NOAA/WDS Paleoclimatology - West Australia Coral Sr/Ca Data and SST Reconstructions for the last 200 Years

Increasing intensity of marine heat waves has caused widespread mass coral bleaching events, threatening the integrity and functional diversity of coral reefs.  Here, we demonstrate the role of inter-ocean coupling in amplifying thermal stress on reefs in the poorly studied southeast Indian Ocean (SEIO), through a robust 215 year (1795-2010) geochemical coral proxy sea surface temperature (SST) record. We show that marine heat waves affecting the SEIO are linked to the behaviour of the Western Pacific Warm Pool on decadal to centennial timescales, and are most pronounced when an anomalously strong zonal SST gradient between the western and central Pacific co-occurs with strong La Niña's. This SST gradient forces large-scale changes in heat flux that exacerbate SEIO heatwaves. Better understanding of the zonal SST gradient in the western Pacific is expected to improve projections of the frequency of extreme SEIO heatwaves and their ecological impacts on the important coral reef ecosystems off Western Australia.