Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA.
Science. 2014 Apr 4;344(6179):84-7. doi: 10.1126/science.1246172.
The appearance of permanent El Niño-like conditions prior to 3 million years ago is founded on sea-surface temperature (SST) reconstructions that show invariant Pacific warm pool temperatures and negligible equatorial zonal temperature gradients. However, only a few SST records are available, and these are potentially compromised by changes in seawater chemistry, diagenesis, and calibration limitations. For this study, we establish new biomarker-SST records and show that the Pacific warm pool was ~4°C warmer 12 million years ago. Both the warm pool and cold tongue slowly cooled toward modern conditions while maintaining a zonal temperature gradient of ~3°C in the late Miocene, which increased during the Plio-Pleistocene. Our results contrast with previous temperature reconstructions that support the supposition of a permanent El Niño-like state.
300 万年前以前永久性厄尔尼诺现象的出现是基于表明太平洋暖池温度不变和赤道纬向温度梯度可忽略不计的海面温度（SST）重建。然而，可用的 SST 记录很少，这些记录可能受到海水化学变化、成岩作用和校准限制的影响。在这项研究中，我们建立了新的生物标志物-SST 记录，并表明 1200 万年前太平洋暖池的温度高了约 4°C。暖池和冷舌都在向现代条件缓慢冷却，而在中新世晚期保持了约 3°C 的纬向温度梯度，在更新世-全新世期间有所增加。我们的结果与之前支持永久性厄尔尼诺现象状态假设的温度重建结果形成对比。
