Understanding and simulating the magnitude and timing of the rise in atmospheric carbon dioxide levels at the end of the last ice age has been a major challenge for the Earth Science research community. At the same time, a well-informed long-term societal response to climate changes requires a detailed understanding of climate-carbon cycle feedbacks on a variety of timescales. This project addresses these challenges through an in-depth study of the evolution of the marine carbon cycle over the past 25,000 years and its relation to ocean circulation changes and carbon reservoir exchanges. The information gained from this project will be beneficial for assessing the performance of earth system models under past, present and future climate conditions.
Using a series of transient earth system model experiments with time-varying boundary conditions, the research team will identify deglacial ocean circulation scenarios that reproduce the existing paleoceanographic tracers, with special focus on radiocarbon. By including other age tracers into the proposed model simulations, the fidelity of various radiocarbon-based "ventilation" age methods, such as the projection age and the benthic-planktonic age difference method will be tested. The proposed numerical experiments will provide deeper physical insights into the dynamics of climate-carbon cycle feedbacks. Specific questions that will be addressed include:
1. How did the time-varying signal of atmospheric radiocarbon production rates "propagate" into the deep ocean? 2. How did ocean circulation changes during the last glacial termination affect the three-dimensional structure of radiocarbon anomalies in the world's oceans? 3. What is the potential carbon storage capacity of the Arctic Ocean under glacial periods? 4. What is the spatial and temporal variability of reservoir ages over the course of Termination 1 and into the Holocene?
