The Southern Ocean's role in determining atmospheric CO2 levels: new insights from novel biogenic silica records of seawater pH

Two new tools will be developed for determining ocean pH based on the isotopic and elemental composition of boron in siliceous marine sponges and diatoms. These will be applied to sponge and diatom fossils preserved in deep-sea cores in the Southern Ocean to reconstruct past changes in seawater acidity and dissolved CO2 content, and evaluate the critical changes in nutrients and marine productivity that control the release or uptake (sequestration) of CO2 from the atmosphere. This research will lead to a better understanding of the future role of the oceans in sequestering fossil fuel emissions and the resulting impact that increasing acidification of the oceans will have on marine ecosystems.