Tropical Pacific temperature seasonality around Meltwater Pulse-1A from IODP Expedition 310 corals
Final Report Abstract
The overall aim of this project was to provide insights into the evolution of seasonality in tropical Pacific sea surface temperature during the last deglaciation, using modern and fossil (IODP Expedition 310 – ‘Tahiti Sea Level’) corals from Tahiti (French Polynesia). First, successful multi-colony Sr/Ca-temperature proxy calibration for Tahiti modern corals recovered from the vicinity of the Expedition 310 drill sites accomplished in this project will be useful for future paleoclimate reconstructions from corals throughout French Polynesia and the entire Pacific Ocean. Second, Sr/Ca analysis of last deglacial Tahiti fossil corals from IODP Expedition 310 showed that the last deglacial seasonal temperature amplitude at the sea surface was lower compared to today. Latter suggests that the temperature annual cycle at Tahiti during the last deglaciation mainly follows the seasonal insolation cycle that again is controlled by changes in Earth’s orbit around the sun. It can be concluded that these orbital variations have the most noticeable effect on Tahiti temperature seasonality during the last deglaciation rather than local effects. For instance, the Meltwater Pulse-1A apparently did not affect temperature seasonality at Tahiti. An exception to this overall pattern is observed for the Younger Dryas cold period of the Northern Hemipshere, where an elevated temperature seasonality was reconstructed at Tahiti, which was comparable to today, and which is accompanied by anomalies in the hydrological cycle. Third, absolute reconstructions of coral Sr/Ca-based sea surface temperature suggest an influence of Northern Hemisphere climate events, such as the Younger Dryas cooling or Bølling/Allerød warm period on central tropical South Pacific climate, likely through atmospheric teleconnections. Fourth, seasonal cycles in skeletal δ13C are best explained through variations in linear extension rates, as coral growth appeared to be reduced during the last deglacial and early Holocene compared to today. Latter is likely as a result of less favourable thermal conditions at that times. However, we note anomalously high linear extension rates in our oldest corals from Heinrich Stadial 1, just prior to the onset of Meltwater Pulse-1A.
Publications
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Last Deglacial Environmental Change in the Tropical South Pacific From Tahiti Corals. Paleoceanography and Paleoclimatology, 39(2).
Knebel, Oliver; Felis, Thomas; Asami, Ryuji; Deschamps, Pierre; Kölling, Martin & Scholz, Denis
