P2C2: Multi-Scale Analysis of Stable Isotope - Climate Relationships in Tropical Proxy Records

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This project takes advantage of recent advances in forward modeling of stable isotopic climate proxies. The researchers will combine modeling with new records of tropical Holocene climate variability from speleothems, lake records, and ice cores to better constrain the interpretation of terrestrial stable isotopic records of Oxygen and Deuterium at inter-annual to millennial timescales. Specifically, the researchers will evaluate the ability of the Goddard Institute for Space Studies (GISS) ModelE-R, an isotope-enabled ocean-atmosphere general circulation model, to reproduce Holocene climate variability in the tropics. The overall scientific aim of the research is to understand the influence of orbital forcing on the location of the Inter Tropical Convergence Zone (ITCZ), changes in the Hadley and Walker circulation cells, and the intensity of monsoons in each hemisphere and their respective influence on isotopes in model output and climate proxy data. The research has two specific research thrusts, as follows: 1) synthesize existing isotopic records into a spatio-temporal network that can be compared with GISS ModelE-R output at ~1,000 year time steps to obtain a dynamically consistent and physically plausible picture of changes in the tropical hydrological cycle throughout the entire Holocene; and 2) diagnose the climatic controls on isotopic variations in the model throughout the Holocene at various tropical proxy sites. The primary broader impacts involve support for a graduate student and assessing a climate model's ability to reproduce past variations in the tropical hydrologic cycle and its ramifications for future anthropogenic climate change projections.