in more accurate and comprehensive soil carbon cycling models at the site level, which will in turn improve the accuracy of global carbon cycling models. A Marie Curie fellowship project starting in 2007 will investigate High Arctic wetland sensitivity to climate variation using palaeoenvironmental tools. Past hydrological change and carbon accumulation patterns will be investigated explicitly at two time scales - the recent past of the last 200 - 300 years and total Holocene history (the last 12,000 years). Results of this research will provide new information for understudied Arctic ecosystems and underutilised palaeoenvironmental records that will be useful to climatologists, hydrologists, wetland biologists, and the general Arctic system science community.
In addition, I oversee the development of the radiocarbon calibration programs CALIB and CALIBomb and a database of marine carbon reservoir corrections at www.calib.org. My goal is to document regional differences and changes in the ocean mixed layer carbon reservoir over time in many locations, both to improve radiocarbon calibration for marine samples and as a record of ocean circulation changes.