Mismatch of glacier extent and summer insolation in Southern Hemisphere mid-latitudes
Mismatch of glacier extent and summer insolation in Southern Hemisphere mid-latitudes
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DOI：
10.1130/g36477.1
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发表时间：
2015-05-01
期刊：
影响因子：
5.8
通讯作者：
Schwartz, Roseanne
中科院分区：
文献类型：
--
作者：
Doughty, Alice M.;Schaefer, Joerg M.;Schwartz, Roseanne
在这里，我们解决了一个长期存在的冰河时代气候之谜，称为“米兰科维奇理论的美中不足”。“利用地貌测绘和Be-10表面暴露测年，我们发现新西兰南阿尔卑斯山普卡基冰川在上一个冰河时代的最大期形成了五个冰碛带。它们的年龄分别为41.76 ± 1.09 ka、35.50 ± 1.26 ka、27.17 ± 0.68 ka、20.27 ± 0.60 ka和18.29 ± 0.49 ka。这五个最大值跨越了整个岁差周期的夏季日照强度在南阿尔卑斯山的纬度。在南美洲中纬度地区的智利湖区，夏季日照和冰川范围之间也存在类似的不匹配。因此，与米兰科维奇将北方冰盖与北纬65度的夏季日照联系起来形成鲜明对比的是，南部中纬度冰川的行为与当地夏季日照强度无关。相反，冰川范围之间的41.76万年和18.29万年，以及在最后终止，与南大洋表面温度和大气中的二氧化碳。
Here we address a long-standing puzzle of ice-age climate called the "fly in the ointment of the Milankovitch theory." Using geomorphic mapping and Be-10 surface-exposure dating, we show that five moraine belts were formed during maxima of the last ice age by the Pukaki glacier in New Zealand's Southern Alps. They afford ages of 41.76 +/- 1.09 ka, 35.50 +/- 1.26 ka, 27.17 +/- 0.68 ka, 20.27 +/- 0.60 ka, and 18.29 +/- 0.49 ka. These five maxima spanned an entire precessional cycle in summer insolation intensity at the latitude of the Southern Alps. A similar mismatch between summer insolation and glacier extent also characterized the Chilean Lake District in the mid-latitudes of South America. Thus, in apparent contrast to northern ice sheets linked by Milankovitch to summer insolation at 65 degrees N latitude, the behavior of southern mid-latitude glaciers was not tied to local summer insolation intensity. Instead, glacier extent between 41.76 ka and 18.29 ka, as well as during the last termination, was aligned with Southern Ocean surface temperature and with atmospheric carbon dioxide.