Collaborative Research: Intertropical Convergence Zone Variations from Stable Oxygen Isotope Tree-ring Records in the Tropical Americas

This project specifically seeks to use stable oxygen isotopes (δ18O) measured in cellulose from the annual growth rings of trees located in Guatemala, Honduras, Ecuador, Peru, Bolivia and Chile to reconstruct wet season precipitation variability for at least the last 200 years across the neotropics to glean insights on large-scale tropical climate dynamics. The general goal of the research is to understand recent and potential future changes in the position and width of the Intertropical Convergence Zone (ITCZ) and how these changes may be tied to global modes of climate variability and could affect patterns of tropical rainfall in both the northern (NH) and southern (SH) hemispheres. The rational for the research strategy of using isotopes from tree cellulose is that the relative paucity of tree-ring records in tropical regions (a large geographic area and extensive ecosystem) prevents a more comprehensive understanding of the range of climate variability particularly at decadal to centennial time scales and in response to changes in radiative forcing. Such data are otherwise unavailable from modern observations, pilot studies, and paleoclimate data elsewhere in the world. The potential Broader Impacts include support for a postdoctoral researcher as well as graduate undergraduate students involved in the research and extensive interaction with international researchers. 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.