Title: The radiocarbon clock needs a makeover: integrating pantropical tree species into the atmospheric post-AD1950 14C global map to better track carbon cycle

Abstract: Radiocarbon (14C) dating allows us to better understand the human past and the carbon cycle. The technique’s success relies on very precise measurements of 14C activity in carbonaceous materials. As 14C ages do not represent exact calendar years, independently radiocarbon-dated materials exhibiting annual layers are necessary to correlate 14C ages to the proper timing of events. First, I will give a brief overview of the state of the atmospheric 14C reconstructions based on tree ring measurements, the lessons learned from the advent of nuclear weapons tests in the early 20th century, and the effects of atmospheric circulation affecting 14C distributions around the globe. Second, I will discuss how to extend the observational record by developing annually resolved atmospheric post-AD 1950 14C data using cellulose material from rigorous dendrochronologically-dated tree rings across the Intertropical Convergence Zone (ITCZ). I will show how tree species can be reliably pre-screened through replication of the “bomb-peak” by tree ring/14C measurements of selected calendar years surrounding the 14C bomb pulse and by quality control measurements of reference materials. Finally, I will show a newly produced 14C record from a moisture-sensitive tree-ring chronology at the edge of the Equator in the eastern Amazon Basin, the first of its kind. This record is part of a project granted by NSF to complement and update the global post-AD1950 14C curves. Developed tree-ring 14C records would be modelled in order to spatially and temporally expand the global atmospheric 14CO2 distribution map present available, the CALIB 14C (CALIBomb), managed by the International Calibration (IntCal) group.

Speaker Information
Name: 
Guaciara dos Santos
Title: 
Project Scientist
Department: 
Earth System Science
Affiliation: 
UC Irvine
Date and Time: 
Tuesday, October 15, 2019 - 3:30pm
Location: 
The Jenkins Room | Croul Hall 3101