ACE · Antarctic Canyon Experiment (ACE): How do Ice sheets affect turbidity currents and organic carbon cycling?

Turbidity currents, akin to underwater avalanches, are rapid, destructive, sediment-rich bodies of water that flow down-slope. They destroy seafloor infrastructure and transport and store organic carbon (OC), impacting climate over long (>1,000 yr) timescales. Global climate is controlled by atmospheric carbon dioxide, so understanding the processes influencing OC transfer and burial between Earth’s major stores is crucial to predict and mitigate against future climate change. Currently turbidity currents are largely excluded from global carbon models, mainly due to challenges in measuring these processes directly, with no turbidity currents measured yet at high latitudes. Antarctica disproportionately affects climate regulation, storing 40% of all anthropogenic carbon in the ocean, with projected climatic changes likely to affect future storage. I propose an innovative Antarctic Canyon Experiment (ACE) to directly measure Antarctic turbidity currents and OC for the first time. ACE involves novel deployments of subsea acoustic and optical instruments over 12-months, seafloor sampling and high-resolution seafloor mapping using Autonomous Underwater Vehicles, to establish the causes, character, and behaviour of Antarctic turbidity currents and OC. I will determine how turbidity currents and OC changed under past climates using extensive palaeoclimate, sedimentary and geochemical data and advance ocean-sediment-carbon models to predict how turbidity currents and OC will change under projected future scenarios. The outputs will drive forward global carbon models and climate mitigation policies by providing the first parameterisations of these processes, enabling improved representation of processes influencing the global carbon cycle. The outputs represent a paradigm shift in quantifying the role of high-latitude turbidity currents in OC cycling by assessing past, present and future impacts of climate on Antarctic turbidity currents and OC transfer to the deep ocean.