Dr. Stewart Fallon

B.A., M.S., PhD
Senior Research Fellow

I trained as a marine scientist at the University of San Diego (B.A. and M.S. Marine Science) and The Australian National University, obtaining a PhD in isotope geochemistry in 2001. I then went to the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory to learn radiocarbon preparation and measurements using AMS. In 2004 I moved to the Chemistry, Biology and Nuclear Science Division at LLNL and developed isotopic measurements and maps using the CAMECA nanoSIMS. In 2006 I returned to Australia to take up a research Fellow position as the head of the newly refurbished Radiocarbon Dating Laboratory at the Research School of Earth Sciences, The Australian National University. Since 2010 I have been a Fellow at the Research School of Earth Sciences. My research interests include radiocarbon dating, using radiocarbon as a tracer for the carbon cycle, developing proxy records of marine environment using trace element and isotopic records from biogenic archives and examining past environmental change to help understand our future climate.


2010 – present –  Senior Fellow and Head of the Radiocarbon Dating Laboratory, Research School of Earth Sciences, The Australian National University

2007-2010 –  Research Fellow and Head of the Radiocarbon Dating Laboratory, Research School of Earth Sciences, The Australian National University

2004-2006 – Environmental Chemist, Chemical Biology and Nuclear Science

Division, Lawrence Livermore National Laboratory

2001-2004 - Postdoctoral Researcher, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory

Research interests

  • Isotope Geochemistry
  • Physical Oceanography
  • Environmental Chemistry (Incl. Atmospheric Chemistry)
  • Geochronology
  • Climate Change Processes
  • Palaeoclimatology
  • Synchrotrons; Accelerators; Instruments And Techniques
  • Forensic Biology
  • Chemical Oceanography
  • Oceanography
  • Ecological Applications

Examining Ocean Acidification in a natural coral reef setting, Milne Bay, PNG

Rising atmospheric carbon dioxide (CO2) affects marine ecosystems not only by altering the global climate such as increasing sea surface temperatures, storm intensity and rainfall variability, but also by changing the chemistry of seawater, a process called ‘ocean acidification’ (OA; Raven et al. 2005). There is reliable observational time series documenting that seawater carbonate chemistry (partial pressure of dissolved inorganic carbon including CO2, pH and alkalinity) is changing rapidly due to uptake of anthropogenic CO2 from the atmosphere. Current CO2 concentrations (393 ppm) already exceed pre-industrial levels (~280 ppm) by 40%, reducing global mean oceanic pH by  ~0.1 units. This rate of change is ~100-times faster than what occurred during the last >2 Mio years (Hönisch et al. 2009).  It is predicted that CO2 will continue to rise, without drastic global mitigation strategies, possibly to up to 1000 ppm by year 2100 (IPCC 2007: Solomon et al. 2007).

Porites coral cores have been collected along a pH gradient from unique volcanic CO2 seeps in Milne Bay Province, Papua New
Guinea. The CO2 gas bubbles emerging from the reefs provide local ocean acidification conditions similar to those
predicted for the middle to the end of this century, and beyond. Volcanic CO2 bubbling through the seawater
in Milne Bay is free of radiocarbon, resulting a unique signal that is preserved in the coral skeleton. We have
measured the radiocarbon content of the coral skeleton back through time from sites heavily impacted by CO2
and ”control” sites not impacted by CO 2 seeps. Three impacted sites show an increase of CO2 into the DIC by
4%, 10% and 14% (Figure 1).

Figure 1. This figure shows the amount of 14C in the CO2 impacted vs. control sites in PNG. The impacted sites have 4, 10, 14% addition of CO2, this corresponds to a significant decrease in pH at the impacted sites.


Convenor EMSC3019 Coral Reef Field Course

EMSC3023 Marine Biogeochemistry