P2C2: High-resolution Reconstruction of the South American Monsoon History from Isotopic Proxies and Forward Modeling

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The South American summer monsoon (SASM) is of great socio-economic relevance to (sub)tropical South America, delivering water for ecosystem integrity and human activities including agriculture, sanitation, hydropower production and many other socioeconomic purposes. Year-to-year variations in monsoon strength, onset and demise dates have been linked to drought and floods and can cause widespread economic damage. Yet little is known about how the SASM has varied in the past and how it responds to changes in natural (volcanic or solar) and man-made (aerosols and greenhouse gases) perturbations. In this project, a scientist from the State University of New York at Albany and his collaborators will reconstruct the SASM history for the past 1000 years using ice core data from the Quelccaya ice cap in the Peruvian Andes to learn more about the envelope of natural monsoon variability. The Quelccaya site was chosen because almost all snowfall is associated with the SASM (~85%), it contains a long, high-resolution and precisely-dated ice-core record, and has been the focus of long-term on-site climatologic and glaciologic monitoring and calibration programs. Using these on-site data sets, combined with isotope-enabled model simulations for the past millennium, the scientists will develop a so-called forward model that allows reconstructing monsoon variations upstream over the Amazon basin since the year 850 AD. Given the growing concerns over future changes in monsoon characteristics due to enhanced greenhouse gas concentrations, a better understanding of natural monsoon variability and its sensitivity to external forcing is absolutely essential. The project's progress will be documented on the Quelccaya blog website. The project also includes additional educational aspects such as training of a graduate student and a Postdoctoral Research Associate, and integrating methods and results developed in this project into undergraduate and graduate classrooms.