[OCES Seminar] Tropical Pacific Rainfall Response to Glacial Meltwater Discharge 8-8.5 Kyr Ago Based on 2H/1H Ratios of Algal Lipids
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The Holocene is often described as having a warm, stable climate, a view supported by temperature reconstructions from polar ice and marine sediment cores. However, a wide variety of marine and continental climate reconstructions show substantial high- and low-frequency Holocene variations. The most well-known of these is the “8.2 kyr Event”, which occurred when a pulse of meltwater from glacial Lake Agassiz entered the NW Atlantic, disrupting the meridional overturning circulation (MOC) and cooling the North Atlantic region. Scant evidence detailing the degree to which this event influenced tropical hydroclimate exist. We reconstructed hydroclimate variations in the tropical Pacific Ocean from hydrogen isotope ratios (δ2H) of phytoplankton lipids from sediment cores collected in anoxic marine lakes on islands in Palau (7.5°N, 135°E) and the only permanent freshwater lake in the Galápagos (1°S, 89°W). Results of these analyses will be presented along with their implications for tropical Pacific hydroclimate changes during the 8.2 kyr event.
Julian (PhD, MIT; BS, MIT) is a marine organic chemist and climate scientist. His 130+ scientific publications in journals including Nature and Science have been cited >9,400 times. He’s been obsessed with weather and climate since childhood when his family evacuated in advance of a hurricane and a blizzard closed his school for a week. He and his lab develop paleoclimate records from sediment cores from throughout the world’s oceans and lakes. Molecular fossils and their hydrogen and carbon isotopic ratios are used to reconstruct past precipitation, temperature, and biological productivity. Reconstructing natural climate changes in the past provides the means to determine when the modern climate is outside the range of natural variability and improves predictions of how it will change in the future.