My research is motivated by a desire to understand the interactions between ocean circulation, chemistry, and climate on a variety of timescales. To do this, I use isotope geochemistry and numerical modeling.  Current interests include:

Southern Ocean circulation and CO2
Overturning circulation in the Southern Ocean plays a key role in CO2 regulation and heat transport.  Changes in Southern Ocean circulation are thought to control glacial-interglacial CO2 cycles in the past, and may have an important influence on anthropogenic CO2 uptake in the future.  To understand these processes I use radiocarbon as a tracer of ocean-atmosphere CO2 exchange and ocean circulation.  Much of my work has focused on deep sea corals, which provide an excellent archive for radiocarbon and other geochemical tracers, and can be precisely dated using uranium and thorium isotope ratios (Burke and Robinson, 2012).  This geochemical work is coupled with circulation modelling, including the application of inverse methods to explore protactinium/thorium changes in the deep Atlantic (Burke et al., 2011), and new approaches to dynamical modelling of Southern Ocean circulation.

Sulfur biogeochemistry and climate forcing
The sulfur cycle exerts an important control on earth's surface redox state, is intertwined with a variety of biogeochemical reactions, and may act as a major climate forcer.  To gain insights into these processes I make measurements of sulfur isotope ratios, using a new multi-collector inductively-coupled-plasma mass spectrometry (MC-ICPMS) technique (Paris et al., 2013).  The key advantage of this method is that it allows us to make measurements on extremely small samples, opening up a variety of exciting new research possibilities.  Current work includes constraining riverine fluxes of sulfur to the ocean, and reconstructions of climate forcing from volcanic sulfate aerosols.