近日，美国亚利桑那大学Thirumalai, Kaustubh和科罗拉多大学DiNezio, Pedro N.团队合作取得一项新成果。他们的最新研究提出，未来极端厄尔尼诺现象的增加由过去的冰川变化支持。相关论文于2024年9月25日发表在《自然》杂志上。

据悉，厄尔尼诺现象，即厄尔尼诺—南方涛动(ENSO)现象的温暖阶段放大了全球气候变率。不确定的气候模式预测限制了人们评估这些气候事件，在人为温室效应变暖下是否会变得更加极端的能力。古气候记录提供了对过去变化的估计，但尚不清楚它们是否能约束未来预测的潜在机制。

本研究使用一种数值模拟的机制，该机制根据过去和未来营力一致的变化，允许模型验证古气候数据，模拟机制与观测到的极端厄尔尼诺现象的动力学一致。由于洋流和风的强烈耦合，西太平洋暖池水迅速向东扩张，从而形成了这种现象。这些耦合相互作用在冰川条件下减弱，因为更强的沃克环流驱动了更深的混合层。

由此导致的ENSO变异性的减少和极端厄尔尼诺现象的出现，得到了一系列热带太平洋古海洋学记录的支持，这些记录显示，在ENSO敏感关键海洋区域，包括赤道中部太平洋的新数据，冰川温度变化减少。模拟数据对过去变率的一致性，以及跨气候状态的一致机制，支持了较浅的混合层和较弱的沃克环流，驱动更频繁的极端厄尔尼诺现象的预测。

附：英文原文

Title: Future increase in extreme El Nino supported by past glacial changes

Author: Thirumalai, Kaustubh, DiNezio, Pedro N., Partin, Judson W., Liu, Dunyu, Costa, Kassandra, Jacobel, Allison

Issue&Volume: 2024-09-25

Abstract: El Nino events, the warm phase of the El Nino–Southern Oscillation (ENSO) phenomenon, amplify climate variability throughout the world. Uncertain climate model predictions limit our ability to assess whether these climatic events could become more extreme under anthropogenic greenhouse warming. Palaeoclimate records provide estimates of past changes, but it is unclear if they can constrain mechanisms underlying future predictions. Here we uncover a mechanism using numerical simulations that drives consistent changes in response to past and future forcings, allowing model validation against palaeoclimate data. The simulated mechanism is consistent with the dynamics of observed extreme El Nino events, which develop when western Pacific warm pool waters expand rapidly eastwards because of strongly coupled ocean currents and winds. These coupled interactions weaken under glacial conditions because of a deeper mixed layer driven by a stronger Walker circulation. The resulting decrease in ENSO variability and extreme El Nino occurrence is supported by a series of tropical Pacific palaeoceanographic records showing reduced glacial temperature variability within key ENSO-sensitive oceanic regions, including new data from the central equatorial Pacific. The model–data agreement on past variability, together with the consistent mechanism across climatic states, supports the prediction of a shallower mixed layer and weaker Walker circulation driving more frequent extreme El Nino genesis under greenhouse warming.

DOI: 10.1038/s41586-024-07984-y

Source: https://www.nature.com/articles/s41586-024-07984-y