A Millennial Proxy Record of ENSO and Eastern Australian Rainfall from the Law Dome Ice Core, East Antarctica

ENSO causes climate extremes across and beyond the Pacific basin; however, evidence of ENSO at high southern latitudes is generally restricted to the South Pacific and West Antarctica. Here, the authors report astatisticallysignificantlinkbetweenENSOandseasaltdepositionduringsummerfromtheLawDome(LD) ice core in East Antarctica. ENSO-related atmospheric anomaliesfrom the central-western equatorialPacific (CWEP) propagate to the South Pacific and the circumpolar high latitudes. These anomalies modulate high- latitude zonal winds, with El Nino (La Nina) conditions causing reduced (enhanced) zonal wind speeds and subsequent reduced (enhanced) summer sea salt deposition at LD. Over the last 1010 yr, the LD summer sea salt(LDSSS)recordhasexhibitedtwobelow-average(ElNino-like)epochs,1000-1260 ADand1920-2009 AD, and a longer above-average (La Nina-like) epoch from 1260 to 1860 AD. Spectral analysis shows the below- average epochs are associated with enhanced ENSO-like variability around 2-5 yr, while the above-average epoch is associated more with variability around 6-7 yr. The LDSSS record is also significantly correlated with annual rainfall in eastern mainland Australia. While the correlation displays decadal-scale variability similar to changes in the interdecadal Pacific oscillation (IPO), the LDSSS record suggests rainfall in the modern instrumental era (1910-2009 AD) is below the long-term average. In addition, recent rainfall declines in some regions of eastern and southeastern Australia appear to be mirrored by a downward trend in the LDSSS record, suggesting current rainfall regimes are unusual though not unknown over the last millennium.