Onset of deglacial warming in West Antarctica driven by local orbital forcing
Onset of deglacial warming in West Antarctica driven by local orbital forcing
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DOI：
10.1038/nature12376
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发表时间：
2013-08-22
期刊：
影响因子：
64.8
通讯作者：
Wong, Gifford J.
中科院分区：
文献类型：
--
作者：
Fudge, T. J.;Steig, Eric J.;Wong, Gifford J.
最近一次冰川消融期间南半球变暖的原因仍然是一个有争议的问题(1，2)。关于北半球通过海洋热量再分配触发的假设，部分是基于南极东部冰芯突然开始变暖，可以追溯到18,000年前，这是北半球夏季高纬度太阳辐射强度从大约24,000年前的最低水平开始增加的几千年后(3，4)。另一种解释是，局部太阳辐射变化导致南半球独立变暖(2，5)。在这里，我们展示了来自南极洲西部的一项新的、每年一次的冰芯记录的结果，该记录协调了这两种观点。记录显示，18,000年前，西南极的积雪开始增加，同时二氧化碳浓度增加，东南极变暖，北半球变冷(6)，伴随着大西洋经向翻转环流的突然减少(7)。然而，南极洲西部的显著变暖至少在2000年前就开始了。环南极海冰的减少是由当地日照增加所驱动的，这可能是这种变暖的原因。受海洋影响的西南极记录表明，与东南极内陆冰芯所推断的相比，南大洋在冰川消融开始中发挥了更积极的作用，东南极内陆的冰芯在很大程度上与海冰变化隔绝。
The cause of warming in the Southern Hemisphere during the most recent deglaciation remains a matter of debate(1,2). Hypotheses for a Northern Hemisphere trigger, through oceanic redistributions of heat, are based in part on the abrupt onset of warming seen in East Antarctic ice cores and dated to 18,000 years ago, which is several thousand years after high-latitude Northern Hemisphere summer insolation intensity began increasing from its minimum, approximately 24,000 years ago(3,4). An alternative explanation is that local solar insolation changes cause the Southern Hemisphere to warm independently(2,5). Here we present results from a new, annually resolved ice-core record from West Antarctica that reconciles these two views. The records show that 18,000 years ago snow accumulation in West Antarctica began increasing, coincident with increasing carbon dioxide concentrations, warming in East Antarctica and cooling in the Northern Hemisphere(6) associated with an abrupt decrease in Atlantic meridional overturning circulation(7). However, significant warming in West Antarctica began at least 2,000 years earlier. Circum-Antarctic sea-ice decline, driven by increasing local insolation, is the likely cause of this warming. The marine-influenced West Antarctic records suggest a more active role for the Southern Ocean in the onset of deglaciation than is inferred from ice cores in the East Antarctic interior, which are largely isolated from sea-ice changes.