Last glacial maximum/last deglacial South Pacific interannual to decadal climate variability - Sub-seasonal reconstructions from Tahiti reef corals
Final Report Abstract
Assessing the response of interannual climate variability in the tropical Pacific Ocean to future greenhouse warming is of paramount importance because of the dramatic global climate and socioeconomic impacts originating from this region. However, the dominant mode of Pacific atmosphere-ocean variability on interannual timescales, the El Niño- Southern Oscillation (ENSO), is poorly understood with respect to its behaviour under boundary conditions different from today. For last glacial conditions, proxy records of interannual climate variability in the Pacific are extremely rare, and limited to reconstructions of the hydrologic cycle. Here we present a monthly resolved reconstruction of sea surface temperature (SST) in the tropical South Pacific from 15,000 years ago at the end of the last glacial. This period was characterised by a substantial reduction in the strength of the Atlantic Meridional Overturning Circulation (AMOC) in response to massive iceberg discharge into the North Atlantic associated with Heinrich stadial 1 (HS1). Our Sr/Ca palaeotemperature record constructed from a fossil coral recovered by Integrated Ocean Drilling Program (IODP) Expedition 310 to Tahiti indicates pronounced interannual ENSO variability, even though the site is only weakly influenced by ENSO today. From our coral record and simulations with a comprehensive climate model we conclude that interannual ENSO variability in the tropical Pacific was strong during HS1. Our results imply that enhanced interannual variability in tropical Pacific SST is the response of ENSO to a reduced AMOC under glacial boundary conditions, a finding that can help to constrain climate models for more reliable climate change projections. Video published at Focus Online • http://www.focus.de/wissen/videos/klimaforschung/fossile-korallen-500-jahreklimageschichte-in-einem-meter-koralle_vid_10121.html
Publications
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(2007), IODP Expedition 310 reconstructs sea level, climatic, and environmental changes in the South Pacific during the last deglaciation, Scientific Drilling, 5, 4-12
Camoin, G.F., Iryu, Y., McInroy, D.B., IODP Expedition 310 Scientists including Felis, T.
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(2007), Proc. IODP, 310: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.)
Camoin, G.F., Iryu, Y., McInroy, D.B., Expedition 310 Scientists including Felis, T.
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(2009), Evidence for tropical South Pacific climate change during the Younger Dryas and the Bølling-Allerød from geochemical records of fossil Tahiti corals, Earth and Planetary Science Letters
Asami, R., Felis, T., Deschamps, P., Hanawa, K., Iryu, Y., Bard, E., Durand, N., Murayama, M.
