P2C2: Western Pacific Warm Pool Hydroclimate during the Last Glacial Maximum and the Deglaciation

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The West Pacific Warm Pool (WPWP) plays an important role in the global hydrological cycle, and its variability has significant socioeconomic consequences around the world. Understanding past climate conditions can improve predictions of future climate changes in this key region and beyond. This study will extend both the spatial and temporal resolution of paleoclimate data for the WPWP by studying cave formations (stalagmites) for two key periods: the Last Glacial Maximum (LGM; 19,000-21,000 years ago), when the mean climate was much colder than today, and the deglaciation (11,000-19,000 years ago), during which the global climate went through abrupt changes. Comparison between the cave data from a network of sites and model outputs will strengthen the climate interpretations made, and will improve the fidelity of both the reconstructions and the climate models. This study will generate time series of stalagmite d18O, an established proxy for rainfall amount in the tropics, from the Philippines (eastern, central, and western sites), the Solomon Islands, and Vanuatu. These sites cover a wide range of precipitation variability, as seen during the modern era, and will provide information about past climate variability at sites that currently have little to no data. This study will sample the full range of the WPWP hydrologic response to climate change by reconstructing rainfall from the LGM to the Holocene. The end members of the cold LGM and the warm Holocene provide a measure of how sensitive WPWP rainfall is to global mean temperature. The temporal evolution during the deglaciation reveals the magnitude and spatial pattern of WPWP rainfall changes associated with abrupt climate events, and how much of a role the tropics participate in these events. The proxy data will be compared with various climate model simulations from the CMIP5 and PMIP2/PMIP3 archives and other sources, focusing on the spatial pattern and seasonality of climate changes, as well as the commonalities and diversity of different models. To investigate the teleconnection mechanisms of past abrupt climate changes, additional experiments will also be conducted with an atmospheric model. The proxy-model comparison will help validate climate models, which are being used for future climate projections, and the detailed model analysis and additional experiments will elucidate the mechanism of past abrupt climate changes. The research team will work closely with local scientists in the developing countries of Vanuatu and the Philippines, exchanging knowledge about climate issues and water availability, issues that have societal and security implications for small island nations. The project will provide a research experience an undergraduate student recruited through the GEOFORCE program, which is a selective outreach program of the Jackson School of Geosciences that trains high school students, mainly from demographic underrepresented in the geosciences, and involves them in fieldwork.