The last ice age was characterized by dramatic climate oscillations that appear to be linked to changes in the oceans meridional overturning circulation (MOC). Direct evidence for changes in the rate of MOC remains limited because traditional tracers can only provide snapshots of past water mass configurations without information about property transport. In this project, a new dynamical tracer of water circulation, Pa/Th, will be used to produce high-resolution, continuous 60,000-year record of MOC in the Atlantic Ocean during marine isotope stage 3. This research will be conducted on two high-quality cores from the subtropical and subpolar North Atlantic Ocean and will be carried out in parallel with complementary sedimentological and geochemical analyses as well as modeling studies. These data will explore linkages and phasing within the ocean-climate system and provide theoretical constraints on the interpretation of Pa/Th as a circulation proxy. This project will involve students in their research and in teaching at MIT/WHOI, and through NSF-funded and voluntary efforts to provide undergraduates with research experience in their studies. The PIs will continue outreach through presentations at college campuses and discussions in media such as newspapers and radio broadcasts. All data will be archived and made available to the scientific community as well as to the general public through web-based access at WHOI and NGDC.
