Increased frequency of extreme La Nina events under greenhouse warming
Increased frequency of extreme La Nina events under greenhouse warming
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DOI：
10.1038/nclimate2492
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发表时间：
2015-02-01
影响因子：
30.7
通讯作者：
Guilyardi, Eric
中科院分区：
文献类型：
--
作者：
Cai, Wenju;Wang, Guojian;Guilyardi, Eric
厄尔尼诺/南方涛动是地球年际气候变化的最主要来源，在厄尔尼诺和拉尼娜之间不规则地交替，并导致全球天气模式，生态系统，渔业和农业的破坏（1-5）。继1997-1998年极端厄尔尼诺事件之后的1998-1999年极端拉尼娜事件（6）在西太平洋国家将极端厄尔尼诺引起的严重干旱转变为毁灭性洪水，在美国西南部反之亦然（4，7）。在极端的拉尼娜事件期间，太平洋中部（8，9）的冷海面条件发展，从海洋大陆到太平洋中部产生了增强的温度梯度。最近的研究表明，厄尔尼诺特征在模拟未来温室效应时发生了强烈的变化（10-12），但拉尼娜将如何变化仍不清楚。在这里，我们从耦合模式相互比较项目第5阶段（参考文献13）进行的模拟中提出气候模拟证据，表明未来极端拉尼娜事件的频率几乎翻了一番，从每23年一次增加到每13年一次。这是因为预计海洋大陆的平均变暖速度比中太平洋更快，上层海洋垂直温度梯度增强，极端厄尔尼诺事件的频率增加，有利于极端拉尼娜事件的发展。大约75%的增长发生在极端厄尔尼诺事件之后的几年，因此预测从一年到下一年，相反的极端之间的波动更加频繁。
The El Nino/Southern Oscillation is Earth's most prominent source of interannual climate variability, alternating irregularly between El Nino and La Nina, and resulting in global disruption of weather patterns, ecosystems, fisheries and agriculture(1-5). The 1998-1999 extreme La Nina event that followed the 1997-1998 extreme El Nino event(6) switched extreme El Nino-induced severe droughts to devastating floods in western Pacific countries, and vice versa in the southwestern United States(4,7). During extreme La Nina events, cold sea surface conditions develop in the central Pacific(8,9), creating an enhanced temperature gradient from the Maritime continent to the central Pacific. Recent studies have revealed robust changes in El Nino characteristics in response to simulated future greenhouse warming(10-12), but how La Nina will change remains unclear. Here we present climate modelling evidence, from simulations conducted for the Coupled Model Intercomparison Project phase 5 (ref. 13), for a near doubling in the frequency of future extreme La Nina events, from one in every 23 years to one in every 13 years. This occurs because projected faster mean warming of the Maritime continent than the central Pacific, enhanced upper ocean vertical temperature gradients, and increased frequency of extreme El Nino events are conducive to development of the extreme La Nina events. Approximately 75% of the increase occurs in years following extreme El Nino events, thus projecting more frequent swings between opposite extremes from one year to the next.