Monthly Tahiti coral Sr/Ca and oxygen isotope data from IODP Hole 310-M0024A

The early last glacial termination was characterized by intense North Atlantic cooling and weak overturning circulation. This interval between ~18,000 and 14,600 years ago, known as Heinrich Stadial 1, was accompanied by a disruption of global climate and has been suggested as a key factor for the termination. However, the response of interannual climate variability in the tropical Pacific (El Niño-Southern Oscillation) to Heinrich Stadial 1 is poorly understood. Here we use Sr/Ca in a fossil Tahiti coral to reconstruct tropical South Pacific sea surface temperature around 15,000 years ago at monthly resolution. Unlike today, interannual South Pacific sea surface temperature variability at typical El Niño-Southern Oscillation periods was pronounced at Tahiti. Our results indicate that the El Niño-Southern Oscillation was active during Heinrich Stadial 1, consistent with climate model simulations of enhanced El Niño-Southern Oscillation variability at that time. Furthermore, a greater El Niño-Southern Oscillation influence in the South Pacific during Heinrich Stadial 1 is suggested, resulting from a southward expansion or shift of El Niño-Southern Oscillation sea surface temperature anomalies.

末次冰消期早期以北大西洋剧烈降温与翻转环流减弱为典型特征。这一发生于约18000至14600年前的时段被称为海因里希冷期1（Heinrich Stadial 1），彼时全球气候发生扰动，且被认为是末次冰消过程的关键驱动因素之一。然而，热带太平洋年际气候变率（厄尔尼诺-南方涛动，El Niño-Southern Oscillation）对海因里希冷期1的响应机制仍不甚明晰。本文利用塔希提（Tahiti）化石珊瑚中的锶钙比（Sr/Ca），以月分辨率重建了约15000年前的热带南太平洋海表温度。与现代不同，彼时塔希提海域在典型厄尔尼诺-南方涛动周期下的南太平洋海表温度年际变率十分显著。本研究结果表明，厄尔尼诺-南方涛动在海因里希冷期1期间仍处于活跃状态，这与当时该现象变率增强的气候模型模拟结果一致。此外，研究还提出海因里希冷期1期间厄尔尼诺-南方涛动对南太平洋的影响更强，这一现象源于厄尔尼诺-南方涛动海表温度异常区的南扩或位移。