Oceans and Global Change

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Oceans and Global Change The ocean initiates, amplifies and mediates global climate change on time-scales ranging from less than a year to thousands of years. Understanding the ocean’s past variability is thus of paramount importance for climate science. Indeed, paleo-records are the only observational constraints we have on climate timescales. Paleoceanography aims to reconstruct past ocean conditions and dynamics through analysis of proxies or tracers, measurable descriptors of environmental parameters, which are preserved in the sedimentary record, especially in the deep ocean where sedimentation has been continuous for long periods. The overarching objective of my research is to describe, understand, and quantify the distribution of sedimentary particles and of tracers, such as specific biomarkers or isotopes; to establish their mechanistic relation to processes of interest, such as ocean currents, surface ocean conditions, or marine biogeochemical cycles; and to determine their variability through time, with a specific focus on the last glacial-interglacial cycle. Specific long-term questions that guide my research and address critical gaps in our understanding are: To what extent did the marine nitrogen cycle cause the glacial-interglacial swings in atmospheric CO2 concentrations? How did the tropical Pacific influence global climate change in the past? How can we better quantify past sea surface temperatures and salinities? It is becoming increasingly evident and accepted by expert scientists that understanding past ocean and climate variability is key to understanding the present-day ocean/climate system and for modelling potential future global climate change during the “Anthropocene”. My research program - in international collaboration with other research groups - will continue to contribute critical constraints on rates and amplitudes of past ocean and climate change.