The response of Earth’s climate system to different perturbations and forcings can be studied using data from the geologic past. I am interested in how carbon storage in the ocean has varied in quantity and in character, both as a response to and as a driver of changing climate. Geochemical proxies that reflect characteristics of past oceanic conditions can be measured in marine sediments to reconstruct how oceans have changed biologically, chemically, and physically through time.
I am working on both the validation and application of these geochemical proxies for paleoceanography. On the validation side, I’ve been determining off-axis 230Th and metal fluxes along ridge crests, and whether 231Pa/230Th ratios reflect segment-integrated hydrothermal scavenging in sediments near mid-ocean ridges (Lund, Pavia et al. 2019). I have also collaborated on several projects examining the proxy systematics of sediment flux tracers (Middleton et al. 2020, Costa et al. 2020), redox tracers (Jacobel et al. 2020), and dust flux tracers (Jacobel et al. 2019). Ongoing work is examining the use of combined sediment flux tracers (230Th, 3He, 10Be) to date metalliferous sediment deposits, and the utility of sedimentary mercury fluxes as potential tracers of organic matter flux in the Southern Ocean.
On the application side, I am studying the mechanisms and changes in ventilation of the Pacific sector of the Southern Ocean. Great quantities of respired CO2 were stored in the abyssal Pacific Ocean during the last ice age, but the mechanisms for this carbon storage are not yet clear. I am developing a record of sedimentary redox conditions and ventilation rate to constrain the role of changing physics in the Southern Ocean, where the bottom waters of the glacial Pacific were formed. Moving forward, I am interested in developing theories for past ocean circulation that are dynamically-plausible and physically-realistic.