Collaborative Research: Resolving the LGM ventilation age conundrum: New radiocarbon records from high sedimentation rate sites in the deep western Pacific

Oregon State University, Corvallis OR

Investigators

Abstract

During ice ages the ice sheets expand from the polar regions into the middle latitudes. Using samples of air trapped in Antarctic ice, scientists have determined that atmospheric carbon dioxide levels were 30% lower during the last ice age. This project tests whether the circulation of the deep ocean slowed down enough during the last ice age to allow carbon dioxide to build up in the deep ocean. Radiocarbon techniques will be used to date how long deep waters resided in the deep Pacific before returning the surface. The results are important for understanding how the oceans and the atmosphere interact during ice ages. This project will provide training for undergraduate and graduate students, and students will have an opportunity to participate in the research cruise to collect the samples. This project will acquire new high-resolution stable isotope and radiocarbon data from high deposition rate sites in the western North Pacific. Filling the deep Pacific data gap is essential to assess the hypothesis that a more sluggish ocean circulation allowed respired carbon to accumulate in the abyssal Pacific, leading to lower atmospheric carbon dioxide levels during the Last Glacial Maximum. The research will address one of the grand challenges in paleoclimate science: What controls atmospheric carbon dioxide levels on glacial/interglacial timescales? The new samples are critical because previous attempts to evaluate whether ventilation ages were greater during glaciations has been hampered by a lack of high-resolution data sets from the deep Pacific, which is the largest potential reservoir for the storage of metabolically- derived carbon. The project will support the training of students from three institutions who will participate in the research cruise and collaborate in the lab. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.