Influence of North Mediterranean rainfall on triggering anoxia and sapropel deposition
About the Event:
There is increasing concern with anthropogenic greenhouse gas emissions that ocean warming in concert with summer and winter precipitation changes will induce anoxia in multiple ocean basins. In particular, the Intergovernmental Panel on Climate Change (IPCC) has identified the Mediterranean Sea as being susceptible to deoxygenation. The Mediterranean as a model miniature ocean is an ideal study area for the links between climate change and anoxia. In this talk, I will present reconstructions of past changes in ocean salinity and river runoff associated with rainfall variability that are linked with sapropel deposition – intervals of widespread anoxia in the Mediterranean during the current and past warm periods of the past two interglacials. Using the trace element and stable isotope composition of foraminifera, we find evidence that enhanced winter rainfall, during periods of precession minima and high seasonality across interglacials, was predominantly controlled by the respective eccentricity maxima. Such hydrologic changes in the western Mediterranean were possibly a contributing factor to basin-wide anoxia. These findings offer new insights into the cause and impact of winter rainfall changes in the Mediterranean during past warm periods, providing a paleo-perspective to ongoing discussions on the impact of climate change in the region.
About the Speaker:
Yama Dixit joined EOS earlier this year as a Research Fellow with Prof. Xianfeng Wang and Prof. Adam Switzer. Prior to joining EOS, she was a Marie Curie postdoctoral researcher at the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) in Brest, France. She completed her PhD from University of Cambridge, UK and has a Masters degree in Environmental Sciences from Jawaharlal Nehru University, New Delhi and BSc degree in Chemistry from Delhi University. Her research interests lies in understanding the patterns and mechanisms of past climate variability using chemistry of biogenic carbonates archived in ocean and lake sediments. Yama has worked on proxy reconstructions and paleoclimate dynamics, looking at the Asian and South American monsoon systems, changes in hydrology and effects on ancient societies, abrupt climate change, and most recently in France, the impact of changes in the westerlies on sapropel deposition.