P2C2: New Zealand Climate in Three Warm Periods

The flux of carbon dioxide from the atmosphere to the Southern Ocean is largely controlled by the position of the westerly winds in the Southern Hemisphere. In the present climate system, when these winds shift southwards, the carbon sink in the Southern Ocean is diminished and this has implications for the rate at which carbon dioxide accumulates in the atmosphere. This project aims to provide a perspective from past climate states that will help understand the future of such processes linking climate, atmosphere and ocean circulation and carbon dioxide accumulation. The project will also help to understand how bioavailable dust influences ocean circulation and cycling of carbon in the Southern Ocean, which has implications for the global carbon cycle. The researchers will address these goals by establishing reconstructions of the climate and environment from peatland sediments on the South Island of New Zealand with a focus on three warm periods during Earth's most recent climate history. The project will also provide opportunities for international collaboration for students and secondary school educators by participation in the Experiences for Earth Science Teachers Program (ESTEP). Secondary school teachers from New York and New Zealand will be paired to participate in the research and develop their experiences into curricula and supplemental films to engage their students in science.

Specifically, the research project will establish a series of reconstructions of climate and environmental change from peatland sediments on the South Island of New Zealand during two historical warm periods, the early- to mid-Holocene and Marine Isotope Stage 5e (MIS-5e) and compare them with trends associated with current warming. The researchers will compare these with the preceding glacial periods (MIS-2, -4, and -6). This project provides the funds to establish a chronology for cores obtained from well positioned peatlands on New Zealand's South Island at study sites that are either within the modern westerly wind field or near its northern edge. The researchers will use organic geochemical and stable isotope proxy methods to reconstruct Southern Hemisphere westerly winds during these warm periods represented in the chronologies of the cores. These data will be coupled to ongoing measurements of modern water isotopes and meteorological observations and GCM simulations to directly interpret stable isotope measurements from sediments as records of westerly wind variability.

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.