NOAA/WDS Paleoclimatology - Houtman Abrolhos Island Sr/Ca, Oxygen Isotopes, SST and Sea-Level Reconstruction Data from 1795-2010

Variability of the Leeuwin current (LC) off Western Australia is a footprint of interannual and decadal climate variations in the tropical Indo-Pacific. La Niña events often result in a strengthened LC, high coastal sea levels and unusually warm sea surface temperatures (SSTs), termed Ningaloo Niño. The rarity of such extreme events and the response of the southeastern Indian Ocean to regional and remote climate forcing are poorly understood owing to the lack of long-term records. Here we use well-replicated coral SST records from within the path of the LC, together with a reconstruction of the El Niño-Southern Oscillation to hindcast historical SST and LC strength from 1795 to 2010. We show that interannual and decadal variations in SST and LC strength characterized the past 215 years and that the most extreme sea level and SST anomalies occurred post 1980. These recent events were unprecedented in severity and are likely aided by accelerated global ocean warming and sea-level rise.

西澳大利亚外海的李奥文海流（Leeuwin Current, LC）变率，是热带印度洋-太平洋年际与年代际气候变率的表征印记。拉尼娜事件通常会引发李奥文海流增强、沿岸海平面升高，以及异常偏暖的海表温度（SST），这类现象被命名为宁加洛尼诺事件。由于缺乏长期观测序列，这类极端事件的稀有性，以及东南印度洋对局地与远程气候强迫的响应机制，迄今仍未得到充分解析。本研究依托李奥文海流路径内复现性良好的珊瑚海表温度记录，结合厄尔尼诺-南方涛动（El Niño-Southern Oscillation）重建序列，对1795年至2010年的历史海表温度与李奥文海流强度开展了后报分析。结果表明，过去215年间海表温度与李奥文海流强度均存在显著的年际和年代际变率，且最极端的海平面与海表温度异常均出现于1980年之后。这些近年发生的极端事件在严重程度上均属史无前例，且很可能受到全球海洋加速变暖和海平面上升的助力。