Deglacial temperature history of West Antarctica
Deglacial temperature history of West Antarctica
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DOI：
10.1073/pnas.1609132113
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发表时间：
2016-12-13
影响因子：
11.1
通讯作者：
Severinghaus, Jeffrey P.
中科院分区：
文献类型：
--
作者：
Cuffey, Kurt M.;Clow, Gary D.;Severinghaus, Jeffrey P.
最近的冰期到间冰期的转变是一个了不起的自然实验，可以用来了解地球气候如何对各种强迫做出反应，包括大气中二氧化碳的增加。这种转变在极地冰盖中留下了直接的热残余，那里冰的特殊纯度和持续积累允许在其他环境中进行分析。对于南极洲，冰消期变暖以前仅受到冰芯中水同位素组成的限制，而没有对同位素对温度的敏感性进行绝对的测温评估。为了克服这一局限性，我们在一个深钻孔测量温度，并分析它们与冰芯数据重建西南极洲的表面温度的历史。冰消期升温为11.3 +/- 1.8摄氏度，约为全球平均值的两到三倍，与南极放大行星温度变化的理论预期一致。与南半球山脉冰川退缩的证据一致，南极变暖主要在15 kyBP完成，比北方半球早几千年。这些结果限制了冰消期间两半球之间海洋热传输的作用，并定量地限制了全球气候强迫对南极温度的直接影响。尽管气候模型在这方面的平均表现良好，但最近对冰消期气候历史的一些综合研究低估了南极变暖，敏感性最低的模型可能会被低估。
The most recent glacial to interglacial transition constitutes a remarkable natural experiment for learning how Earth's climate responds to various forcings, including a rise in atmospheric CO2. This transition has left a direct thermal remnant in the polar ice sheets, where the exceptional purity and continual accumulation of ice permit analyses not possible in other settings. For Antarctica, the deglacial warming has previously been constrained only by the water isotopic composition in ice cores, without an absolute thermometric assessment of the isotopes' sensitivity to temperature. To overcome this limitation, we measured temperatures in a deep borehole and analyzed them together with ice-core data to reconstruct the surface temperature history of West Antarctica. The deglacial warming was 11.3 +/- 1.8 degrees C, approximately two to three times the global average, in agreement with theoretical expectations for Antarctic amplification of planetary temperature changes. Consistent with evidence from glacier retreat in Southern Hemisphere mountain ranges, the Antarctic warming was mostly completed by 15 kyBP, several millennia earlier than in the Northern Hemisphere. These results constrain the role of variable oceanic heat transport between hemispheres during deglaciation and quantitatively bound the direct influence of global climate forcings on Antarctic temperature. Although climate models perform well on average in this context, some recent syntheses of deglacial climate history have underestimated Antarctic warming and the models with lowest sensitivity can be discounted.